Where have all the French sperm gone? What will life be like in "a world without Frenchmen?" Such are the weighty questioned asked by newspapers everywhere after reading (a press release about) a new study by French researchers that suggests that French males have seen declines in the sperm concentration of their semen. But before the misguided French jokes come out and we all start worrying about the End of Sperm, let's take a deeper look at this study, which builds on a mountain of sperm count research.The study, headed by environmental health epidemiologist Joëlle Le Moal and published in Human Reproduction (abstract, pdf of full text), looked at around 26,000 "of totally infertile women undergoing an assisted reproductive technology (ART) procedures in the whole of France over a 17-year period." The source population was around 155,000 men aged 18-70, who were partners of women also undergoing their first ART procedure and whose semen samples were available.According to the authors, the results show that those men saw their sperm counts decline by 1.9% per year, while the morphology (roughly, quality) of their sperm also declined, although they saw no decline in average motility. Or, in other words, men whose partners had their tubes tied or blocked saw their sperm counts decline, while men who were actively trying to conceive (their partners were undergoing ART treatments, after all) did not. The upshot is this: the team found that average sperm counts declined from 73.6 million to 49.9 million per milliliter during the period from 1989-2005.So, are we in for a spermpocalypse? In their conclusion, the authors suggest as much:These results indicate a severe and generalized decrease in semen quality in France, possibly since the 1970s, which constitutes a serious public health warning.Besides fertility outcomes, semen quality is a sentinel indicator of gamete deterioration and thus should be considered as a biomarker of the resulting development outcomes (Joffe, 2010). This issue could be a growing cause of concern for the next generation’s health. Furthermore, semen quality was surprisingly correlated to life expectancy in a recent report (Jensen et al., 2009). All these aspects strengthen the need to implement gamete quality monitoring systems, for which infertility clinic data and the specific methods we employed might be considered valuable tools.They do have a point: Sperm are one half of our most basic building blocks, and if they're seeing widespread decline, then we ought to worry about it. But, as the authors note, there's a long history of sperm count studies out there, and many of them conflict with each other.Elisabeth Carlsen and colleagues published a landmark paper in 1992 that reviewed data sets from 61 papers published between 1938 and 1991. They found that between 1940 and 1990, male sperm counts had nearly halved, which the authors said suggested a worldwide decline.That is, a decline according to their data sets. There are a number of issues with comparing data from sperm count studies across such a large geographic and temporal range. First up is finding the subjects in the first place. If we're talking about average sperm counts of average men worldwide, you can't include men with fertility problems. But have you, average reader, ever had your sperm count checked? Probably not, unless you've had trouble conceiving. Why would you? As such, it's hard to find study subjects who are down to ejactulate into a cup, but it's a lot easier when those men are already doing so to assess their own fertility problems.Secondly, methods for sperm count assessment have changed. Sperm counters obviously can't be counting each individual sperm of the tens of millions in each milliliter of semen. They have controlled methods for counting a small sample, then multiplying, but those methods have changed, and the multiplication factor can produce huge differences in the final counts. As Claudia Hammond noted in an excellent sperm count study explainer for the BBC:The World Health Organisation (WHO) recommends using laboratory techniques that do not rely on an individual making a judgement, but this wasn’t the case for the earlier studies, making it hard to compare them with measurements taken 50 years later. And it is not just the practical techniques that have changed; statistical methods of analysing data have evolved too.When you look at the set of studies reviewed in the paper in more detail, it seems that although sperm counts do appear to have dropped in some places, they might have risen in others, even in different regions of the same country. In Paris, sperm counts appear to have declined, while they remained stable in another French city, Toulouse.Carlsen and team set the stage for worries about worldwide sperm count decline in recent history, as well as skepticism towards sperm count studies in general. And to its credit, the newest paper avoids the inherent issues with Carlsen's look at disparate data sets, and the men selected in this study were only at fertility clinics because of their partners, which was a clever way of ducking the infertile male bias.The one issue the authors note is that they could not control for socioeconomic status, which can affect sperm count. (For one, people of lower socioeconomic status are more likely to smoke and be obese, which both lower sperm counts.) The authors argue that people undergoing ART procedures are likely to have a higher socioeconomic status than average, and thus suggest that the average population's sperm count is even lower.Ian Sample, writing for the Guardian, counters that Le Moal's numbers seem "extraordinarily high" to begin with. And, as some have noted, the sperm counts are still within a normal range, although that's missing the point that the authors saw a decline of nearly 32 percent in two decades."That's certainly within the normal range, but if you think about it, if there continues to be a decrease, we would expect that we'll get into that infertile range," Grace Centola, president of the Society for Male Reproduction and Urology in Alabama, told Reuters. The Reuters story also notes that recent country-specific studies in Israel, India, New Zealand, and Tunisia have all shown declines.So, if we step back a second, sperm counts are quite possibly declining. Counting methodology may account for some changes in the numbers, but if methodology was changed to be more precise, it's hard to imagine that more precision would skew numbers uniformly in one direction.More importantly, we're talking about a legitimately existential problem here. If sperm counts are really on the decline, we soon may be faced with a generation of men turned into naked mole rats, whose pathetic sperm can barely swim correctly. And sure, we have plenty of people on Earth, but not being able to create more will lead to people straight into the most dystopian scenario imaginable, as Children of Men so excellently portrayed. So while I wouldn't go around yelling about the Sperm Reckoning just yet, it is probably high time for us to looking into why widespread sperm decline might be happening.Follow Derek Mead on Twitter: @derektmead
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