Three new studies into male fertility suggest that sperm counts among American men, at least, have actually increased slightly in the last twenty years. There is also intriguing evidence that residents of New York City consistently demonstrate far higher sperm counts than men in other US cities.
While the revelation hands welcome machismo rights to all Big Apple males, it is also the basis for another important conclusion; that previous studies suggesting falling sperm counts were grievously flawed because they failed to take such geographical variations into account.
A Danish scientist first alerted the world to the possibility of declining sperm counts in 1992, showing that sperm counts among 15,000 men in 20 countries had dropped by almost half in 50 years. Two subsequent studies, in Belgium and France, drew similar conclusions, and raised concern over the quality of sperm.
The new findings, which are certain to provoke furious debate in the medical fraternity, are detailed in three reports in this month's issue of the US journal, Fertility and Sterility.
One study analysed the semen of 1,283 men who made deposits to sperm banks in three cities - Los Angeles, New York and Roseville, Minnesota - from 1970 to 1994. Its author, Dr Harry Fisch of the Columbia-Presbyterian Medical Center in New York, found a "slight but significant increase".
There may be no explaining - scientifically anyway - the elevated sperm counts of New York men, who boast 131.4 million sperm per millilitre of semen. That is more than 50 per cent higher than the measly 72.7 million registered by men living in Los Angeles.
Much more important, says Dr Fisch, is to understand the main bodies of research that have suggested worldwide declines in sperm counts were misleading because they compared new data gathered in Europe and the Third World with earlier results from New York, where the counts have always been high. "Take New York out of those studies, and there is no decline," he said yesterday.
Non-scientific speculation about sperm-heavy New Yorkers is already under way. Among the theories: LA guys spend too much time in hot tubs (not good for the testicles), tight shorts (likewise) and in fitness gyms. Or there is the supply-and-demand angle: New Yorkers have more sex than men anywhere else.