The Sperm Count Culture War

(Quillette) Attempts to make science conform to ideology have enjoyed a long and dispiriting history. For many centuries, religion was the main perpetrator, and scientists and philosophers who ran afoul of the Church and the Inquisition were burned at the stake or left to rot in prison. In the early 17th century, the astronomer Galileo was convicted of heresy by the Roman Catholic Church for daring to suggest that the Earth revolved around the Sun. His book containing the evidence he had amassed was banned and he was sentenced to prison, and then spent the last nine years of his life under house arrest.

In the 1930s, under the banner of “scientific socialism,” the Soviet Politburo imposed the pseudoscientific theories of Trofim Lysenko. Lysenko rejected modern genetics in favor of crackpot ideas that promised to usher in a Soviet utopia. Scientists and farmers who dissented were persecuted and ended up dying in labor camps. As a result, Soviet agriculture was set back for decades, leading to millions of deaths and food shortages.

The lesson: Just because a religious body issues a decree or an autocratic regime redefines science, it doesn’t change reality. Ignoring science in favor of a preferred outlook on the world (however well intended) can have devastating consequences. Since we live in a free society, rather than under a theocratic regime or a totalitarian Stalinist state, we consider ourselves to be modern, which, above all, connotes enlightened. However, in recent decades we have had to contend with more subtle influences on free inquiry—those associated with the culture wars.

Hotly debated issues such as climate change, biotechnology/genetic engineering (GMOs), carcinogens in our food and the environment, 5G wireless communications, vaccines, stem cell research, abortion, and nuclear power show that conformity with a powerful political or religious position can impede a nuanced discussion of complex, highly technical questions. Although no longer wielded principally by a powerful religious body or the state, present-day forms of ideological influence are more subtle, varied, and pervasive in contemporary societies, and, therefore, more difficult to hold up for critical evaluation.

Let’s examine a recent textbook example of an egregious ideological interpretation of a serious scientific issue.

Sperm count crisis or controversy?

In May, a group of feminist academics from Harvard and the Massachusetts Institute of Technology waded into the longstanding controversy over declining sperm counts and what, if anything, this phenomenon portends for the future of humanity. Evidence of declining male fertility first emerged in studies dating to the 1970s. The decline was found to be particularly acute in the most industrialized West, North America and Europe. This finding touched off a debate that has raged in recent decades over its causes and consequences.

Declining sperm count is more than just a medical issue; falling male sperm concentrations could have profound societal impacts by reducing fertility rates. If the observed trends are accurate, addressing the causes is critical. But determining those causes requires a level of scientific dispassion that is disappearing from some social-science-focused research centers, as ideology has crept into science. (I have addressed the background issues surrounding the evidence of declining sperm counts and their possible implications here).

The latest entry in the sperm count debate comes from a Harvard-MIT research team led by philosophy professors Marion Boulicault and Sarah Richardson. They recently published a paper in the journal Human Fertility entitled “The Future of Sperm Variability for Understanding Global Sperm Count Trends.” They also published an article in Slate summarizing their findings for a lay audienceWhile the scientific paper is dense and difficult to navigate, the Slate article gets straight to the point with its title: “The Doomsday Sperm Theory Embraced by the Far Right.” Its subheading elaborates: “The idea that male fertility is on the decline is an old myth dressed up as science.”

The authors tell us why they believe the accepted science on declining sperm counts should be rejected:

The human species is in grave reproductive danger, according to recent headlines. Some scientists say that sperm counts in men around the world have been plummeting, with Western men approaching total infertility by 2045. Far-right “Great Replacement” theorists, who fear that people of color are “replacing” the white population, have taken up the research with gusto.


The narrative that white, Western men are in danger of emasculation and disappearance has deep roots in white nationalist discourse. It is tied to a nostalgic cultural myth of a past in which white men held unchallenged power.

