THE year was 1974. As newspaper columnists were busy wringing their hands over the development of in-vitro fertilisation and the prospect of “test-tube babies”, an alarming discovery about male fertility completely escaped their notice.
Comparing contemporary semen samples with historical data, two doctors in Iowa named C. M. Kinloch Nelson and Raymond Bunge showed that there had been a drastic shift in men’s sperm counts over the previous two decades. In 1951, each millilitre of semen contained 107 million sperm; by the 1970s, that figure had dropped by more than 50 per cent – to just 48 million. The average volume of semen from a single ejaculation had fallen too.
By the 1990s, the issue started catching considerably more scientific attention, although some researchers were still sceptical. They blamed differences in techniques, or the fact that studies were mostly on men already having treatment for infertility. Such doubts are now shrinking. “There is a huge body of scientific evidence showing this decline,” says Albert Salas-Huetos at the University of Rovira i Virgili in Spain.
For researchers like Salas-Huetos, the big question is no longer whether this so-called “spermageddon” is really happening, but why and what to do about it. Studies are beginning to shed light on environmental toxins that may be to blame, as well as other lifestyle factors contributing to the problem. With a better idea of the prime suspects, we may finally be able to put the brakes on this trend, or even reverse it.