Last Night's TV: The good doctor laid it all on the table

Just don't expect me not to snigger, that's all. I know we're supposed to be grown-up about these things and that today's children are, notionally at least, growing up hideously ignorant about sexual health and that it's a thoroughly good thing that Dr Alice Roberts is giving us a brisk introduction to our reproductive organs to kick off her series Don't Die Young. But when she talked about "my user's guide to the male reproductive organ", I'm afraid I couldn't repress the unruly boy slouching on the back row who wanted Miss to explain precisely what she used it for. Was she going to offer star ratings? Handy tips for the novice handler? Small boy piped up again when she delivered one of her pieces to camera from the crotch of the Cerne Abbas giant and, I regret to say, when we were introduced to her male guinea pig, an events organiser called Mark Smallman. With a name such as that, Mr Smallman must have had a very wearying time in his teenage years, but he can now lay the past to rest. His testicles, we have it on sound medical authority, are an excellent size, and the sample of semen he had tested looked as busy as a municipal lido in the middle of a heatwave. As in the lido, there always seems to be one maniac, head down and doing a splashy sprint from corner to corner.

If you thought that set a benchmark for unabashed self-exposure, you'd reckoned without Dr Alice's commitment to unflustered instruction. Half-way through her programme on the female reproductive organs, she slid herself into an MRI scanner and took us on a tour of her generative plumbing. "There we go," she said proudly. "My vagina on national television, my mum would be proud." True, the organ in question was chastely blurred into monochrome by the scanner's screen, but I'm not sure many presenters would have pointed out their own rectum with such sangfroid, or so casually identified the plinth of buttock fat on which the whole assembly rested. Does my bum look big in this? Yes, but don't worry, even Kate Moss's would.

She's game, is Dr Alice. That's the point, really, along with the fact that she's nice to look at and can dissect a pig. Should the producers decide that a period is best diagrammed by getting her to roll in a giant hamster ball along a massive outline of the fallopian tubes, she'll do it without moaning. And she asks no awkward questions about the precise rationale for creating cuddly-toy versions of the bacteria and viruses responsible for sexually transmitted diseases, and asking passersby whether they can identify them. What's that about? Making chlamydia cute and turning syphilis into a cot toy? If people are to be persuaded to put a layer of latex between themselves and either organism surely they need to look as repulsive as possible?

Still, Dr Alice has a good bedside manner and the programmes do contain some fascinating information, even if you'd want some of it subjected to a peer-group review before taking it as gospel. A study of American lap-dancers, for example, revealed that their average take in tips at the peak fertility during their cycle was nearly double that during their period, which some have taken as evidence that women give off an invisible signal of their fecundity. Whether the experiment included controls to exclude variable rates of grumpiness wasn't revealed.

Five's Sex and the Neanderthals: Revealed explored the contentious theory that our closest human ancestor didn't die out as a result of prehistoric ethnic cleansing but may have been miscegenated into non-existence. "They were all dirty, they were all smelly, they were basically people and, hey, why not? Sex happens," said one of the scientists advancing the idea that Neanderthals had simply been absorbed. Given that men have been known to have sex with farm animals if nothing better is available, it didn't seem implausible that some Cro-Magnon type would have tried it on one dark night in a cave. On the other hand, since interracial dating can still cause friction and disapproval in some communities, it was hard to imagine that inter-species dating would have gone down well with primitive groups.

The truth is that no one knows for sure, nor is likely to any time soon, since all the evidence dates from some 40,000 years ago, and even the guys on CSI would have trouble working up a categorical lab result from that. Trying to sequence Neanderthal DNA from the confusion of genetic material found in an ancient bone, one expert explained, was like trying to reconstruct a shredded copy of War and Peace that had been mixed in with the fragments of 20 other shredded novels, and not having a clue what any of the books should look like. That the meat machines described by Dr Alice Roberts should have brought us from living in caves to the brink of being able to achieve such things suggests that sex must be worth all the trouble that comes with it.