Conflating science with ideology

The authors all but ignore the science to focus on what they believe is more important—the ideological framing of the issue in socio-cultural discourse. Their article is a response to what is widely considered to be the most definitive research on science of sperm count decline, a 2017 meta-analysis of worldwide sperm count trends by Hagai Levine, Shanna Swan, and colleagues. The study, which reviewed more than 50 years of research, documented evidence of declining sperm counts in different countries.

The authors analyzed 244 estimates between 1973 and 2011 grouped into “Western” countries (US, Canada, Europe, Australia, and New Zealand) and “Other/non-Western” countries (including Asia, Africa, and South America). They found that total sperm count had declined by more than 52 percent among Western men between 1973 and 2011, whereas no significant decline was seen in “Other” countries.

It’s that conclusion, now widely embraced by the mainstream science community, that has provoked Boulicault and colleagues’ ire. They offer two major objections. First, they argue that the observed decline in Western countries may simply be due to normal variation in sperm count and has no implications for male health or fertility. Second, they object to Levine’s grouping of the available studies into “Western” and “Other.” The first objection has to do with science, which the data should be able address. The second is largely ideological, a perspective spurred by the escalating culture wars.

Before deconstructing their argument, it’s helpful to understand the political and ideological prism through which the Harvard-MIT team views this issue in particular, and science in general. Neither Boulicault nor Richardson is a scientist. Both are philosophers, who openly proclaim their fealty to feminist scholarship—the focus of the GenderSci Lab, a cooperative started by Richardson in 2018.

GSL focuses its scholarship on “the intersectional study of gender in the biomedical and allied sciences” and “specializes in analyzing bias and hype in the sciences of sex, gender, and reproduction and in the intersectional study of race, gender, and science.” It is enlightening to read a post on its site by several of the paper’s authors, in which they further lay out their case, calling the Sperm Count Decline hypothesis “a new manifestation of a familiarly pernicious theme”:

Sperm decline claims invoke powerful rhetorics and narratives around gender, sex, race, ethnicity, and anxieties about our future. Of particular concern is the uptake of this work by overtly white supremacist and misogynistic groups. These groups have used Levine and Swan’s research to argue that the fertility and health of men in whiter “Western” nations are in imminent danger, often linking the danger to the perceived increase in ethnic and racial diversity and to the influence of feminist and anti-racist social movements.

What these anxieties have in common with the threat of sperm count decline is the premise that, in an environmentally clean and appropriately-gendered social past, there existed an optimal and natural manifestation of masculinity.

In their Slate article, they give a more detailed explanation of how these “powerful rhetorics and narratives” have shaped the discourse regarding declining sperm count:

How did these unscientific categories and assumptions make it into the research in the first place? The narrative that white, Western men are in danger of emasculation and disappearance has deep roots in white nationalist discourse. It is tied to a nostalgic cultural myth of a past in which white men held unchallenged power.

It is all too easy for scientific institutions, with majority-white researchers, to center white people and further these myths, which circulate often unconsciously. … The recent sperm count decline research demonstrates how racist, sexist, and Eurocentric ideas can get embedded in the categories that scientists use to analyze data.

Dissecting the science and ideology

Boulicault et al. propose an alternative hypothesis, not for its intrinsic scientific merit, but because they recoil at the effects on the public discourse unleashed by the scientific findings in the Levine review of a half-century of data. In opposition to what they see as the implicitly racist and Eurocentric view of what they say is Levine’s “sperm count decline hypothesis,” they offer their alternative perspective, which they call the “sperm count biovariability hypothesis.”

Source: Boulicault et al. 2021

To the extent that they frame their own hypothesis as an alternative to Levine’s, they are making a mistake because their central claim that low sperm counts have no implications for reduced fertility is simply wrong. Their second mistake is to restrict their attention to the offending Levine meta-analysis, which itself addresses just one narrow question. By doing so, they fail to consider a number of crucial phenomena.

Compared to other animals, humans have poor fertility. That is, the chances of a male impregnating a female are much lower. In humans, sperm count is determined by two factors: the number of Sertoli cells in the testes, which is largely determined in perinatal life, and the frequency of ejaculation, which is variable. Unlike in other animals, there is no storage of sperm. Sperm counts can vary by as much as two orders of magnitude between individual men, and in most cases, nothing can be done to increase a low sperm count.

