review

"James has just ejaculated a whopping 700 million sperm," announced the even tones of Barbara Flynn. To help you visualise this, the film included a business-end view of a penis, clearly suffering the effects of motion sickness. James rolled back sated, quite unaware that he had just launched a seminal counter- offensive for possession of his lover's cervix. Because if you believe Dr Robin Baker and Dr Mark Bellis, this generative excess (400 million will usually do perfectly well) was the result of James' brief separation from his partner, a separation which, whatever his conscious trust in her fidelity, stirred primal fears of cuckoldry.

Whether you believe Baker and Bellis rests partly on how reliable you think students are in obeying the strict procedures of their research - which involved such indignities as pinning condoms up after lovemaking, like soggy Christmas stockings, in order to collect semen samples. It also depends on whether you want to believe them. Sex and Women: the Inside Story (C4) obviously did, though it took care to point out that their findings and theory remain controversial.

The programme made a good case, though, that sexual behaviour is far more complicated than we sometimes imagine, driven by buried evolutionary calculations. Women, according to some research, unconsciously take steps to increase their chance of being impregnated by a lover rather than a steady partner, using a variety of means, from the timing of their orgasm to skimpiness of dress (one team of researchers had discovered a correlation between ovulation and the clothes worn by girls visiting a Vienna disco).

All this was intriguing - that useful word for theories to which one doesn't quite want to trust one's weight just yet. What was more dubious was the flurried coda in which these speculations were harnessed to a programme of feminist empowerment. Awful footage of a young girl being circumcised was included, as if there were a simple link between such cultural practices and male genetic jealousy (any satisfactory account of female circumcision would also have to include an explanation of why so many women have collaborated in its perpetuation). It seemed odd, too, that the new findings should be embraced so happily by avowedly feminist scientists, not least because they appear to replace a "patriarchal" account of women's sexuality (passive, meek, responsive to male success) with an equally venerable misogyny - that of women as congenitally fickle and lecherous, the helpless prey of their bodily compulsions.

Life Without End, part of BBC2's Coming of Age season, was also occupied with the borders of scientific knowledge - in this case, the science of ageing. It did not start well, with a slavish homage to David Lynch and a thoroughly misleading statistic. "A hundred years ago, you could expect to live for about 40 years," read the caption, "Now you can hope for 75 years. Almost double!" In fact, if you could read that caption 100 years ago, your expectations would have been pretty similar to ours, as you had already survived the high infant mortality that depressed the average.

Christopher Spencer's film went uphill from there - displaying a more clear-minded scepticism about various life extension gurus, and also demonstrating that he doesn't need to borrow his visual style from others. There was almost nothing here that hadn't been seen before - from Durk and Sandy, two pickled hippies who want to live forever, and whose faith in their chemical elixirs is completely mirror-proof (Durk is 52 and doesn't look a day over 60), to the human popsicles in the Alcor corporation's vaults. But it was presented with a nice visual wit, summed up by the admonitory image Spencer chose to end his film - a travelator with a recorded voice warning that "the moving walkway is now ending. Please look down". The end is nigh, in other words.