Declining Sperm Count: Much More Than You Wanted To Know
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Is Sperm Count Declining?
People say it is.
Levine et al 2017 looks at 185 studies of 42935 men between 1973 and 2011, and concludes that average sperm count declined from 99 million sperm/ml at the beginning of the period to 47 million today.
Levine et al 2022 expands the previous analysis to 223 studies and 57,168 men, including research from the developing world. It finds about the same thing.
The “et al” includes Dr. Shanna Swan, a professor of public health who has taken the results public in the ominously-named Count Down: How Our Modern World Is Altering Male and Female Reproductive Development, Threatening Sperm Counts, and Imperiling the Future of the Human Race.
Is Declining Sperm Count Really "Imperiling The Future Of The Human Race”?
Swan’s point is that if sperm counts get too low, presumably it will be hard to have babies (though IVF should still work).
How long do we have?
This graph (source) shows pregnancy rate by sperm count per artificial insemination cycle. It seems to plateau around 30 million.
An average ejaculation is 3 ml, so total sperm count is 3x sperm/ml. Since sperm/ml has gone down from 99 million to 47 million, total count has gone down from ~300 million to ~150 million.
150 million is still much more than 30 million, but sperm count seems to have a wide distribution, so it’s possible that some of the bottom end of the distribution is being pushed over the line where it has fertility implications.
But Willy Chertman has a long analysis of fertility trends here, and concludes that there’s no sign of a biological decline. Either the sperm count distribution isn’t wide enough to push a substantial number of people below the 30 million bar, or something else is wrong with the theory.
Levine et al model the sperm decline as linear. If they’re right, we have about 10 - 20 more years before the median reaches the plateau’s edge where fertility decreases, and about 10 years after that before it reaches zero. Developing countries might have a little longer.
It feels wrong to me to model this linearly, although I can’t explain exactly why besides “it means sperm will reach precisely 0 in thirty years, which is surely false”. The authors don’t seem to be too attached to linearity, saying that “Adding a quadratic or cubic function of year to meta-regression model did not substantially change the association between year and SC or improve the model fit”.
Still, the 2022 meta-analysis found that the trend was, if anything, speeding up with time, so it doesn’t seem to be obviously sublinear.
How Long Has This Been Going On?
The first recorded claim about declining sperm counts was in Nelson & Bunge, 1974. They noticed that sperm counts seemed to be declining since the first good study in 1951. There were some previous small unreliable studies before 1951 (the earliest was 1929) that seemed to get vaguely similar numbers to the 1951 study. So, very speculatively, one might suggest that sperm counts started declining between 1951 and 1974.
See the next section for some problems with this story.
How Sure Are We That This Is Even Real?
Not too sure.
The authors of these studies are well-respected scientists - yes, even the one who wrote the book about imperiling the future of the human race - and they seem to be doing good statistics.
But an argument against might start with this graphic:
Each circle is an individual study examined in Levine’s first meta-analysis. I notice two things:
Yes, okay, that line is pointing very slightly down, and apparently this is statistically significant.
But also, the data are very noisy. Some studies from 2005 show higher sperm counts than most studies from the 1970s. The biggest pre-1980 study shows sperm counts very similar to today’s.
It looks like a lot depends on why these sperm count studies are so noisy, and how much we can trust their methodology. Here the best source is Auger et al, Spatiotemporal Trends In Human Semen Quality:
Human sperm production is widely believed to be declining over time, but evidence from the scientific literature is less clear. Studies based on repeated cross-sectional data from a single centre have shown mixed results. Among the numerous retrospective studies conducted in a single centre, only some included homogeneous groups of men and appropriate methods, and most of them suggest a temporal decrease in human sperm production in the geographical areas considered.
Conclusions reporting temporal trends in sperm production that came from existing retrospective multicentre studies based on individual semen data and those using means, medians or estimates of sperm production are questionable, owing to intrinsic limitations in the studies performed. Regardless of study design, studies on the percentage of motile or morphologically normal spermatozoa are still limited by the inherent variability in assessment.
Overall, available data do not enable us to conclude that human semen quality is deteriorating worldwide or in the Western world, but that a trend is observed in some specific areas.
Instead of comparing studies from all over the world, it might be safer to look at single-center studies, ie where a single hospital or lab has been recording sperm counts for decades, presumably using the same methods for the same population. The authors were able to find about seventy such studies. Unfortunately, they were pretty contradictory:
With respect to trends in sperm concentration (or total sperm count when concentration was not determined), 57% of studies reported a decrease in sperm production over time . . . 29% of all studies reported no change and 12% indicated an increasing trend.
Why such variable results? Here are some common confounders:
Where are sperm samples coming from? Some people give samples because they are sperm donors, others because they are infertile and want to figure out why. Infertile men may be infertile because they have unusually low-quality sperm. If something changes the fertile/infertile balance among sperm sample givers, or changes when people start worrying about fertility enough to give sperm samples, then data will be confounded. Especially the rise of IVF during the period under study has increased the degree to which infertile men might give sperm samples.
In the old days, when this was groundbreaking research, most studies were done in cutting-edge research centers in wealthy regions of advanced countries. These places tend to be healthier and have higher sperm counts. Now that this line of research has caught on, everyone is doing it, and that means more underdeveloped areas with worse health and lower sperm counts are in the dataset.
Sperm count is affected by age - if your area’s population is aging, that will change its average sperm count from year to year.
Different countries (and, in the US, different races) seem to have different sperm counts. If your community’s demographics are changing (eg immigration), that might change its average sperm count.
After ejaculation, sperm count decreases and takes a while to build back up again; if your community’s ejaculation frequency is changing (eg people have gained access to online porn), that will change its average sperm count.
But beyond all of this, collecting sperm is hard. Here’s Auger et al:
At the beginning of the 1980s, the WHO recommended standardized approaches for assessing human semen, which have evolved and been updated over time. However, some of the discussed studies began before the 1980s, when the WHO guidelines were implemented. In addition, many studies did not describe their methods precisely or did not follow the WHO guidelines at all. Furthermore, several studies stated that the WHO recommended procedures were followed, but the description of the procedures used suggests noticeable deviations from the recommended procedures.
Others even reported changing methods during the study period, for example, for sperm count analysis. Changing a procedure can be a notable confounding factor if the periods before and after the change are not analysed separately. For example, counting spermatozoa in a haemocytometer, a single-use calibrated chamber or a Makler chamber does not produce the same count. Similarly, changing the procedure for assessing normal sperm morphology from old WHO guidelines to the more recent WHO recommendations, which are based on stricter criteria, results in markedly different percentages of morphologically normal spermatozoa
Finally, fewer than half of the discussed studies considered inter-observer variability, including both occasional and intrinsic variability within the same pool of technicians and the changes in these pools over the years. In addition, few studies mention the existence of concomitant internal quality controls that are necessary to maintain satisfactory intra-individual and inter-individual homogeneity in semen assessment over time.
Fisch (2008) has some colorful commentary:
Obtaining human semen for scientific analysis is logistically difficult. As many authors have pointed out, the fact that semen is almost universally obtained by masturbation has placed profound limits on the ability of researchers to adequately study this issue. If collection of semen samples were as straightforward as obtaining blood samples, the nature of semen quality changes over time (if any) would have been determined decisively decades ago. A prospective, longitudinal study of semen parameters in a large, multicenter, randomized study of community-dwelling men, although time-consuming and expensive, would provide highly reliable data. Of nearly equal quality would be an analysis of a suitably sized population of randomly selected community-dwelling men analyzed by birth cohort. Unfortunately, neither of these high-quality observational tools has been used to investigate the phenomenon of semen quality because of the logistical and emotional obstacles posed by the means of obtaining semen in a timely and well-controlled manner.
However, Auger identify six (of their original seventy) studies that they say are extremely well done and suffer from none of these potential confounders. They say five of the six still show declining sperm counts, and believe that the effect might be real (they say there is no evidence it is global rather than limited to these five regions but I think if an effect happens in five regions, and there is only one region where it is not happening, it is fair to wonder whether it represents a broader trend). I interpret their conclusions as very cautiously pro-decline-hypothesis (Fisch remains against).
There is also a Harvard Gender Science Laboratory paper that the media has played up as attacking the sperm count decline hypothesis. But it is mostly written by Gender Studies professors, anthropologists, and philosophers, and mostly just says that it sounds sexist to say something bad might be happening to men (it also adds that since some studies have found the decline is higher in Europe, it’s racist for saying something bad is happening to white men). It makes a few of the points above about how science is hard and measurement error is common, but overall doesn’t make any points that Auger and Fisch don’t make better, and the authors seem very likely to be politically biased.
Did The Hypothesis Start By Mistake?
One interesting corollary of these studies being so noisy: as far as I can tell, basically every person who proposed this hypothesis before Levine et al was mistaken, and had no right to conclude this from their small samples. If they were right, it was only by coincidence.
Consider Nelson & Bunge, the seminal (sorry) 1974 paper that founded this field. They studied 390 samples, and compared to samples studied with a different technique, in a different part of the US, in 1951. Surely whatever differences they found are well within the usual range of noise?
But the hypothesis only reached the scientific mainstream in 1992, after the publication of the Carlsen et al meta-analysis. Fisch savages this in his paper, showing that with proper statistical techniques, it ought to have found an increase, rather than a decrease, in sperm concentration over the period studied.
Unless I’m misunderstanding this, it seems like to support sperm count decline, you’d have to claim that everyone who argued about it for the first forty years or so was working off of useless data, but by coincidence they happened to be right anyway.
There’s no reason this can’t be true, but it makes me suspicious.
Where Is The Decline Most Pronounced?
Levine et al don’t officially compare developed vs. developing world counts, but unofficially it looks like sperm count is declining faster in the developed than in the developing world. I can’t tell whether the difference is significant, and the decline in the developing world is either just above or just below traditional statistical significance depending on how you measure it.
Auger et al report that they found declining sperm count in:
83% of South American studies
64% of European studies
50% of Asian studies
40% of Australia/New Zealand studies
33% of US studies
Just eyeballing it, Scandinavian countries have less sperm decline than Central European, and Japan/Korea have less sperm decline than China. Chinese data showed some extraordinarily fast declines over the space of just 5 or 6 years, although China is sometimes known for having bad studies that prove overly interesting things, and other Chinese studies found no change.
This Qatar study compares Middle Easterners to non-Middle-East immigrants (mostly African and Indian). The Middle Easterners had significantly lower sperm concentration (37 vs. 30). Auger et al also found that Middle Easterners had some of the lowest sperm counts in their sample, with Egyptians having the lowest count measured. It’s unclear if this represents a decline or if they just started out lower.
A study of four US states found the highest sperm concentration in New York (103 million), and the lowest in Missouri (59 million). Auger et al found that Parisian sperm count was highest in city center and lowest in the outlying districts, and some people have concluded a more general principle that the decline is worse in rural areas.
In the US, black people seem to have lower sperm count than whites or Latinos.
Given how hard it is to find this effect at all, we should be suspicious that all of these differences are fake, and that actually we don’t know anything about where sperm decline is faster or slower.
What About Animals?
Many farm animals are bred through artificial insemination. That means we have very good data on farm animal sperm over long periods of time.
Some articles try to vaguely suggest animals have lower sperm count, citing studies on related topics that never quite get around to finding animals have lower sperm counts, for example this one from The Conversation.
Actual animal studies tend to find inconsistent results. For example, bull semen was getting worse from 1965 - 1980, but got better again from 1980 to 1995. Horse semen sperm count in England and France has stayed the same or maybe even improved.
Overall there doesn’t seem to be convincing evidence this is happening in animals, although given how noisy human studies are I don’t know if we should conclude anything from just three.