Does sperm count matter?

It is incorrect that a low sperm count has no implications for fertility. Above a certain level—40 million/ml—there is no further improvement in fertility. However, when it comes to the lower range, there is a big difference between having a sperm count above 20 million/ml and having one below this level. In the former case, the chances of fathering a pregnancy are 65 percent—in the latter case 36 percent. As Richard Sharpe, a reproductive expert in the UK’s Medical Research Council Human Reproductive Science Unit in Edinburgh, Scotland, has concluded, “[H]aving a low sperm count makes you less fertile, although it does not exclude the possibility that you will impregnate your partner over a span of time.”

In addition, Boulicault et al. barely mention that low sperm count is associated with reduced sperm quality. Nor do they mention that only a minority of human sperm (five to 15 percent) are morphologically normal even in fertile men, in contrast to the situation in animals, where 90 percent or more of sperm are normal. This difference between human male fertility and that of other animals has profound implications.

They also fail to note that reduced sperm count is associated with higher mortality: the lower your sperm count, the greater your chances of dying. Sperm count is associated with other reproductive pathologies in males, including testicular dysgenesis syndrome, cryptorchidism, hypospadias, and testicular germ cell cancer. There is solid evidence that rates of testicular germ cell cancer have been increasing in recent decades, and it is a disease predominantly of young men in the prime of their life. And they fail to contextualize the issue. In advanced industrial countries, as in Europe, where fertility is declining and fecundity is below the replacement level, and where women tend to have children at an older age, the fertility of couples is further reduced when the male has the added burden of a low sperm count.

Although most evident in European countries and Japan, a trend toward an aging population, smaller family size, and a shrinking work force is discernible wherever prosperity is increasing. These trends will have profound effects on society’s economic base and the allocation of resources. The Chinese government’s recent decision to allow families to have three children—a further unwinding of its “one-child policy”—is a response to these trends. For people who are concerned about the impact of biology on society, it is curious that the authors ignore this salient phenomenon.

Boulicault et al. rightly question the hype about “endocrine-disrupting chemicals” as a favored hypothesis to explain declining sperm counts, but they neglect to mention recent, high-quality work that suggests exposures early in life may affect reproductive health. Specifically, in utero exposure of the fetus to pharmaceutical products taken by the mother deserves careful study. In addition, a study examining cases of cryptorchidism requiring surgical correction in France over a 13-year period revealed 24 hotspots, suggesting that fetal exposure to industrial pollutants, including metals, coupled with socioeconomic deprivation could be contributing to this condition.

From botched science to ideology

Although Boulicault et al. charge Levine with being a prisoner of “culturally-determined categories,” they are so caught up in their own ideological narrative that they feel no obligation to check it against the empirical data. The result is dismaying. A telling error is their strenuous objection to the grouping of populations into “Western” and “other/non-Western,” which they seem to think is evidence of some kind of Eurocentric intellectual imperialist bias. But this decision was simply motivated by the relative dearth of studies from other parts of the world.

Their programmatic approach is further illustrated by a hyper-focus on the societal impact of the “falling sperm counts narrative” and the anxieties it has provoked, particularly among men’s rights activist groups on the political Right, who are responding to what they see as a crisis of masculinity. The problem is that the authors start from a set of sociological and political concerns regarding women’s roles, healthcare, colonialism, and racism, while not bothering to delve into the science regarding human fertility. Rather than being interested in learning and integrating the best information relating to the question, they frame it as a culture war issue.

Expertise does matter. None of the seven authors on the paper has published on male reproductive pathology. And while they indicate that they received input from andrologists, none is named. These consultations clearly did nothing to correct the inadequate picture the authors paint of male fertility, and many of the papers they cite reach conclusions at odds with their claims. This raises a serious question about how the paper could have passed peer review.