Sperm counts in males across the globe have decreased, which could lead to the extinction of the human species, a new research warned. The study didn't examine the causes of the decline but indicated that chemicals and the environment could be the culprits.
An international team of researchers reviewed 185 studies involving nearly 43,000 men from around the world between 1973 and 2011. They found a 52.4 drop percent in sperm concentration, with the number of total sperm count falling by 59.3 percent in Europe, North America, Australia and New Zealand in less than 40 years.
Humans could face extinction at that rate, warned Dr. Hagai Levine, havelead author of the study into the phenomenon. There is no clear evidence for the reason behind this apparent decrease, but researchers hinted at the environment, modern lifestyle and exposure to chemicals like pesticides as the probable causes."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," Levine, an epidemiologist, said. "We must take action -- for example, better regulation of man-made chemicals -- and we must continue our efforts on tackling smoking and obesity," he added.
Levine and his team apparently drew inspiration from a similar finding of Elisabeth Carlsen, who first observed a decline in men's sperm count which she wrote about in a controversial paper in 1992. There, she noted the deteriorating semen quality over the past 50 years based on analysis of 61 publications from 1938 to 1990.
But some experts noted that the new study is more thorough. "[T]he study today by Dr. Levine and his colleagues deals head-on with many of the deficiencies of previous studies," said Prof. Allan Pacey, who hasn't been convinced by past studies claiming that human sperm count has declined recently.