A commenter who works with farm animals says that as artificial insemination has become more popular, breeders have selected bulls more and more heavily for excellence at semen production, which potentially confounds these results.
If Sperm Count Is Declining, What Could Be Causing This?
The hypotheses I’ve seen are:
Plastics
Pesticides
Sunlight and circadian rhythm
Diet and obesity
Porn
Going in order:
Plastics are sometimes “endocrine disruptors”. They mimic reproductive hormones, causing the reproductive tract to be getting random signals all the time and develop incorrectly. This is probably the most commonly cited hypothesis.
(a plastics engineer in the comments wants me to clarify that most of the offending chemicals are technically plasticizers - substances added to plastic to change its properties - and not the plastics themselves. Phthalates are an example of this; BPA is a counterexample).
I can’t find any great studies testing this hypothesis, although there are a few weak ones with very small sample sizes finding effects of plastic exposure on sperm motility.
If sperm counts really did decline between 1951 and 1974, as the Nelson & Bunge, 1974 paper suggests, it would be hard for plastic to cause this, since plastics were still rare for most of this time period. But as I mentioned above, maybe this paper was a fluke that got it right by coincidence.
This is Our World In Data’s map of plastic waste per capita. It’s actually not a bad match for the geography of sperm count decline, though it’s not amazingly perfect either.
Pesticides can also be endocrine disruptors. This is a good match for the “Missouri is worst US state” result, and in fact that same study separates Missourians by pesticide exposure.
They find that “cases” with lower-than-average sperm concentration have more than twice the blood level of some pesticides than “controls”, p = 0.0007. But this is in a sample of only 50 people, all in Missouri.
Two meta-analyses (1, 2) find that 28 of 37 studies investigating a pesticide/sperm count correlation have found significant results, with some of the others only barely missing significance. The usual study designs are:
Compare people occupationally exposed to pesticides (eg farmers) with people who aren’t
Compare sperm quality with pesticide metabolites detected in the blood.
Compare sperm count in people who eat a lot of fruit to people who eat very little.
There is probably publication bias in this literature, and nobody has done even basic tests to look for it, but overall I find it pretty suggestive.
Sunlight and circadian rhythm are known to affect sperm count (did you know that men produce more sperm in winter than summer, and any study that doesn’t account for this is potentially confounded?) People working office jobs and staring at screens all day have worse-defined circadian rhythm, and maybe this is bad in some way.
Sperm quality displays a classic pattern where it seems correlated with Vitamin D, but supplementing Vitamin D does not improve it. This can either mean it is correlated with some other sunshine-related process we don’t understand, or that Vitamin D is a more general marker of (the relevant facets of) good health.
Only one team did the study I wanted - seeing if sperm count was lower in workers with night shifts or confusing shifts than in more regular workers; they concluded it was, but I find their results kind of weak and unconvincing.
Obesity and bad diets can impact sperm count. But the US, a world center of obesity, seems to be doing better than many less obese countries, and countries like China and France that have maintained relatively low rates of obesity and overweight seem heavily affected. If modern diets are the problem, then it has to be something more insidious than obvious you-are-very-fat obesity - unless you want to use the “all regional comparisons are too low sample size for us to care” card.
Porn hasn’t actually been proposed as a cause of declining sperm count as far as I know, but I found myself wondering about it when writing this piece. Doesn’t frequent masturbation decrease sperm count?
Yes, somewhat, for a few days. But people doing official studies usually ask men to abstain for a few days before giving samples, and when they don’t, they adjust for this as a confounder. So if this were a cause, it would have to be some kind of long-term negative effect separate from the well-established effect where you ejaculate all your sperm and can’t make new ones for a few days.
There is one extremely weak study finding evidence for such an effect. But also, many sources find that Middle Eastern countries watch the most porn, and these are also the countries with lowest sperm count. Obviously an ecological argument like this is extremely weak, even before we get to the problem where all cross-country comparisons might be bunk.
Other things that don’t get their own paragraph:
Marijuana decreases sperm count and people use it a lot more recently
Sitting decreases sperm count and more people have sitting jobs
Cell phone in your pocket
Heat is known to decrease sperm count, are we getting more of it for some reason? Global warming? Heated buildings? Laptop on your scrotum?
Women are using hormonal birth control, and men are either absorbing it through the water supply, or missing cues of fertility that would otherwise increase sperm production through to some galaxy-brained evo psych daisy chain.
Conclusions And Predictions
To grind my usual axe: this is the kind of complex issue that makes me wary of bias arguments and the “misinformation” framing.
If it turns out this was real all along, people will point to the hundreds of studies demonstrating it and prestigious scientists pushing it. Doubters will be compared to global warming denialists, ignoring science in order to continue their fantasy of consequence-free pollution.
And if it turns out this was totally fake, people will talk about how this was a classic panic of fragile masculinity (“our precious bodily fluids!”). They’ll place it alongside ivermectin in the annals of “don’t trust small noisy studies”.
In retrospect, it will feel obvious that one side was right all along and the other was laden with junk science, biases, and all the classic red flags for conspiracy theories. We’ll be told we should have “trusted the experts” - either experts like Levine and Swann saying it’s real, or experts like Auger and Fisch saying it’s overblown.
But right now, not knowing which side is right, we don’t have any of these easy outs. We have to actually reason under uncertainty!
I’m not actually very good at this in this situation, and I’m pretty split about how concerned to be. Trying to turn this into concrete predictions, with a market for each:
1: In twenty years, the best evidence will suggest that sperm counts have been substantially declining across most of the world: 50%
Auger and Fisch make great points about confounders and measurement difficulties. Nobody denies how noisy these data are. I think the case in their favor is that there are so many studies that you’d need a strong directional bias to explain the strong directional finding - plus the sheer magnitude of the effect, from counts of 100 million + in the Fifties to ~40 million today, is impressive.
I wrote this post at the same time I wrote my response to Alexandros Marinos on ivermectin. If I applied the same hyper-skeptical eye to these studies that I apply to the ivermectin studies, they fail. But I admitted I was more cynical than usual about the ivermectin studies because of the many large RCTs that found no effect. Should I be more forgiving here? I’m not sure.
2: In twenty years, the best evidence will show very substantial (>one quarter) declines in fertility rate (relative to couples trying equally hard to conceive in the past) due to decreasing sperm count, in at least one country: 20%
If sperm counts are declining as fast as Swann and Levine think, this should definitely happen.
So why is my number for this prediction so much lower than for the one above? Partly because the decline could be sublinear. Partly because the decline could stop - either because we identify the cause and correct it, or for more mysterious reasons. But partly it’s just an unjustifiable penalty for something that it seems very hard to imagine happening.
3: Conditional on a consensus 20 years from now being that sperm count was declining, scientists will believe the most important factor is:
Plastics: 25%
Pesticides: 30%
Sunlight and circadian rhythm: 2%
Diet and obesity: 13%
Porn: 5%
Something else: 25%
Pesticides mostly going off the many studies supporting this hypothesis; plastics mostly going off superficial plausibility and the number of scientists talking about it.
[Thanks to paid subscribers for reviewing an earlier draft of this post.]
Evolution doesn't operate that quickly.
Even supposing that ten people currently have some rare mutation that allows them to keep natural sperm count, evolution would have to go through "everyone except those ten people fail to reproduce" -> "those ten people's descendants repopulate the earth", which doesn't really seem like a "business as usual, no need to worry" scenario.
Most traits are polygenic! Natural selection can act on the diversity that is already present, it doesn't depend on "rare mutations", there are already hundreds of polymorphic loci. Thinking in terms of "rare mutations" is appropriate for novel traits (where did wings come from?), but not here.
My prediction is that after the first generation where a significant enough minority gets into the problematic range, the trend will slow down, with a delay of one generation. Eventually it might even revert.
It's quite possible that nuclear weapons will be used, but not used on a grand scale. They might be comparable to conventional wars and other disasters.
Quite true. In the case where they were used, in WWII, two of them were used.
Phil Tanny's whole concern seems misplaced to me. Sure, there is violence tied to specifically male psychology and biology. There are roughly 17,000 homicides per year in the USA, and roughly 90% of the killers are male. This doesn't threaten to bring down civilization. The sorts of events with huge death tolls - wars, Mao's great leap corpseward, etc. are not matters of momentary anger and poor impulse control. They are matters of institutional structure and game theory and ideology. If every national leader were female I doubt that they would change much.
Look, leaders like Prime Minister Margaret Thatcher have participated in wars. You have a point about individual male violence. You have demonstrated nothing about whether that predicts anything about national level violence, which is where the bulk of the butcher's bill comes from. Can you point to anything predicting national level violence depending on the sex of the national leader?
JFK deciding what to do about the Cuban Missile Crisis in a National Security Council meeting is a very different animal than a murder in a bar fight. As I said, I think that the former is a matter of institutional structure and game theory and ideology. Do you really think that Thatcher would have made more peaceful decisions than Kennedy because of her sex?
"Which gender is leading the wars, revolts, rebellions and insurrections etc all over the world, for thousands of years?"
Yes, it is primarily, but not exclusively, male.
"I agree that women can be violent. But the scale of their violence is radically smaller than that of men."
You could make a more plausible case by saying that women are less frequently in control of potentially violent institutions. When they _are_ in control, as in Thatcher's case, you haven't shown any evidence that they choose institutional actions that are less violent than men choose. Do you have any such evidence?
Look, the kind of interaction at a decision-making meeting is very different from a murder in a bar fight. They speak. They weigh evidence. They discuss options and pros and cons. They ask questions. They formulate novel combinations of options. It is much closer to a puzzle solving process than to shoving a knife into someone in a fit of rage. I haven't seen national level decision making meetings, but, from what I've seen of corporate decision making meetings, male and female participants appear to behave very similarly.
It's hard to say-- we don't know how much the major atrocities are based in male-style anger acting in an environment it was never evolved to fit.
One hypothesis (I really don't know) is that if all the leaders were women, wars would be fewer but more deadly because women would be more practical and only fight when there's a clear reason. Just a guess, though.
Could be - though I'm not sure how many of the national scale violent events are driven by anger at all. From what I've seen of decision making meetings (admittedly at much lower levels, and in a corporate environment), they look much more like puzzle solving than like bellowing in anger. The answer that the puzzle solving comes up with may itself be murderously violent, "Let's invade the Bay of Pigs!", but I suspect that a large chunk of the motivation of the participants in those meetings from minute to minute is to look intelligent in front of their co-participants.
My guess is that anger differs substantially between men and women (or at least physical manifestations of it do).
My guess is that cool calculation differs very little between men and women.
There's a relationship, but showing it's causal is difficult. There's also a relationship between emptying cat litter boxes and risk-taking.
FWIW, men generally take more risks of encountering violence than do women, so if you survey humans, there is naturally a relationship to level of testosterone. This doesn't prove that it's causal, as there are LOTS of other differences. You run into this problem even among sub-groups of men. Smaller men often are perceived as taking fewer risks, but the risks they take aren't the same as those that would be encountered by a more muscular man (and muscles ARE related to testosterone level).
Your argument COULD be right, but proving that it's causal in the implied direction would be quite difficult.
"Save humanity by killing half of it" is the villain plan of multiple stories. "Save humanity by killing all the men" is straight out of The Vampire Chronicles: Queen of the Damned.
What I'm saying is, this line of thought will end in you getting your organs eaten by psychics.
Okay, but to be fair you did write ~ 7 paragraphs worth of dreck between your original comment and subsequent replies that we've shared the misfortune of reading. You're way past your quota of warranted attention already.
