Will our lifestyle lead to our extinction? New findings from an international team of eight researchers indicate sperm counts in men from North America, New Zealand, Australia, and Europe have halved in under 40 years. Lead author epidemiologist Hagai Levine of the Hebrew University of Jerusalem told the BBC, “If we will not change the ways that we are living and the environment and the chemicals that we are exposed to, I am very worried about what will happen in the future.”

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Sperm count studies have been controversial in the past. This recent one, published this week in the Oxford Academic journal Human Reproduction Update, is one of the biggest assessments ever undertaken, according to the BBC. Researchers pored over 185 studies between 1973 and 2011. Levine detected a 52.4 percent decline in sperm concentration and 59.3 percent drop in total sperm count in the men from those regions of the world listed above. The rate of decline continues and may even be increasing, according to the researchers. They didn’t see the same decline in men from Africa, Asia, or South America, but said there have been fewer studies from these regions.

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Levine told the BBC, “Eventually we may have a problem, and with reproduction in general, and it may be the extinction of the human species.”

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Skeptics say a large proportion of past studies that have pointed to sperm count drops have been flawed, such as only including men who have gone to fertility clinics, and would be likely to possess low sperm counts. But the researchers involved in the new study said they accounted for some of the flaws.

Professor Allan Pacey of Sheffield University told the BBC, “I’ve never been particularly convinced by the many studies published so far claiming that human sperm counts have declined in the recent past. However, the study today by Dr. Levine and his colleagues deals head-on with many of the deficiencies of previous studies.” Other scientists praised the quality of the new study but said it may be too soon to come to the conclusion that humans could be on the path to extinction.

Researchers at institutions in Denmark, the United States, and Spain were also part of the research.

Via the BBC

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