A CURIOUS THING happens to science correspondents in the run-up to Valentine’s Day. Suddenly we are overcome by a primeval urge to report that our romantic behaviour today is not under our control, but was hardwired into the brains of our cave-dwelling ancestors and handed down the generations like a biological baton.

Our brains today, so the theory goes, are just slightly refined versions of the brains that evolved to survive on African savannahs. Only those with genes conferring biological “fitness” survived to reproduce; the result is an unbroken line of inheritance, and behaviour, stretching from early human beings to us.

The seductiveness of the theory of sociobiology — or how human and animal behaviour can be explained in evolutionary terms — has seen the theory itself seemingly evolve into a paragon of Darwinian fitness. It has become a master hypothesis able to explain how every human trait, whether it be altruism or aggression, evolved as an adaptation to ensure the genetic lineage was perpetuated.

Why do you become jealous when men lavish compliments on your wife? Because, back then, jealousy was an early warning system that urged people to procreate with their partners before someone else did. One controversial theory even suggests that rape evolved because it allowed men incapable of normal sexual relationships to father children.

Richard Francis, a biologist-turned-writer, says that the parlour game has got out of hand. In his complex analyis, Why Men Won’t Ask for Directions, he complains that sociobiology reeks of “Darwinian paranoia”.

Evolutionary psychologists — who try to puzzle out how modern psychological strategies sprang from ancestral experience on the savannah — are the worst offenders, spinning the tallest of tales from the flimsiest of scientific evidence. They see similarities in the behaviour of other species as evidence of a common evolutionary origin, while ignoring differences. Yet their ideas have come to dominate biological thinking, because they are easy to understand and therefore simple to foist on the media and public.

Francis, 50, knows he is treading a controversial, unfashionable road. Like the late Stephen Jay Gould and Richard Lewontin, he takes issue with some of the biggest names in evolutionary thinking such as Richard Dawkins, Steven Pinker and Edward Wilson. The Darwin Wars, as their tussle has been nicknamed, has turned out to be one of the most acrimonious and enduring modern scientific feuds.

Some oppose Darwinist thinking for largely political or ideological reasons — biology, they protest, should not be invoked to explain or excuse behaviour such as rape. Others, such as Francis, take issue with the fact that the theories are “untethered speculation” about how our ancestors may or may not have lived that largely disregard cultural and social influences on behaviour.

For example, take the common assertion that men have better spatial cognitive skills than women. “They (sociobiologists) would say that in the Pleistocene, man went out hunting and women stayed around the campsite doing domestic things,” Francis says.

“Two possible theories spring from that: the first is that men had to have a better navigational sense because they ranged farther from home. The second is that women preferred men who were good hunters, and so sexual selection was involved. The problem is that we don’t know what went on in the Pleistocene. We don’t know how far the males were ranging. Some people speculate that we scavenged rather than hunted and, in that case, it’s not as clear that women would need to stand back.” The point is, he says, that there is no incontrovertible evidence to support the man-as-hunter premise.

Francis says that when the studies purporting to show superior spatial skills in males have been examined closely, the evidence evaporates. Still, the belief lingers. “Evolutionary psychologists assume that biological factors are paramount. They don’t completely deny cultural or social factors, but they assume them to be secondary.”

The reason that sociobiology has risen to conquer modern thought is that it appeals to the child in all of us. It seems to answer the “why” question — why do we argue, fight, flirt, share or fall in love? But Francis says it is time to escape this adaptationist mindset and realise there doesn’t have to be a “why”. Traits may just happen, perhaps by accident, and confer no benefit.

He cites the mocking bird, which has an uncanny ability to mimic the sounds around it. Did the mimicry evolve to allow the bird to scare others off the same territory? Or as a signal of sexual fitness to potential mates? Francis says that by looking at a “how” question — how birds acquire song — the mystery can be solved. Francis says: “Actually, the mimicry is an inevitable byproduct of the fact that mocking birds learn songs throughout their lives. The mimicry is a mistake. Lifelong learners are subject to picking up extraneous sounds. Here, the ‘how’ biology is an alternative explanation that is more productive than the adaptive one.”

Unfortunately, he says, the sociobiologists have managed to con people that their “why” questions are more meaningful. “The problem is that it’s so easy to concoct these ‘why’ stories; it’s like a parlour game. People are losing sight of the science. I’m not against an evolutionary perspective, but it’s really important for a popular audience to know that there is another side to the debate.”

Francis says that his book’s title is precisely what we should not be asking. But I can’t resist.

So why don’t men ask for directions? Is it that cavewomen didn’t want to procreate with men who didn’t know where they were going?

“The best I can come up with is that we are socialised not to demonstrate any vulnerability,” Francis laughs. “But that’s a question for the social sciences. I don’t think biology has much to offer here.”

Why Men Won’t Ask For Directions, by Richard C. Francis, is published today by Princeton University Press at £19.95. Times readers can buy it for £15.95 plus £2.25 p&p from Books First (0870-160 8080).