"In this ongoing article series we’re exploring the possibility of bringing on an era of world peace by establishing a world without men. It’s been proposed that doing this would radically reduce violence, and generate a huge peace dividend which could improve the human condition even further."
Well, yeah: killing off the entire human population in a couple of generations because no new source of sperm = no new humans *would* result in a more peaceful world (if we disregard animal violence) but species suicide is a bit drastic, unless you're an anti-natalist who does think humanity should go extinct.
Also, women are not more peaceful and cuddly and less aggressive than men, so the alleged peaceful utopia won't happen. Margaret Thatcher had no problem with the Falklands War, and Queen Victoria didn't tell her forces to stop expanding the Empire.
Or look at Joanna Russ' story "When It Changed":
https://en.wikipedia.org/wiki/When_It_Changed
"Janet Evason lives on Whileaway, an all-female human colony planet whose inhabitants produce offspring by combining ova because all their males died in a plague 30 generations earlier. When male astronauts arrive from Earth, they say that Earth has become genetically deficient and tell her that they would like to reproduce with women. Janet's wife tries to kill the astronauts; Janet stops her, but realizes that their very existence will change Whileaway society forever.
In the afterword, Russ states "When It Changed" was written to challenge ideas in science fiction that had not, at the time of writing, been addressed. These ideas were related to the way women — and societies consisting solely of women —were handled by writers who are male. She wrote:
I have read SF stories about manless worlds before; they are either full of busty girls in wisps of chiffon who slink about writhing with lust (Keith Laumer wrote a charming, funny one called "The War with the Yukks"), or the women have set up a static, beelike society in imitation of some presumed primitive matriarchy. These stories are written by men. Why women who have been alone for generations should "instinctively" turn their sexual desires toward persons of whom they have only intellectual knowledge, or why female people are presumed to have an innate preference for Byzantine rigidity, I don't know."
Excerpt from the story:
"Katy and I have three children between us, one of hers and two of mine. Yuriko, my eldest, was asleep in the back seat, dreaming twelve-year-old dreams of love and war: running away to sea, hunting in the North, dreams of strangely beautiful people in strangely beautiful places, all the wonderful guff you think up when you're turning twelve and the glands start going. Some day soon, like all of them, she will disappear for weeks on end to come back grimy and proud, having knifed her first cougar or shot her first bear, dragging some abominably dangerous dead beastie behind her, which I will never forgive for what it might have done to my daughter. Yuriko says Katy's driving puts her to sleep.
For someone who has fought three duels, I am afraid of far, far too much. I'm getting old. I told this to my wife."
And to quote more from Russ' afterword, the words of a real woman and not some imaginary Eternal Feminine, Mr. Tanny:
"In my story I have used assumptions that seem to me obviously true. One of them is the idea that almost all the characterological sex differences we take for granted are in fact learned and not innate. I do not see how anyone can walk around with both eyes open and both halves of his/her brain functioning and not realize this. Still, the mythology persists in SF, as elsewhere, that women are naturally gentler than men, that they are naturally less creative than men, or less intelligent, or shrewder, or more cowardly, or more dependent, or more self-centered, or more self-sacrificing, or more materialistic, or shyer, or God knows what, whatever is most convenient at the moment. True, you can make people into anything. There are matrons of fifty so domesticated that any venture away from home is a continual flutter: where's the No Smoking sign, is it on, how do I fasten my seat belt, oh dear can you see the stewardess, she's serving the men first, they always do, isn't it awful. And what's so fascinating about all this was that the strong, competent "male" to whom such a lady in distress turned for help recently was Carol Emshwiller. Wowie, zowie, Mr. Wizard! This flutteriness is not "femininity" (something men are always so anxious women will lose) but pathology.
It's men who get rapturous and yeasty about the wonderful mystery of Woman, lovely Woman (this is getting difficult to write as I keep imagining my reader to be the George-Georgina of the old circuses: half-bearded, half-permanentwaved). There are few women who go around actually feeling: Oh, what a fascinating feminine mystery am I. This makes it clear enough, I think, which sex (in general) has the higher prestige, the more freedom, the more education, the more money, in Sartre's sense which is subject and which is object. Every role in life has its advantages and disadvantages, of course; a fiery feminist student here at Cornell recently told an audience that a man who acquires a wife acquires a "lifelong slave" (fierce look) while the audience justifiably giggled and I wondered how I'd ever been inveigled into speaking on a program with such a lackwit. I also believe, like the villain of my story, that human beings are born with instincts (though fuzzy ones) and that being physically weaker than men and having babies makes a difference. But it makes less and less of a difference now.
Also, the patriarchal society must have considerable survival value. I suspect that it is actually more stable (and more rigid) than the primeval matriarchal societies hypothesized by some anthropologists. I wish somebody knew. To take only one topic: it seems clear that if there is to be a sexual double standard, it must be one we know and not the opposite; male potency is too biologically precious to repress. A society that made its well-bred men impotent, as Victorian ladies were made frigid, would rapidly become an unpeopled society. Such things ought to be speculated about."
Dude, I'm a woman. I went to school in an all-girl school. I interact mostly with women in my working life. I know what women are like.
If you want to preserve your fantasies about primitive matriarchal utopias, go right ahead, but don't try to tell real women what we are really like because you, as a man, really know better.
Cordwainer Smith wrote "The Crime and Glory of Commander Suzdal" which involved a planet of only males (I can't remember how they reproduced). It was even more problematic than typical all-female SF planets. He didn't have much detail on it, though, as it was from the POV of a space explorer attacked by them.
Looked it up online as I remember the story but didn't remember the exact method. Here it is (and with news of uterus transplants now, very prescient in its way):
https://gutenberg.ca/ebooks/smithcordwainer-crimeandthegloryofcommandersuzdal/smithcordwainer-crimeandthegloryofcommandersuzdal-00-h.html
"Before she died, Dr. Kraus had worked out a carefully programed genetic system. Little bits of the men's tissues could be implanted by a surgical routine in the abdomens, just inside the peritoneal wall, crowding a little bit against the intestines, an artificial womb and artificial chemistry and artificial insemination by radiation, by heat made it possible for men to bear boy children."
But goodness gracious me, the attitudes in the story would get the man purged from society today were he alive. It's very old-fashioned about the attitudes to men and women, and I did find it amusing that the notion that there might be *women* in space is something that never dawns on them - although the general idea seems to be that there aren't any other life-forms in the galaxy, at least none they've encountered:
"The official spat out his offer: "Dancing girls. WOMEN. Concubines. Don't you want any of those? We could even cube your own wife for you and print her mind on a cube for you. That way she could be with you every week that you were awake."
Suzdal looked as though he would spit on the floor in sheer disgust. "Alice? You mean, you want me to travel around with a ghost of her? How would the real Alice feel when I came back? Don't tell me that you're going to put my wife on a mousebrain. You're just offering me delirium. I've got to keep my wits out there with space and time rolling in big waves around me. I'm going to be crazy enough, just as it is. Don't forget, I've been out there before. Getting back to a real Alice is going to be one of my biggest reality factors. It will help me to get home." At this point, Suzdal's own voice took on the note of intimate inquiry, as he added, "Don't tell me that a lot of cruiser commanders ask to go flying around with imaginary wives. That would be pretty nasty, in my opinion. Do many of them do it?"
"We're here to get you loaded on board ship, not to discuss what other officers do or do not do. Sometimes we think it good to have a female companion on the ship with the commander, even if she is imaginary. If you ever found anything among the stars which took on female form, you'd be mighty vulnerable to it."
"Females, among the stars? Bosh!" said Suzdal.
"Strange things have happened," said the official.
"Not that," said Suzdal. "Pain, craziness, distortion, panic without end, a craze for food—yes, those I can look for and face. They will be there. But females, no. There aren't any. I love my wife. I won't make females up out of my own mind. After all, I'll have the turtle-people aboard, and they will be bringing up their young. I'll have plenty of family life to watch and to take part in. I can even give Christmas parties for the young ones."
"What kind of parties are those?" asked the official.
"Just a funny little ancient ritual that I heard about from an Outer Pilot. You give all the young things presents, once every local-subjective year."
"It sounds nice," said the official, his voice growing tired and final. "You still refuse to have a cube-woman on board. You wouldn't have to activate her unless you really needed her."
"You haven't flown, yourself, have you?" asked Suzdal.
It was the official's turn to flush. "No," he said, flatly.
"Anything that's in that ship, I'm going to think about. I'm a cheerful sort of man, and very friendly. Let me just get along with my turtle-people. They're not lively, but they are considerate and restful. Two thousand or more years, local-subjective, is a lot of time. Don't give me additional decisions to make. It's work enough, running the ship. Just leave me alone with my turtle-people. I've gotten along with them before."
And yes, Suzdal does get trapped by a fake distress call delivered in the voice of a woman. But that's not the worst of it; the planet is populated by what we would now call trans men, and they're gay (by necessity), and there would be burning in effigy at Pride parades for the likes of this:
"Mankind could not meet the terrible people of Arachosia without the people of Arachosia following them home and bringing to mankind a grief greater than grief, a craziness worse than mere insanity, a plague surpassing all imaginable plagues. The Arachosians had become un-people, and yet, in their inner-most imprinting of their personalities, they remained people. They sang songs which exalted their own deformity and which praised themselves for what they had so horribly become, and yet, in their own songs, in their own ballads, the organ tones of the refrain rang out,
And I mourn Man!
They knew what they were and they hated themselves. Hating themselves they pursued mankind.
Perhaps they are still pursuing mankind.
The Instrumentality has by now taken good pains that the Arachosians will never find us again, has flung networks of deception out along the edge of the galaxy to make sure that those lost ruined people cannot find us. The Instrumentality knows and guards our world and all the other worlds of mankind against the deformity which has become Arachosia. We want nothing to do with Arachosia. Let them hunt for us. They won't find us.
...If the sun of Arachosia killed everything which was female, if the female fish floated upside down on the surface of the sea, if the female birds sang a shriller, wilder song as they died above the eggs which would never hatch, if the female animals grunted and growled in the lairs where they hid away with pain, female human beings did not have to accept death so tamely. The doctor's name was Astarte Kraus.
The human female could do what the animal female could not. She could turn male. With the help of equipment from the ship, tremendous quantities of testosterone were manufactured, and every single girl and woman still surviving was turned into a man. Massive injections were administered to all of them. Their faces grew heavy, they all returned to growing a little bit, their chests flattened out, their muscles grew stronger, and in less than three months they were indeed men.
Some lower forms of life had survived because they were not polarized clearly enough to the forms of male and female, which depended on that particular organic chemistry for survival. With the fish gone, plants clotted the oceans, the birds were gone but the insects survived; dragonflies, butterflies, mutated versions of grasshoppers, beetles, and other insects swarmed over the planet. The men, who had lost women worked side by side with the men who had been made out of the bodies of women.
...The human body, which had taken four million years on earth to grow, has immense resources within it, resources greater than the brain, or the personality, or the hopes of the individual. And the bodies of the Arachosians decided things for them. Since the chemistry of femininity meant instant death, and since an occasional girl baby was born dead and buried casually, the bodies made the adjustment. The men of Arachosia became both men and women. They gave themselves the ugly nickname, "klopt." Since they did not have the rewards of family life, they became strutting cockerels, who mixed their love with murder, who blended their songs with duels, who sharpened their weapons and who earned the right to reproduce within a strange family system which no decent earth-man would find comprehensible.
But they did survive.
And the method of their survival was so sharp, so fierce, that it was indeed a difficult thing to understand.
