Many years ago, when I was young and handsome, a friend inveigled me into taking a small role in a film he was making ó a proper film, with a real budget and a commercial release, though mercifully it never got much attention. It was a Cold War spoof called The Last Straw in which the Soviets were plotting to bring the West to its knees by causing the sperm count in Western males to collapse, and I got the Dr Strangelove role.
You cannot even find this film on YouTube now, Iím pleased to report. However, it did give me a head-start on considering the appalling consequences of a drastic fall in the sperm count of Western men. This comes in handy at the moment, since that is now actually happening. In the 15 years between 1989 and 2005, according to a study just published in the journal Human Reproduction, the sperm count of French men fell by one third. More than 26,000 men were tested in the study, and the number of millions of spermatozoa per millilitre of their semen was falling by almost 2 per cent a year. If that rate of decline has been maintained since the study ended, the count will be down by another 13 per cent now.
The virtue of the French study is that the country has the Fivnat database, a record of some 440,000 cases of infertility problems at 126 government-funded ďassisted fertilisation centresĒ from the 1980s onwards. The researchers chose only the 26,200 cases where the problem had proved to be complete sterility in the female partner ó which presumably meant that their male partners were a random sample of the population.
Treatment for infertility is free in France, so there should be no income bias in the data either. For those reasons it is probably the most reliable survey of changing sperm counts that has ever been done ó and it documents a steep fall in a relatively short time.
There are really three questions here. One, is the same thing happening elsewhere? Two, whatís causing it? And three, how much does it matter? Most other scientific studies in developed countries in the past 20 years have also found falling sperm counts, though none of them matched the French one in scale and precision. There is no comparable research on the trend in developing countries, but it is at least plausible that this may be a global phenomenon.
That mostly depends, of course, on whatís causing it. If itís environmental factors, are they the same in rich countries and poor ones? A common theory lays the blame on chemicals in the environment like Bisphenol A, found in some plastics, that disrupt endocrine function and change hormonal balances. Another theory blames smoking, drinking alcohol, and high-fat diets. These factors vary from one country to another, and more research is needed. But let us suppose that the trend is continuing, and that sperm counts are also declining in developing countries. Should you lie awake at night worrying that this is a threat to human survival?
Definitely not. If youíre really worried about keeping human numbers up, then you should be doing something quite different at night. And afterwards, you might lull yourself to sleep pondering whether it would really be such a bad thing if the birth rate dropped for a while.
If this decline in sperm counts is caused by environmental factors, then it can almost certainly be reversed eventually by doing enough research and then eliminating those factors. In the meantime, however, we are passing through the astounding total of seven billion humans beings, on our way to nine or ten billion. Thatís far too many for this finite planet, and a rapid decline in the birth rate, even to below replacement level, would be a good thing.