Even after that, the programme could not get to the main point and went off on a tangent as it tried to discover if humans lost their fur because women did not want to mate with hairy men. The late Stephen Jay Gould was suspicious of attempts to dream up evidence-free scenarios from pre-history to explain the modern human condition. "Just-so stories," he called them. Just as Kipling wrote How the Leopard Got His Spots, so Horizon speculated on "Why the human lost his hair." This viewer grasped the real point of the apparently pointless detour only when the scene cut to hunky Scandinavian students having their body hair shaved off on the orders of their Finnish professor. The women back at the Horizon house (yes, still naked) generally agreed that the "after" pictures of the boys' hairless torsos were more attractive than the "before" pictures of hairy chests. A part of what we find sexually arousing is culturally determined, as the varying tastes of men over the decades for voluptuous or boyish women prove. The scientific value of 21st-century women's opinions on men's chests thus told us precisely nothing about the preferences of Pleistocene females.

Only after this titillation could Horizon screw up its courage and surreptitiously slip into its main theme: the discoveries on the evolution of sweat glands. It blurted them out and then scurried back for more nudity, justified by the supposition that most societies have a taboo against revealing our bodies because we do not want our partners to make themselves sexually available to strangers - an argument which is probably true and certainly old hat.

I am willing to bet that no young viewers were inspired to consider a career in biology. Subconsciously at least, they must have noticed that in a programme on nakedness, the only thing the BBC wanted to cover up was the embarrassment of an intelligent interest in science.