In less than four hundred years the Arachosians had civilized into groups of fighting clans. They still had just one planet, around just one sun. They lived in just one place. They had a few spacecraft they had built themselves. Their science, their art and their music moved forward with strange lurches of inspired neurotic genius, because they lacked the fundamentals in the human personality itself, the balance of male and female, the family, the operations of love, of hope, of reproduction. They survived, but they themselves had become monsters and did not know it.
Out of their memory of old mankind they created a legend of old earth. Women in that memory were deformities, who should be killed. Misshapen beings, who should be erased. The family, as they recalled it, was filth and abomination which they were resolved to wipe out if they should ever meet it.
They, themselves, were bearded homosexuals, with rouged lips, ornate earrings, fine heads of hair, and very few old men among them. They killed off their men before they became old; the things they could not get from love or relaxation or comfort, they purchased with battle and death. They made up songs proclaiming themselves to be the last of the old men and the first of the new, and they sang their hate to mankind when they should meet, and they sang "Woe is earth that we should find it," and yet something inside them made them add to almost every song a refrain which troubled even them,
And I mourn Man!
They mourned mankind and yet they plotted to attack all of humanity."
Suzdal's solution is ingenious, but it is also why he is sentenced for punishment.
Lois McMaster Bujold has the the delightful "Ethan of Athos", whose titular protagonist is the head obstetrician on an all-male planet. They have artificial "uterine replicators", because Bujold, but they still need eggs and that means maintaining ovarian tissue cultures. Obviously, the story is about what happens when this does not go smoothly, but there's a fair bit of background about how the society works when things are working properly.
For Bujold fans who don't already know about it, this is a side story of the "Vorkosigan" saga, featuring zero Vorkosigans but one (1) Elli Quinn, intelligence officer on detatched duty from the Dendarii Free Mercenary Fleet.
"If there were no men, we'd all be still living in huts." -- Camille Paglia
Men have also been responsible for >95% of the science, technology, mining, construction, and industry that have created the modern world of health and abundance, where the average worldwide life expectancy is 72 instead of 30. You want to talk about unspeakable horror shows? How about a world where parents lose a child every other year?
And how about mining and construction, aka actually building the physical world we live in every day? All the STEM in the world isn't worth anything if you can't make stuff with it.
Women have been just as ruthlessly prohibited from participating in the violence fields until pretty recently, basically one lifetime. If you're going to assume that relaxing the restrictions on women (and taking male competition out of the equation) will result in women achieving male-equivalent performance in science, technology, etc, then it seems only fair to assume that it will also result in their achieving male-equivalent performance in crime, insurrection, and war.
They are still responsible for most of everything that matters, despite women being preferred 2:1 in STEM.
If you're concerned about world peace, you might be interested to know that European queens have historically waged war 27% more often than European kings: https://www.economist.com/europe/2017/06/01/who-gets-into-more-wars-kings-or-queens
War has nothing to do with a playground fistfight. Just because girls don't usually punch each other in the face in grade 4, doesn't mean that women are better at unentangling the complex web of ideology, economic interests, balance of power dynamics, and domestic political concerns that lead to war.
Many Thanks! That is very helpful evidence.
That's the "Margaret Thatcher and Hillary Clinton" effect. Both of them were careerists who thought they needed to compensate for being women by being MORE warlike than men . . . Thatcher (Falkland Islands); Hillary Clinton: (Qaddafi) https://www.youtube.com/watch?v=6DXDU48RHLU
That's a just-so story. An equally plausible just-so story is that Thatcher and Clinton were simply warlike for the same reasons that men are warlike, which in turn is because war is the result of a complex web of ideology, economic interests, balance of power dynamics, and domestic politics, and those factors often make war desirable in the eyes of a country's leaders.
"violent men + knowledge explosion = game over"
The knowledge explosion already happened, rates of violence are down by extraordinary amounts, and we are still here.
As for eliminating men, there is no "we." The idea that human civilization is run by a single person who can unilaterally decide what's best for it is utopian nonsense. You can only get rid of men in the corner of the world you control, at which point that corner of the world would be thoroughly subjugated by societies that still have men. Even if you had superior military technology as a deterrent, societies with men would not only surpass you, but your society would be too afraid to use it, maintain it, or keep developing it.
This is why it amuses me that almost all of the people who love to speculate about genetic causes for differences in racial crime rates are men.
Nothing amusing there. We're all fully aware that men commit most crimes, but there's a big difference between removing men from your society (which is a wee bit difficult) and pushing back against utopian lies about race.
Plus, if you got rid of all the men, you'd have nobody left to think about--and address--harsh truths like the above, and the fact that a certain demographic of women commit even higher rates of murder than a certain demographic of men.
Are people masturbating more these days? Or more precisely: are men ejaculating more frequently these days? I feel like there must be some data on this. It's not immediately obvious to me that the increased availability of porn necessarily makes it so.
For sperm counts to seem lower, it doesn't need to be that the average man ejaculates more. It is enough that those who agree to participate in a study on sperm counts masturbate more. And what kind of people are willing to participate in such a study? Presumably men who have nothing against masturbating in a public setting. That is, men who are used to masturbating.
In the pre-internet era, men who had the habit to masturbate had to use their imagination, or the same old pornographic magazine all over again. Today those men have quadrillions of pornographic films to choose from. If that didn't make them masturbate more, it would have been a market failure of proportions.
They make men masturbate in public? I assumed they would have given the men and tube and told them to go home and collect the semen themselves.
Interesting question! Answering it requires reading the fine print of a number of studies and I haven't done that. I guess that if researchers allow people to handle their sperm themselves, people would refrigerate it at different temperatures during different amounts of time, making the whole experiment less accurate.
At least I know that for fertility treatments hospitals have a small room with a stack of porn magazines which are supposed to help hopeful future fathers to masturbate successfully. A man who had children that way told me about it.
I recently took a fertility test in the UK. I think it varies, but if you live close to a hospital they allow you to produce a sample at home. You're required to drop it off within a short time window after production, and to keep it close to your body to maintain the temperature.
Alternatively, they offer private booths at the hospital where a drop off isn't feasible.
Slightly different interpretation, but to participate in this study, you have to be comfortable with someone knowing you masturbate, even if it's a private room.
A highly religious or shy person, for example, might masturbate in private, but would not "admit" to it as easily as someone who is more comfortable with masturbation in general.
Scott mentioned samples potentially coming from people who had been selected for infertility issues. Which seems to imply it's not a self selecting sample
Yes, basically we have two groups who are likely to give their sperm away for research:
1. Men with fertility issues who are eager to get those fertility issues investigated.
2. Men who think "masturbate in a cup - get paid ten dollars" sounds like a good deal.
only ten? what kind of cheap w**** do they think I am? I demand $25
Make it 0.0001 cents per sperm cell, and the trend in the data will go away rather quickly.
No, it would be a lot stronger.
"Sorry, it seems sperm counts are declining fast. Here's a nickel."
I don't know what "w****" stands for.
From context I'm guessing the missing letters are hore.
Oh, right.
From the precise context, I thought it would be *anker.
It doesn't have the right number of characters, but still.
I also thought "anker"...
I'd imagine (hope?) these were couples that came in due to infertility and the issue was found to be with the other partner. Still not completely free of self-selecting taint, but not as bad as first blush.
"In the pre-internet era, men who had the habit to masturbate had to use their imagination, or the same old pornographic magazine all over again. Today those men have quadrillions of pornographic films to choose from. If that didn't make them masturbate more, it would have been a market failure of proportions."
Speaking for a friend: The friend said his earlier masturbation--say, in college in the 1970s--was done usually without "photographic assistance", and sometimes multiple times per day . . . Youth! Now in his sixties, the friend's masturbation has ready access to "photographic and video assistance" as desired . . . as needed?? The college-age masturbation was quicker, and "simpler." The young geriatric masturbation during the age of the internet is an up-and-down, "edging" experience which can go on for 90 minutes or more. I'm not sure how that effects sperm count.
We have a very important confounding factor here: age. Isn't it very common that it takes older men much longer to get off compared to younger men?
Speaking as someone who was once a young man who gained and lost access to pornography at various times, I'd say that statement was accurate irrespective of age (for at least some people).
I seem to recall a study saying it was the other way around.
I don't think porn per se is very significant - imagination is frankly better, since it's almost definitionally more tailored to one's personal taste - but different societal expectations around masturbation certainly might be.
I don't think porn addiction is as big a thing or issue as some media make it out to be, but it is _a_ thing and I can believe that milder forms of it are somewhat common, which should have an impact on masturbation frequency in at least part of the population.
Addiction aside: I'm sure people occasionally masturbated out of mere boredom (and that is definitely a thing, in women as well as in men) even before porn became widely accessible, but porn certainly facilitates that.
I don't think it's the porn alone (see below). Rather I'd point to the decreased moral approbation of masturbation. When my dad went to catholic school he was taught it was a sin, when I went to catholic school they didn't say that but there was still a sense it was kinda unclean. Now you don't get much of that at all.
Now many ppl who were taught this later reject the idea that it's wrong but it's alot harder to purge a sense of guilt/shame when doing it especially if you think of it as something only ppl w/o partners do (I used to hear bragging about not needing to masturbate). So such ppl might be quite willing to agree to a study (besides, even on the old don't waste seed teaching this was ok) but masturbate less frequently at home.
--
And re: porn it's not necessarily about addiction. I mean my wife thinks nothing of firing up porntube and having a quick orgasm if she's having trouble falling asleep. I suspect some men do the same now while they wouldn't have bothered without the easy porn.
Anecdata: I spent about 18 months in a "therapeutic boarding school" with no internet and no porn allowed (a non-zero but fairly small quantity of porn made its way on campus regardless). If anything, I think there may have been *more* masturbation simply because there was nothing better to do.
Yes, at some point boredom will increase masturbation especially in the young and horny but I think since the advent of TV most adults have long had sufficient entertainment to minimize the boredom effect.
Prediction #2 assumes reproduction works exactly the same in twenty years/has the same biological limitations. Totally putting aside various 'other' timeline-related concerns people have been animated about lately, this is a longer timeline than many reasonable-enough predictions for when human in vitro gametogenesis is 'viable enough', which would radically change the context of that and other problems.
The hope would be that the market converges well before twenty years.
If the singularity happens, friendly or unfriendly, it shouldn't have any effect on the market one way or the other in forecasts, because there is no sperm count if everyone is dead - or alternatively, if everyone lives in a beautiful upload utopia, I don't think we'll leave child health and development up to random DNA carrier tadpoles.
Your image of "the Singularity" is different from mine. E.g. I don't expect uploads to happen, except, perhaps, at the point of death. ISTM that even after a Singularity event, detailed mind readout will be a destructive process. Simulated uploads, however, may be quite common.
So for this argument the question would be "What effect will highly developed virtual reality have?". That might well result in reduced sperm count from many different variables, but the effect on reproduction would be due more to the lack of physical access. (I don't remember "The Machine Stops" addressing that point.)
Prediction 2 also allows less time for consensus to form - if sperm counts continue to decline, there's 20 years before market resolution for studies to prove it. if fertility only begins to sharply decline in X years, there's only 20-X years for studies to find it. Science is slow - it is quite plausible to believe that fertility will begin to decline in eg 15 years and there won't be scientific consensus on it in 20 years.
I had the good fortune to be in a room with fertility doctors not long ago, and here a few random takes:
- fertility almost always an egg problem, not a sperm problem - plenty enough sperm left for fertility at this point
- declining counts may or may not be real, but they tend to argue against it. Why, because sperm count varies a lot from day to day. Personally this make me inclined to believe that masturbation frequency / "porn addiction" may have more to do with it than medical reality
- vitamin D is a very real factor in egg quality. Egg quality can be shown to relate to the amount of body coverage in Middle Eastern women (!!) and current egg quality in 25 year olds in the middle East is more like what used to be seen in typical 40 year olds. Indoor life with a/c and body covering to blame. What does that mean for sperm, well, not so outlandish that similar factors may be at work.
