London Independent 
April 26, 2010
If scientists from Mars were to study the human male’s reproductive system they would probably conclude that he is destined for rapid extinction. Compared to other mammals, humans produce relatively low numbers of viable sperm – sperm capable of making that long competitive swim to penetrate an unfertilised egg.
As many as one in five healthy young men between the ages of 18 and 25 produce abnormal sperm counts. Even the sperm they do produce is often of poor quality. In fact only between 5 and 15 per cent of their sperm is, on average, good enough to be classed as “normal” under strict World Health Organisation rules – and these are young, healthy men. By contrast, more than 90 per cent of the sperm of a domestic bull or ram, or even laboratory rat, are normal.
Human males also suffer a disproportionately high incidence of reproductive problems, from congenital defects and undescended testes to cancer and impotency. As these also affect fertility, it’s a minor miracle men are able to sire any children at all. In fact, an increasing number of men are finding themselves childless. Among the one in seven couples now classed as infertile, the “male factor” has been found to be the most commonly identified cause.
Next year marks the 20th anniversary of the WHO conference where a Danish scientist first alerted the world to the fact that Western men are suffering an infertility crisis. Professor Niels Skakkebaek of the University of Copenhagen presented data indicating sperm counts had fallen by about a half over the past 50 years. Sperm counts in the 1940s were typically well above 100m sperm cells per millilitre, but Professor Skakkebaek found they have dropped to an average of about 60m per ml. Other studies found that between 15 and 20 per cent of young men now find themselves with sperm counts of less than 20m per ml, which is technically defined as abnormal. In contrast, a dairy bull has a viable sperm count in the billions.