Men from developed nations, in particular, are struggling to reproduce.
Men in North America, Europe, New Zealand and Australia are losing their sperm rapidly. A new study from the Hebrew University of Jerusalem found that the total decline has amounted to 59 percent over the past forty years, which the researchers have described as an “urgent wakeup call… that is likely to get worse rather than better.”
The study, led by Professor Hagai Levine, was published in Human Reproduction Update earlier this week.
“By screening 7,500 studies and conducting a meta-regression analysis on 185 studies between 1973 and 2011, the researchers found a 52.4 percent decline in sperm concentration, and a 59.3 percent decline in total sperm count, among men from North America, Europe, Australia and New Zealand who were not selected based on their fertility status. In contrast, no significant decline was seen in South America, Asia and Africa, where far fewer studies have been conducted.”
There have been reports of decreased male fertility over the past quarter-century, but the related studies have been criticized widely among the scientific community. This one, however, is different. Even skeptics, such as Prof. Allan Pacey of Sheffield University, admit that Levine’s team has done excellent and thorough work. BBC quotes Pacey:
“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.”
Levine, who is an epidemiologist, told BBC that if the current decline continues, humans could become extinct:
“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. Eventually we may have a problem, and with reproduction in general, and it may be the extinction of the human species.”
Despite this dire outlook, the study does not offer any concrete suggestions for why the decline is occurring. Based on other research, most people attribute diminished sperm counts to environmental factors, such as chemicals in consumer goods, pesticides, and plastics, particularly endocrine disruptors; lifestyle factors like obesity, smoking, diet, or even watching too much TV; and prenatal chemical exposure.