- increasingly off topic, overall fertility: once again Middle Easterners these days seem to get married (often arranged) and then head straight to the IVF center. No one even tries to have sex anymore.
YMMV.
This is fascinating info, and not readily accessed by those not in the know. Do you have any other ideas that you picked up during this meeting?
Let me see... more on the details. The decline in Middle Eastern egg quality also has to do with endemic cousin marriage. And, evidence on the body-covering angle was given by a published paper that compared the exact shape and size of women's face and body coverage by country, with egg quality.
Very interesting! Thank you. It's always useful to see a problem from another perspective, in this case a cultural one.
"The decline in Middle Eastern egg quality also has to do with endemic cousin marriage."
That is surprising. I thought cousin marriage has been the norm there for at least the last millenium - my intuition would be that either effects of that on egg quality should have plateaued by now, or egg quality should have reached abysmal levels a long time ago. But seeing how many middle eastern countries have a high population growth, it obviously hasn't?
Same thought crossed my mind. I can only speculate that the Vitamin D issue created by indoors living due to A/C, might have exacerbated a pre-existing problem. But really... I don't have any data here.
It was, but historically, there was revolution/warfare every 3/4th of a century in Arabia, leading, to, let's say, 'women reallocation', which had the fortunate side effect of preventing runaway inbreeding.
See Ibn khaldun, scholar's stage. Arabs weren't blessed by geography.
Without having seen any of this research, I note that this sounds like it could largely be explained by the bias of those reporting the issues if there isn’t a careful design and agreed standard before gathering the data. For example, a society that is more biased against women will produce medical staff more inclined to blame ‘the egg’ rather than ‘the sperm’, especially where this is being reported to the clients (where ‘poor sperm quality’ might be taken as an insult or threat, as might ‘poor egg quality’ but I doubt the staff will worry about that). And this is likely to correlate with requiring women to cover up more, and allowing them outside less.
Which isn’t to say that it sounds implausible: it does sound plausible. But it could also be very easily confounded, especially if it has been gathered by surveying people involved in fertility clinics rather than by testing egg and sperm quality themselves.
This wasn't from a survey, these were qualitative comments by people running these clinics. It came unprompted during a session where a technology provider was demoing a device to improve the odds on the male side. They started saying, noted, this may work, but it's irrelevant because it is nearly never a sperm problem. From then on a discussion developed and the rest of the viewpoints came out. As to the atmosphere in the room, everyone talked about this like it's plumbing. They are commercial operators and get paid for successful fertilization. No incentive to bias science because of society or religion. It would hurt their business.
Ah! I was thinking especially of you saying
> evidence on the body-covering angle was given by a published paper
because I do think commercial operators discussing this are likely to be biased, especially when having a relaxed conversation. They get paid by people who decide to use their services, and continue using their services: that is their financial incentive. And they are ordinary humans, subject to all the normal biases of humans, choosing to live in particular societies.
If the solution to “sperm problem”, “egg problem”, “both problem”, and “neither is a problem, but I make money if you use me” is “use my IVF services”, then it doesn’t really matter if you default to recording “egg problem” for anything where it isn’t obviously and only a sperm problem, except that maybe recording that makes it more likely that clients use your services and continue to use them. And we know (as seen in Scott’s investigation of research into telepathy) that the beliefs of the person running a study can affect the results, even when you cannot see how they could possibly do so, even when they are totally honest.
Hence, while I completely agree it is plausible, I also think it is easily confounded, and would be interested in seeing the study you referred to, if either of us happen across it.
I saw the paper at the time but I don't have the reference. Cursory search at Google gives this: https://www.thenationalnews.com/uae/lack-of-vitamin-d-lowering-fertility-in-gulf-doctors-say-1.194882 , this https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9422066/ . This site here claims 90 % female infertility in UAE due to lack of sun: https://www.globenewswire.com/en/news-release/2022/10/06/2529571/28124/en/UAE-In-Vitro-Fertilization-Market-Female-Infertility-Rate-of-90-Driving-Demand.html
Hmmm. That paper says
> the levels of vitamin D are not related to the criteria of eggs such as the number of eggs and the maturity rate (MR) of eggs, but they are correlated in a statistically significant manner with the fertility rate (FR), and at the same time the levels of vitamin D in the blood were completely independent of the clinical pregnancy rate (CPR).
It seems to have chosen women specifically who had no known female reproductive system reason to struggle to conceive, attempting to conceive with a man where there definitely was a reason involving his sperm (that was part of the inclusion criteria), found a whole load of things were not statistically significant and one thing (the fertility rate, but not the pregnancy rate) that looked statistically significant, then partly explained it by citing the increased egg maturation rate which it had found was not statistically significant! I honestly think you could equally use it as evidence that men whose wives have less vitamin D have sperm that is less good at fertilising eggs, for whatever convoluted reason.
If that’s the currently available evidence from this population, my estimate of how likely it is that vitamin D affects egg quality has slightly decreased. But I’ll look out for other research: I’d actually quite like there to be better evidence suggesting that vitamin D affects the female reproductive system (I think there is some evidence, but not around egg quality), for personal reasons, but not as much as I want my beliefs in this area to be accurate.
That's one out of the 3 papers I picked at random within 20 seconds of search. The newswire article talks about eggs specifically. Others more generally about fertility. If you do a Google search it does give you a plethora of egg related results.
Sorry, I saw you cite two news articles and a paper, by the look of it, so I looked at the paper. Were the news articles reporting on separate papers, which I can look up? I’m not particularly interested in news articles on this sort of topic, as I find they can bring negative information.
I just wanted to give some context to get the ball rolling if you want to do some search yourself. Really, I only got my story of the IVF doctors as "food for thought".
I'd guess that if anything, cousin marriage was *more* endemic in the past than today, not vice versa?
The sunshine deprivation hypothesis brings to mind the higher latitudes, which should accordingly suffer from horrible problems with egg quality. During the cold seasons women walk around totally covered, and even if they have some parts of the face sticking out, there won't be much sun anyway, at least where I live. UV levels way low.
Is it possible that the wedding->IVF thing might be to do sex selection? I know India went the full mile and criminalised sex selection because everyone was selecting for boys and they were worried about demographic collapse.
it might. The doctors were more inclined to say that it had to do with pressure from parents to conceive ASAP, and that the couples were often arranged marriages between cousins, so, umm, the passion may be lacking too.
> - fertility almost always an egg problem, not a sperm problem - plenty enough sperm left for fertility at this point
Swan argues against this in Count Down:
>The recent decades have seen a substantial change in perspective, at least in the scientific community, as it has become increasingly recognized that men contribute to a greater proportion of infertility cases than previously believed. Male reproductive issues are currently thought to cause approximately one-quarter to one-third of infertility cases, equal to the proportion of female reproductive challenges. The remaining cases of infertility stem from a combination of male and female factors—perhaps a woman is slightly subfertile (because she has irregular ovulatory patterns, for example) and her male partner is also a bit subfertile (due to reduced sperm motility), so they have trouble conceiving.
I don't have the expertise to say who's right but it doesn't seem to be as clearly settled as those doctors made it sound.
I can only report what I hear. They were MDs that had become IVF clinic owners/operators and some were active researchers. So they were clearly practitioners. Their guesstimate was, 95% is an egg quality issue. Of course they're in IVF so they tend to focus on issues occur with the gametes, sperm and egg. Say if you have infertility due to chronic ED on the male side, lowered sex drive, or what have you, that's not a sperm problem but "epidemiologically" a male problem. Perhaps that explains the discrepancy. Maybe one should reword it as "usually not a sperm issue but an egg issue, or else, a wider relationship issue".
Is there a chance they meant "rarely a sperm problem for the clinic"? It possible an IVF clinic can do a lot more with a few thousand sperm than nature can; however in either case there's only a few eggs involved.
I wonder if this won't depend in part on how long people try before going to get help. You could easily imagine that there's a fair frequency of sperm related fertility lowering but that it rarely reduces the rate by more than 80% and most people just try long enough to overcome that before seeing a doctor. Thus, depending on how you define your study population or the willingness of a population to see a fertility doc you get different values.
>plenty enough sperm left for fertility at this point
So what is the minimum amount required before the odds of successful fertilization drops significantly? I vaguely remembering hearing or reading somewhere that immune cells get some of the sperm as they travel, but when even the minimal count is still in the millions, and you only need one to reach the egg. I have a hard time believing white blood cells make that much of a difference...or are there other factors that can prevent sperm from reaching the egg?
Don't be too sure "you only need one to reach the egg". I've read some articles that implied that sometimes sperm need to cooperate for any of them to be successful. Not only during the swimming, but there's a barrier around the egg that (at least) one sperm breaks to allow another sperm to penetrate.
Well, this could be wrong. It was in (IIRC) Science News, so it was popularized. OTOH...
"The Arab world has one of the highest rates of genetic disorders globally" - to quote Wikipedia. Should affect eggs/sperm. Ofc, it is those cousin-marriages over generations in the same tribe , due to inheritance-rules. https://en.wikipedia.org/wiki/Genetic_studies_on_Arabs#:~:text=The%20Arab%20world%20has%20one,%2C%20and%20Niemann%2DPick%20disease.
Interesting that you attribute the vitamin D link to indoor living and air-conditioning, rather than shifts in cultural norms around covering up - the shift from covering hair to covering everything but the face to covering the face too would seem to drastically reduce the amount of sunlight a body is exposed to. If one were inclined to investigate the relative contributions of the two effects, I'd expect the "aircon" explanation to be mostly gender neutral while the "culture" explanation is strongly gendered, so one could compare the relative declines in male and female vitamin D levels
Perhaps that came across so later, but in my initial post I mentioned the paper I saw, which did indeed attribute much of the change covering up everything in women.
Porn might affect sperm counts but not fertility rates -- since couples who are trying hard to conceive might be foregoing porn in favor of the real thing.
What happens if you change X axis to study quality instead of year, and Y axis to difference in count from comparison cohort?
Have someone neutral grade each study by quality, and see if there’s correlation to claim and effect. If the poorer the study, the bigger change in sperm count is found, that might indicate bias , likely unintentional.
What about the similar decline in testosterone?
Also, the “taint” distance studies while we’re at it.
Ever since I heard about these on Joe Rogan's podcast, I've really wanted Scott to do a deep dive on the topic.
"Taints, much more than you wanted to know" really sounds like the next hit piece.
Is that like the popehat rant version of digit ratio?
That is partly because men are smoking less and cigarettes increase testosterone.
do we know that this is the case and not just that men with higher test start smoking?
>cigarettes increase testosterone
If this is really the case, given how there seems to be a "bro science" trend around anything that has even the slightest anecdotal evidence towards it increasing testosterone (I remember when raw onions were big a few years back), I'm surprised "tobaccomaxxing" hasn't become a thing yet.
Anecdotally I have seen bro science people promoting cigarettes recently, although it seems half joking a lot of the time. I think it started when there was some evidence that they reduced the chance of catching COVID.
What about the similar decline in testosterone?
Are there studies about the amount if sperm ‘wasted’ vs ‘deposited’ into proper receptacles?
Will there be studies on ‘the size of the woman’s vagina’ or ‘the desiring affect women have on men’? These might have affect on the amount of sperm a man produces/ejaculates.
> It feels wrong to me to model this linearly, although I can’t explain exactly why besides “it means sperm will reach precisely 0 in thirty years, which is surely false”.
How about "it means sperm counts will be negative after thirty years, which is surely false"?
