Guest Essay by Kip Hansen — 22 November 2022
A little lighter-hearted news of the imminent demise of humankind. Asked about his most recent study of worldwide sperm counts, Hagai Levine an Israeli researcher, gave the press the statement in the red (for crisis) box. [ source ]
We will excuse Levine for not getting the cliché right – English is probably not his first language. He means that “low sperm counts” are the canary…. I think.
Back in 2017, Hagai Levine, and his team published a paper “Temporal trends in sperm count: a systematic review and meta-regression analysis”. The “Wider Implications” of its Abstract read:
“This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50–60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed.”
The Times of Israel includes the following statement in a 2017 article on this study:
“This definitive study shows, for the first time, that this decline is strong and continuing,” said Swan [professor in New York’s Icahn School’s Department of Environmental Medicine and Public Health and co-author]. The fact that the decline is seen in mainly in Western countries, strongly suggests that external factors like chemicals and lifestyle play “a causal role in this trend,” she said.
[WUWT had a piece on the 2017 study here.]
Levine re-did his study to capture data from the rest of the world and then meta-regression-analyzed it in his latest 2022 follow-up study: “Temporal trends in sperm count: a systematic review and meta-regression analysis of samples collected globally in the 20th and 21st centuries “
” WIDER IMPLICATIONS: This analysis is the first to report a decline in sperm count among unselected men from South/Central America–Asia–Africa, in contrast to our previous meta-analysis that was underpowered to examine those continents. Furthermore, data suggest that this world-wide decline is continuing in the 21st century at an accelerated pace. Research on the causes of this continuing decline and actions to prevent further disruption of male reproductive health are urgently needed.”
As always, the press uses the alarming quote in which Levine says, (repeating our quote from above):
“Our findings serve as a canary in a coal mine. We have a serious problem on our hands that, if not mitigated, could threaten humankind’s survival. We urgently call for global action to promote healthier environments for all species and reduce exposures and behaviors that threaten our reproductive health.” [ source]
Well, Dr. Swan’s guess that the cause must be “chemicals and lifestyle” in the Western countries didn’t play out…the same team found the same thing in the less-developed global south. The 2022 paper doesn’t lay any blame or propose causes but does call for “Research on the causes of this continuing decline and actions to prevent further disruption of male reproductive health are urgently needed.”
Let’s see the paper’s money graph:
You’ll notice that this graph is based on “meta-regression models” ….and Levine is happy that his new study confirms and reinforces the findings of the 2017 study.
But what about his predictions of the demise of mankind?
The first study, 2017, found declining sperm concentration (SC) and total sperm counts (TSC) in North America, Europe, Australia and New Zealand and the second, 2022, found the same for South/Central America, Asia, and Africa. It would be informative to look to see if this dire situation has been affecting human populations for the last 20 years or so:
I don’t see that any of the predicted adverse effects from sperm counts or total sperm counts on the burgeoning populations of any of the continents. Population growth trends appear rising even more rapidly up after 1955/1960 — and show no signs of slowing down – despite Levine’s findings of lower sperm count or concentration numbers.
And fertility rates?
Fertility rates come down as standards of living go up. In North America, we see the post-WWII baby boom and as time passes, by 1970-75, that rate has come down and stays fairly flat. Every continent slopes downward and by the turn of the century, every continental fertility rate, with the exception of Africa, and the global fertility rate has settled down to just above or below 2.
Interestingly, looking just at the North America trace (amber), we might see the effect of the Zero Population Growth movement (Paul Erlich and crowd) which gained traction in the late-1960s which may have suppressed fertility rates into the 1980s when it began to rebound a bit to “2”. The replacement rate in developed countries is considered to be 2.1.
Africa still remains both poverty-stricken and saddled with a high fertility rate: 60 percent of the population in Africa is under 25 years of age, it is literally a continent of children.
Doesn’t look like there is a human fertility problem (male or female) anywhere.
Spermaggedon seems to be something we can add to Patrick Moore’s list of “Fake Invisible Catastrophes and Threats of Doom”.
For better or for worse, humans keep reproducing and the human population keeps growing.
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Dr. Levine and his co -researchers may have found something – and it may be declining sperm counts and total sperm concentrations. And maybe “if things kept going that way” (trend lines extended far into the future) it may affect human fertility. It has not done so as of yet.
Whatever your viewpoint on human population growth may be, it is clear that there is no fertility problem slowing down our burgeoning numbers. In the Most Developed Nations (USA, UK and the Empire, EU) fertility rates are generally below the Replacement Rate. Immigration to the Most Developed Nations results in growing total populations in those countries.
The most hopeful solution to “over-population” is to help poorer nations raise their standard of living. I put quotes on over-population because it is not universally agreed that over-population exists globally. It certainly exists in the sense that many countries and localities have far more people than they can reasonably care for with local resources.
For the record, my wife and I have four adult children. So, statistically, we have supplied replacements for ourselves.
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via Watts Up With That?
November 22, 2022
“This definitive study … strongly suggests that external factors like chemicals and lifestyle play “a causal role in this trend.Spermageddon — Watts Up With That?