If I tell you that you're driving towards a cliff and will reach it in 20 minutes given your current speed and direction, would it be a valid argument for you to say "that can't be true, because it implies that in 21 minutes I will be floating in air, which is obviously silly"?
Obviously there's going to be some discontinuities once you reach the cliff. That doesn't mean my prediction up to that point can't be correct.
Obesity could be causing a decline in sperm count, but a decline in sperm count (well, testosterone) could also be causing some amount of obesity. Lower T -> harder to build muscle mass -> less calories being burned at rest.
It could also be caused by warmer buildings. If you're warm all the time, you convert your brown fat to white fat. Brown fat can burn lipids to produce heat, so you can burn calories just sitting or sleeping in a cold room.
When there's a whole bunch of possible causes, it's often wrong to select just one and say "That's the cause!". E,g, multiple pesticides all at sub-effective doses, can interact to produce drastic population drops. Yet each one of them when measured is at a safe level.
That's true! I'm not sure it disagrees with anything I said, though...I used the phrase "causing some amount of obesity", I never said "the cause!".
Lea, R., Byers, A., Sumner, R. et al. Environmental chemicals impact dog semen quality in vitro and may be associated with a temporal decline in sperm motility and increased cryptorchidism. Sci Rep 6, 31281 (2016). https://doi.org/10.1038/srep31281
I think you underweight how likely this is to be the result of decreased censure of porn/masturbation. Go back 30-40 years and lots of people still felt vaguely guilty about masturbating (even if intellectually u think it's ok feeling guilty and sad can be a buzz kill).
Yes, the doctors tell you to abstain but I can't even always remember to fast the day before my physical so ofc some of the subjects forget.
When I was younger I tried to donate sperm (liked idea of someone using it and could get some money) and I certainly forgot to refrain from masturbating for those days (ended up rejected bc not enough sperm)
And if you forget you won't want to sound like someone who couldn't even refrain from masturbating. I sure as hell didn't mention it when I came in. And how good is the evidence the effect is literally zero for everyone if you wait a few days?
--
And re: porn it's not that it's all porn addicts or something but I know ppl who think nothing of opening up porntube for a quick walk whenever they are having trouble falling asleep. Back in the day that would have been more work and probably less likely to be something so casual.
Wholeheartedly agreed. Plus there's an additional porn effect: the material that sperm clinics provide are usually DVDs, sometimes from the 90s. That can't keep up with modern porn, and sperm count feels like it should be related to intensity of ejaculation. (speculation based on 10 minutes of googling)
I'm not sure that matters. I doubt they stop you from bringing your phone in with you. I don't think many ppl use the provided materials anymore.
Ohh, nevermind. I guess back in the day most ppl didn't look at porn all that much so seeing it in the collection room was probably more exciting.
People keep talking about masturbation-related guilt in the past tense. This is still very much a thing and IMO we can’t expect very many people to be utterly and completely transparent, much less accurate, about when and how often they masturbate.
Well yes, but it's likely much less than it was in the past and we are looking at the differences. But yes, I agree that bc it's not exactly something ppl are proud of we can't always expect them to admit when they didn't follow the rules. I sure as hell didn't.
> Partly because the decline could stop - either because we identify the cause and correct it, or for more mysterious reasons. But partly it’s just an unjustifiable penalty for something that it seems very hard to imagine happening.
And partly it is a justified penalty for the most likely outcome being «be us damned if we have any idea either way, given all the confounders we had not even considered recording ten years ago»
Porn might not affect sperm count, but I wonder if it explains the recorded rise in erectile dysfunction and decline in sex frequency among young men. Seems like a plausible hypothesis, but the only study I found seems to debunk it.
https://www.nature.com/articles/s41443-022-00596-y
Seeing how the "social networks" are addictive, and how people who install them on smartphones turn to zombies, I don't think we need to look hard for explanations of "why young people spend less time doing X".
Probably yes for ED, but I'd bet sex frequency has more to do with how much the social environment has changed.
If the population declines and I believe it is sperm rates will be a small factor in that equation.
Disappointed the "other things" section didn't include "extremely fast evolution".
How would that work? Surely there's an inherent selection effect towards spark quality, almost by definition
Yes, but selection pressure might be decreasing in the modern era.
So in the olden days, people would have lots and lots of children, as many as possible often, and many of the children would die. So high sperm count would be useful.
But now many people decide how many children they want. So say a couple decide they want 2 children. With high sperm count that might happens in say 2 years, and with low sperm count it might happen in say 3 years. So the sperm count isn't that important, they end up with 2 kids either way.
Now it does matter somewhat, the guy might die after 2 years, and then the low sperm count guy would only end up with 1 child. But the selection pressure is probably less now than in the olden days.
But I don't think evolution is fast enough that this is a big factor yet.
I also think we'd only see this happen quickly if there was some big cost imposed by having high sperm count. Assumedly this wouldn't just be a "drift" sort of thing; for it to happen quickly there would need to be some sort of gain from evolving to produce lower sperm counts. I'm not a biologist, but if anyone with expertise wants to weigh in on the costs of having high sperm count, I'd be really curious
Could be something that seems completely unrelated. Like one gene gives high sperm count but also increases the chance of heart failure.
The filter-- which still might not be very fast-- would apply if a couple delays having children until the woman is late in her fertile years. At that point, if conception has become more difficult, she might have one or two fewer children than the couple was hoping for.
Even if we don't correct it, I think most potential causes listed there would level off (e.g. we're using more plastics than fifty years ago, but I don't think the rate of plastics use is still increasing), so if the problem is caused by one of the listed explanations we should be fine.
(Unless it's the porn one and AI-generated superporn makes it worse, I guess)
I wonder when that's coming out. I'm rather sure it will, but also that it will be expensive, so I'll never see it. (I'm a cheapskate.)
I should probably say here that before this blog post, I had thought this issue - that sperm counts had been declining - was, as a simple fact, completely uncontested, with no serious counterarguments even presented against this basic thesis. I've seen comments like "Sure, they're declining, but this is not a serious problem" or "Sure, they're declining, but why panic about it? Too many babies anyway" and so on, but this was probably the first thing I've seen that indicated they might *not* be declining, actually.
Is this just discussed differently in Finland and Finnish media than elsewhere?
Nope, same here. Score another point for "'Trust The Science' is not so easy because for a layperson there's no easy way to find out what The Science is actually saying, and the media through which you get your information, even if you're reading reasonably high-quality mainstream media and not the Daily Mail or whatever, are not guaranteed to give you a good overview".
The "reasonably high-quality mainstream media" can be the worst. The NYT is controlled by the US State Dept. and the Washington Post is controlled by the CIA. And both the State Dept and the CIA are captured by big corporations like Pfizer and the major defense contractors, so propaganda all-around. That leaves substacks--like this one--and there are a lot of them to parse.
No, no, you silly person: I have it on good authority that Pfizer is controlled by the NYT, the CIA is controlled by the State Dept, and all major defense contractors are controlled by the Washington Post.
People rag on the Daily Mail a lot because they don't like its politics, but I don't think it's especially problematic as regards science.
It's still a tabloid with a penchant for sensationalism, no? The Daily Telegraph and the Times have similarly right-leaning politics AFAIK (speaking from across the pond) but I'd take a science article I saw a link to in either of those far more seriously
C'mon, Science is full of politics. Okay, "Gravity" isn't very political. "Physics," and "Astronomy" aren't, but Medicine and Technology--for example--are!
haven't testosterone levels declined precipitously since then?
If these studies aren't controlling for age wouldn't aging populations, and later age having children, explain it fairly well? That would for why developing countries and China seem to have it worst.
We could check for correlation if we want. https://www.worlddata.info/average-age.php
With Japan showing a lower decline than China, I would think no.
Is this even a problem? As is hinted in the article human males overproduce sperms on a massive scale, probably a legacy from more polyandrous times when males were actually competing sperm to sperm. Anyway, the bottomline is that lower sperm count, if it is even real, should not translate into a general fertility problem until it gets way worse than today. The fact that this rather obscure subject is so popular in the news media probably has more to do with fragile male egos than actual science. (It is still a good thing of Scott to sort it out, of couse.)
Well, *if* the decline is continuing. Which is the point of the article.
FWIW, I think other factors will dominate. Which other factors depends on decisions that we make in the next decade (and ones I don't know about from the last decade). One that was suggested above was "AI generated super-porn". I'm not sure that won't be a problem. Certainly I don't understand (or realize the degree) to which people are attached to "Social Media". This despite the fact that I'm posting here. But if that limits human physical interactions, that could have a very strong effect of reproductive success.
It wouldn't surprise me if whatever issue causes declining sperm causes other bad things too.
I think both this and declines in testosterone are considered important not because of 'fragile male egos' but for their status as canaries in the sociological coal mine, possibly downstream of larger issues like water source contamination or unknown health effects from electronic devices.
Also, they're seen as possible causes of a worldwide decrease in traditional masculine values and behaviors. It seems extremely reasonable to be concerned.
You don't mention it, but there's supporting evidence. Not only are sperm counts going down, so is testosterone, and these are obviously related. Next up, rates of testicular cancer are increasing. And surveys show that masculinity is decreasing. These all fit together, and it seems difficult to not posit a general common cause or set of causes. I would guess improved clothing and heating is a major player and the causal evidence for heat stress to sperm quality is strong. As in, they literally put monkeys in hot baths and checked their sperm quality.
https://kirkegaard.substack.com/p/secular-genetic-phenotype-paradoxes
Masculinity surveys, note these are pre-Woke takeover
https://today.yougov.com/topics/society/articles-reports/2016/05/23/decline-manly-man
I was interested in including something about this, but I found a few studies saying that sperm count didn't really correlate with testosterone. Obviously this isn't true at the extremes (if you have zero testosterone ever, I guess you are a woman and don't have sperm) but it seems to be true at the margins. I only looked into this superficially; let me know if you've investigated more and found I'm wrong.
I wrote up the various lines of evidence https://kirkegaard.substack.com/p/its-not-just-sperm-quality-decline
Surprised there was no mention (that I can see) of the world becoming more peaceful since WWII, especially in daily interactions, probably in part by the removal of high-testosterone men into prisons. (This presupposes that high testosterone is correlated with both higher sperm counts and higher violent tendencies, which quick research indicates that it is.) Norms have changed significantly over these 70 years, removing high-T guys into prisons, or self-segregating them into violent sports. The decline in everyday violence (eg bar fights) also creates an environment whose cues, to the extent they influence T production, are more relaxing, so whatever the environmental contribution to T is should have declined.
Obv this is a hypothesis (or two hypothesis with a link) and empirical studies are needed, but I hesitate to suggest any; the sheer number of countries/regions, over time, over norms, creates too many confounders for me.
It's not mentioned because it's an orthogonal hypothesis with only a tenuous relationship to what's being discussed. In short, it's not germane. I fail to see why you are surprised.
The hypothesis that we've removed the high-T men from the gene pool through policing might be wrong, but it isn't orthogonal.
The homicide rate in the US today is about the same as in 1945:
https://marginalrevolution.com/wp-content/uploads/2011/05/Violence-Stylized-2.png
I would advocate strongly for a "impact of plastics on the human body: much more than you wanted to know" post from our fearless leader.
seconded
Yeah it's one of things I'm super confused about. It both seems like a very underrated and overrated problem
What does "community-dwelling" mean in this context? Does it mean people who are not institutionalized (i.e. in long-term medical care or prison)?
What a hilarious timing, to publish it one day after the meta-analysis:
"Worldwide Temporal Trends in Penile Length: A Systematic Review and Meta-Analysis"
https://wjmh.org/DOIx.php?id=10.5534/wjmh.220203
(Spoiler: the analysis concludes that the erect penile length increased 24% over the past 29 years.)
Is that self-reported length or did some researcher have to stand there with a tape measure as the subject watched porn?
If it's self-reported, I think the ubiquity of porn where (I assume) the male actors are well-endowed, and assumptions that "the average size is supposed to be X so I better say I'm at least X", might be at work there.
They excluded all studies with self-reported measurements.
So somebody *did* have to stand there with a tape measure. Dedication to science! 😂
I think you have to use a ruler rather than a tape measure if you want reliable results. Otherwise it's not clear where the baseline is. (not accounting for this fact apparently casts a lot of doubt on the 24% figure)
Also they sometimes get it up by injecting vasodilators rather than more artisanal methods.
source: doi:10.1038/s41443-017-0013-3
How many of these potential causes point to continued decline? E.g. it seems like plastics and pesticides have more or less reached market saturation at this point -- will we really see significant further increases in exposure to them going forwards?
I agree with this, but remember that Levine et al say the decline has intensified in the past 20 years; I would have thought we were at saturation for those things 20 years ago. Maybe there are other developing countries where we hadn't, and the intensification is concentrated there?
Or maybe we're measuring the sperm counts of people who got a lot of plastics/pesticide exposure when they were babies? Basically the numbers appear to be increasing because people who grew up with less exposure are dying?
The possibility I'm most worried about is epigenetic changes that get passed from father to son.
"It feels wrong to me to model this linearly, although I can’t explain exactly why besides “it means sperm will reach precisely 0 in thirty years, which is surely false”"
It seems to me that biology generally isn't linear. There are s-curves, there are sudden breaks, and there's random things having an effect.
As for vitamin D, there's more to sunlight. Humans have nitric oxide precursors under the skin that are activated by sunlight. It definitely affects blood pressure, it might affect sperm production.
Speaking to the plastics issue -- seems important to note that at least for the map shown it's measuring plastic waste *emitted to the ocean* per capita.
I've lived for extended periods in both the USA and South America, and it has always felt like if anything I had less contact with plastics in South America than in the USA, but that the disposal of plastic waste in South America was less effective.
It's common to see lots of trash on streets, beaches, etc to an extent that I don't really see in the USA -- I would suggest that it's possible that we have more contact with plastics in the USA but they are disposed of in such a way that less of it ends up in the ocean.
Admittedly i have no data to support this apart from my own observation and vibes
My understanding is that countries that emit more plastic in the oceans do so because of poor waste management infrastructure. If a truck comes around every week to haul off trash, people will use that service. Absent waste disposal options, people have no choice but to find another outlet to keep the garbage from piling up, and the river runs 24/7.
That may still translate to higher environmental exposure, from waste upstream, especially if population centers tend to be on the rivers. However you'd also expect that to translate into lower animal sperm counts, but maybe that's confounded by selective breeding.
That makes sense. At least in my experience there were plenty of waste disposal services, the issue I think was more of a combination of more stray animals getting into the trash and scattering it and less taboo on littering. Would not be the case possibly in other less developed south American countries though. Unless you're getting your water directly from the river though -- which I never heard of happening (city water did come from the river, but with plants in the mountains before the river ran through any population centers and therefore with little plastic) -- I can't see this having a bigger effect than everyday contact in the USA would. This obviously would be different in other countries though; would be interesting to see a comparison of some sort within latam
Yeah, it would be great to see a comparison story of phthalates and other plastics of concern in communal areas (river, playground) across countries.
Were there smaller communities upstream that had fewer government services? (trash, water, electric, free wifi on mass transit vehicles)
Not really -- a couple close to the capital, but it was mostly just mountains
Admittedly not a situation that would apply in other countries
I mean it's very possible that a strong correlation exists between societies that can't collect garbage effectively and societies that can't keep it out of their drinking water effectively.
If you are familiar with the curve of population against time in a fixed-resource culture, say, bacterial colonies in a petri dish, you will be familiar with the exponential growth, slowing down as resources dwindle and waste-products accumulate, eventually leading to a slight reduction in population then a catastrophic crash. Well, what would that look like if we consider ourselves in the situation of those bacteria? We know that over-crowding and stress cause a rise in non-functional behaviours (self-injury, homosexuality - no offense to gay people who were always that way!, paraphilias, aggressive behaviours etc) in both animal populations (eg pigs in a factory farm) or humans in an artificial environment such as a crowded prison. Stressful overcrowding is, I'm sure I have been taught somewhere, a cause of low sperm counts (unless, oddly, you are overcrowded among men alone, in which case elevated testosterone accounts for rises in aggression and sperm counts).
Seen in that light, perhaps some of the odd behaviours we see, especially those that prevent reproduction - asexuality, transgenderism, homosexuality, bizarre genders - might fit in with where we are on that curve. Likewise, we delay having children and have fewer of them as economic conditions get harsher. Now we can add a falling sperm count to the list of physiological ways we unconsciously try to stave off the collapse. We may be at the stage of population contraction and perhaps these are parts of the mechanism.
Economic conditions aren't getting harsher though.
For people who want to learn more about sperm biology, I wrote this post last year: https://denovo.substack.com/p/know-your-sperm
I don't think fertility will actually decrease due to declining sperm count.
I've observed a number of morphological differences between the older generations and modern generations; modern generations have smaller and more delicate hands, for example, as a result of the fact that we're (collectively, on average) not smashing and vibrating the shit out of ours hands on a regular basis as much.
Even if sperm count is decreasing, it isn't obvious to me that this necessarily represents a decrease from a "correct" number of sperm. It could simply be that people are less exposed to environmental conditions that were previously increasing the number of sperm.
For example, as I understand it, selenium, which may increase sperm count, used to be a major pollutant in our waterways, but we've greatly improved our treatment of wastewater to eliminate this pollutant - and over the past couple of decades, selenium deficiencies have started to become more prominent an issue; perhaps the odd thing isn't modern sperm levels, but the sperm levels we are attempting to make a comparison to. Mind, it's hard to find exact details, so don't take this as advocacy of this idea, but merely using it as an example of something else that might be confounding our data - we don't know what the "correct" value should be, and things can increase as well as decrease sperm count, so it's entirely possible that the issue is a -decrease- in key pollutants.
This is a good point, and I hope future studies manage (thought surely there are cultural barriers) to measure counts from pastoral and hunter-gatherer groups with very limited contact with the pollutants of today and the early 20th century.
An anecdote point: in 1979 (solid date, it was summer after my freshman year in college), I recall an industrial chemist friend of my dad's remarking, "that new-car smell, that's plasticizers, phthalates [he used the word], out-gassing. They're everywhere, if we ever find out they're bad for us, that'll be a big problem".
So, 1979, an industrial chemist in the aerospace industry believed that they were already everywhere, and worried-but-did-not-know if they were bad for us. And also, there may be a difference between "new" (flexible, new-car-smell) plastic and "old" (brittle) plastic in the amount/rate of plasticizers that they leak into the environment.
they are bad for us, most are carcinogens.
Everything is a carcinogen.
I'm surprised you seem so skeptical of the obesity explanation. We know obesity rates are going up, and that obesity is associated with reduced sperm counts, so wouldn't it be pretty surprising if rising obesity weren't causing at least some of the decrease? (even if obesity being the only cause doesn't perfectly match the noisy regional variation).
It makes me wonder if there might be some cognitive bias in play, favoring exciting solutions (e.g. toxic environmental plastics are endangering us!) over mundane solutions (e.g. obesity is already known to be associated with reduced sperm counts).
> We know obesity rates are going up, and that obesity is associated with reduced sperm counts, so wouldn't it be pretty surprising if rising obesity weren't causing at least some of the decrease?
It wouldn't be surprising if both obesity and reduced sperm counts are caused by the same thing. For example, testosterone levels. It's a classic case of "correlation is not causation".
Here is a randomized study suggesting that the effects of excess weight on sperm count are causal. Also, Scott didn't offer evidence against such a causal connection, and in fact his own link and wording on obesity/diet assumed a causal relationship w/ sperm count, even if he doubted its role in the long term trend. (note diet could be a "shared" cause here, but that is hard to separate from obesity and Scott just lumped them in the same category - diet and obesity).
https://academic.oup.com/humrep/article/37/7/1414/6587152
At the moment (2/17/2023, 10:22 EST) substack is saying this was posted "11 hr ago", but I thought I saw it (days?) earlier. Is there a glitch in the reported time for posts?
There was a subscribers-only "sneak peek" posted a while ago.
Ah, that explains it. Many Thanks!
There is at least one dissertation / thesis. prior to 1975 that penis size is decreasing as well, and the proposed cause was pesticides. The author was my favorite Aunt although she left KS abruptly after marrying my uncle. I was told she returned to southern CA. Her name was Joanne (SP?) Gaston or Joanne Gaston-Pressgrove. I have been unable to find her and would ask that if someone is able to find her thesis or any indication of a Berkly grad with a similar name, I would appreciate you sharing any information. Unk passed a few years back and I would really like to let her know. TIA
Actually, the largest contributor - assuming the fall is real - is probably just age.
Look at the sperm count by age decile and compare vs. the average age of the "donors". Increasing life expectancies = older men = older men contributing sperm count numbers.
I am 99% sure sperm counts decline with age, period, and an aging population would certainly yield lower overall sperm counts just because of the aging.
The other things are probably much more minor factors, relatively speaking, but are far more alarmist hence useful to dumbass narratives. See climate change.
Everyone realizes this and has controlled for it.
Approximately a perfect reply. And close to providing an acronym (Ertahcfi or Ertacfi) for future use.
While your at it, can we do the declining testosterone levels claim as well? Interesting post!
What about exercise?
"Harvard Gender Science Laboratory paper [...] mostly just says that it sounds sexist to say something bad might be happening to men (it also adds that since some studies have found the decline is higher in Europe, it’s racist for saying something bad is happening to white men)."
I read some of the paper, and the closest I could find to a claim of sexism was a paragraph mentioning that MRAs and Alex Jones have referenced declining sperm counts to complain about soy boys. The main point seems to be that even if sperm counts have declined, it doesn't seem to be pathological, there's no reason to think the levels in the 70s were natural or optimal, and high sperm count is not particularly a marker of general health.
It does use a lot of disapproving air quotes about dividing countries into """Western""" and """Other""" and points out that pollution of plastics and pesticides tends to be worse in poor countries, which doesn't really fit with declining sperm counts in western countries.
Aside from that paragraph, there's the one saying "Narratives about the decline of men have been taken up by white supremacist and misogynist groups who claim that men in the Global North are
victims of their liberal feminist environments", the one saying "The results have been framed in terms of a crisis for Western men and masculinity", the one saying "representations of sperm are ‘deeply contextually situated within a crisis of masculinities’", etc. See also https://news.harvard.edu/gazette/story/2021/05/fears-over-falling-human-sperm-count-may-be-overblown/
The "how do we know the levels in the 70s were optimal"? question seems like concern-trolling - there are many pollutants and illnesses that we know lower sperm count, very few that raise it, and we should have a prior that we're getting further away from the EEA over time. It also seems naturally concerning that there's a level at which people stop being fertile, and we're approaching it apparently linearly. While it's always possible to have a galaxy-brained take where sperm count seesaws in a U shape forever for unclear reasons and everything will be fine, I think it's fair to not have that as your base model, and when someone starts suggesting it should be I start looking for ulterior motives.
It's a fair point that most pollutants would lower sperm count, not raise it (Thegnskald above mentions selenium as a counterexample, although most of the studies seem to link it to motility rather than total count).
Still, if our main concern is that maybe "whatever issue causes declining sperm causes other bad things too" then it seems like we should be looking for evidence of that correlation, not just imagining it. On the other hand, if our main concern is that a large fraction of men will be unable to have children, shouldn't we already be able to see an increase in problems at the low end of the bell curve?
Disclaimer: N=1, personal experience, YMMV.
I tried to have children with my (now ex-) wife for ±5 years using IVF in France. The cause of infertility was my sperm count being too low (as low as <1m/mL at the worst.) Since I spent plenty of time around doctors and other patients, here are a few points I thought I could share:
- There is a global concensus among professional that the global sperm count is lowering worldwide (they might be biaised since they only see infertile patients though)
- My sperm count varied dramatically (20× factor) over a period of 5 years. Some can be attributed to the surgeries I had, but in between surgeries, I still experienced a 5× change. It didn't seem corelated with any other variable (health, eating habit, alcool consumption or smoking)
- Sperm count is usually corelated with sperm quality. So sperm count and fertility don't have a linear relationship, and it might skew some studies quite a lot:
- Low quality sperm can be very short-lived and when the lab performs a sperm count, they only count the effective sperm found (discarding dead, or imobile ones), making the timing between production and analysis very crucial which it is not.
I made a few samples at home and brought them to the lab for analysis about 30" later. I didn't check at what time they made the count, but I had 30% less than the week before. I paid a little extra for a more in-depth analysis and went to a different lab where I needed to produce the sample there, and they would check periodically over a period of 24h.
Just after producing I had my 30% more, and ~80% were dead (thus not counted) after 24h. The high variability of the result might just be the different collection methods used.
Look I realize a lot of people are putting effort and thought into this hypothesis.
But frankly, I find it crazy to see an idea entirely based upon surveys of non-random, non-representative samples of the population being so widely discussed as though it has solid scientific backing. The media really need to chill on this topic.
These meta analyses are mostly GIGO. The fact that this obvious problem with the data is only listed as limitation #3, and then is so easily dismissed by the authors of these studies, is something of a cosmic joke.
Scott your analysis of the issue was legitimate and helpful to frame the topic.
But you forgot to mention what I see as the most likely possibility: Based upon my observations of other fields of epidemiology that receive far more funding and research interest, I estimate a 90% probability that in 20 years we still will not have any truly useful data to either strongly support or falsify this hypothesis.
Likely instead this will continue to be among the topics to be debated endlessly among friends at a pub while enjoying a flight of good beers…
In 20 years it should reach the point where fertility goes way down; if nobody has noticed this by then, it's been (at least partly) disproven.
(or it's sublinear, I guess)
But I don't think we're comparing like with like; if you compare today with twenty years ago, fertility has gone way down. Is that due to declining sperm count or to people avoiding childbearing, not wanting more than one or two kids, and the rest of the question we argue over when we discuss replacement rates?
If the baseline remained the same over a hundred years (i.e. no contraception or abortion, no limiting family size to 'just two will do', and people want to have babies as soon as they're married, people get married in their early twenties), then you could compare 'how many kids did grampa father to how many kids did grandson father' and see if fertility was affected by decline in sperm quality. But since we don't have that kind of steady underpinning, we can't see if "are we at the point when fertility goes way down due to declining sperm", not even in developing countries because there have been huge campaigns to reduce population numbers there, from giving women access to contraception to paying poor men to have vasectomies (and of course things like China's One Child policy):
https://timesofindia.indiatimes.com/city/indore/50-more-incentives-for-male-vasectomy-across-state/articleshow/89613490.cms
"In all districts of state, male undergoing vasectomy will get Rs 3000 as incentive money instead of Rs 2000 paid earlier. Similarly, females will get Rs 3000 for post-delivery tubectomy and Rs 2000 for post abortion sterilisation under revised incentives, showed records."
https://qz.com/india/1414774/the-legacy-of-indias-quest-to-sterilise-millions-of-men
"In 1976, men across India were drastically changing their behaviour. Some were abandoning the beds inside their homes to sleep in fields; others were skipping major festivals and public gatherings. Those who in the past had taken the train freely, without a ticket, were finding alternative routes. They were all trying to avoid government officials. On trains, inspectors were suddenly cracking down on ticketless passengers with heavy fines, but they would give fare dodgers a break on one condition: that they agreed to be sterilised.
Government workers, from train inspectors up to the top brass, were working to sterilise as many men as possible. Some even had monthly quotas for how many men they had to convince to get vasectomies. In turn, poor men in rural villages were doing everything they could to avoid government officials, because any such encounter might end with the villager on a dingy operating table where his genitals would be cut—whether or not he wanted the operation, whether or not he already had children."
Without knowledge of such campaigns, attributing "wow, sudden drop in fertility rates in India during the late 70s" to "declining sperm count/quality" would be mistaken.
I'm apparently the top "NO" holder on Manifold, so I suppose I should say something.
My estimate (based solely on this post, and no other research) is about 30% for "In twenty years, will the best evidence available suggest that sperm counts have been substantially declining across most of the world?" That's, roughly, 25% that there is a non-trivial phenomenon (beyond simply "people are getting older", which Scott said doesn't count), and 5% "there is no decline, but the scientific establishment in 20 years is fundamentally broken, probably because of scientists who do bad research to get headlines and/or tenure".
The key is Figure 2, along with "approximately every study makes a ton of compromises for longitudinal data". As other people have mentioned, Garbage In Garbage Out. And "sperm production of a healthy male" (by height? by weight? by mL of seminal fluid?) ... well, maybe it does vary by 50% depending on the population, depending on what metric you are using. Which just means the differences in populations surveyed (which Scott notes) make a simple linear regression problematic.
( there is also my meta-heuristic of "after years of reading this blog, I believe Scott consistently over-estimates the likelihood of phenomena like this being real" )
With any luck.
Somehow people are still arguing over what causes obesity after 40 years. So I’m not holding my breath.
Please also look at testosterone changes over time, it would make sense that this is a causal driver of sperm count.
The proper level of concern should be... I was going to argue zero, but then I found actual data. But the numbers are all over the place in a hard to disentangle way. Seriously, look at this analysis, and tell me the numbers thrown about aren't sometimes contradicting each other, or at the very least difficult to reconcile. Eyeballing it, it seems 2% - 7% of men have defective sperm problems. Of the 200 hundred pronatalist married couples I know, I would say 4 - 7 percent have difficulty conceiving. Maybe half of that is due to male sperm issues. So these percentages strike me as a bit high. Nonetheless, if the percentage were to double, I would start to be very concerned.
If we combine increased male issues with women trying to conceive later in life, we could wind up with a lot of disappointed couples, unable to conceive. Only 12% of the population has a 4 person household. Dropping that percent any lower seems pretty bad for creating a culture where people would want children.
So, while I, started out writing this skeptical that this matters... I am now actually worried about this on some margin. Though, I still think improving sperm count is at best a third tier problem for improving fertility. There are more important levers to pull on that front.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4691969/
"Of the 200 hundred pronatalist married couples I know, I would say 4 - 7 percent have difficulty conceiving."
I do think that if you're spent years on artificial hormonal contraception telling your body "no pregnant!", then when you do want to have a baby, it's hard to turn that oil tanker around. But this is just my own view.
As to sperm count/sperm quality, that's a whole other question and I agree that the studies seem to be all over the place - it's declining, it's not declining, it's worse in developed countries, it's worse in poor countries, pick your own sample.
"Given how hard it is to find this effect at all, we should be suspicious that all of these differences are fake, and that actually we don’t know anything about where sperm decline is faster or slower."
I don't understand. From the examples you've given, isn't it obvious that poorer, less privileged people have lower sperm counts than richer, more privileged people?
Anyone know what's up with Data Secrets Lox?
Funny. I came here 1 minute after you to ask the same question.
https://www.datasecretslox.com/index.php/topic,8778.0.html
Major confounder not discussed- underwear style. It's already known that men who wear cotton boxers have higher sperm counts, and men who wear tighter fitting underwear have lower sperm counts. I recall a few studies saying that men who wear underwear made with more synthetic materials have lower sperm counts, as well, so if that's true(I have only seen twitter screenshots of the conclusions but polyester on your balls reducing fertility seems at least reasonable, if not confirmed) then we have two confounds(change in material used in underwear and change in style of underwear). Even assuming only underwear tightness matters, men- or at least those men who participate in fertility studies- switching from boxers to athletic underwear or boxer briefs would represent a major confound if it happened.
So did any of these studies control for or even document what kind of underwear their participants wore?
I think you're being arbitrarily dismissive of the Harvard paper or their authors.
"mostly written by Gender Studies professors, anthropologists"
Lots of studies in the past have included various biases, for example they made wide claims while only including white men in their data. Of course you don't need to be a gender studies professor to realize this is bad science.
Good science is difficult and anybody has the ability it do it correctly, and it's not meant to be socially or politically motivated. But I think they could be more attuned to these identifying these biases and calling them out.
All studies today include many biases. Are you using only undergrads as your sample population? That's a far bigger bias than using white men from around the country.
Gender Studies professors have an agenda. If the data doesn't accord with their agenda, it's the data that has to go, never the agenda. I know that every scientist has a political opinion and that a true "view from nowhere" doesn't exist, but the more invested someone is in their ideology, the less trustworthy their science. I don't agree with completely dismissing science done by an ideologue, but it's perfectly logical to be very skeptical.
Gender studies professors generally aren’t scientists they are activists. They also generally aren’t very bright.
Methodology should be considered. In the earlier studies, the counts would’ve been done with a calibrated micrometer - just a person at a microscope clicking a counter for each sperm in a little grid. Not super accurate. More recently, I believe there’s image analysis that can count it for you or at least it does some of the heavy lifting. I’m sure this is described in materials and methods of the papers.
Apologies if this has already been discussed - it was seemin’ like something that would come up.
What if the sperm count correlates with the social status of the male? It is a heretic thought, but primate reproduction tends to rely on high status males... The sperm count decline might be a consequence of the patriarchy being smashed progressively.
A possible solution? I was directed to this by the good people over at r/Drama:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9867816/
"In conclusion, drinking Coca-Cola and Pepsi-Cola could promote testis development, enhance testosterone secretion, increase serum EGF concentrations, also accelerated expressions of AR protein in the mice testes. Our findings provided the scientific bases and for fully understanding CBs effects and their mechanism on development and reproduction functions of humans, but also benefit to prevent prostate dysfunction and cancer."
Good for male mice, bad for female mice and their reproductive system, though.
I’m curious about evolution. In the past people would have a dozen kids in the hopes that a couple of them would live to procreate, a high sperm count would presumably make conception easier so women would get pregnant faster and have more kids over their lifetime. Now most people only have a couple kids who will almost certainly have a couple kids of their own, and it doesn’t matter if it took and extra year or two for the parents to conceive. The removal of this evolutionary pressure forcing sperm counts up could mean that random mutations which bring it down are no longer being selected against, but there is still some amount of pressure for general fertility which is why the decline is fairly small.
You should do a "Testosterone MMTYWTK"
Because the data is contradictory, it's useless. You can't make any useful predictions based on garbage info. This is some sort of astrology tier guesswork.
My guess is that it's due to stress. Richer people are less stressed out, so have had a smaller decline.
Drinking water is being delivered by PVC pipes now more than ever. About half the distribution size water pipe in the USA is now PVC. I believe it's the reason for our increase in pancreatic cancer, diabetes, and more. There are dangers in exposure to PVC. Water utilities should not use PVC but should use the time-proven safety of iron pipe.
Manifold is very useless for markets that expire in more than ~2 years. There is just no way to make mana on them when you consider the opportunity cost.