Why Are Humans Hairless?

I caught a story over at MedicalNewsToday about a prize winning essay which puts forward a new theory as to why our species became less hairy:

Harris' paper describes Stone Age societies in which the mother of a newborn had to decide whether she had the resources to nurture her baby. The newborn's appearance probably influenced whether the mother kept or abandoned it. An attractive baby was more likely to be kept and reared.

Harris' theory is that this kind of parental selection may have been an important force in evolution. If Stone Age people believed that hairless babies were more attractive than hairy ones, this could explain why humans are the only apes lacking a coat of fur. Harris suggests that Neanderthals must have been furry in order to survive the Ice Age. Our species would have seen them as "animals" and potential prey. Harris' hypothesis continues that Neanderthals went extinct because human ancestors ate them.

Now I don't know about anybody else, but I personally think this is a lame explanation. Our ancestors have all been quite ugly and since beauty is to some extent in 'the eye of the beholder', I'm sure we'd look ugly to them too. Arguing that mothers neglect ugly babies is absurd. Babies are ugly (and the phrase 'only a mother could love that face' comes to mind).

There are some more likely explanations as to why we are less hairy than our ancestors. From a 2003 print edition of Scientific American:

When did we lose our hair?

The skeletons of ancient humans-such as the well - known skeleton of Lucy, which dates to about 3.2 million years ago - gives us a good idea of the build and the way of life of our ancestors. The daily activities of Lucy and other hominids that lived before about three million years ago appear to have been similar to those primates living on the open savannas of Africa today. They probably spent much of their day foraging for food over three to four miles before retiring to the safety of trees to sleep.

By 1.6 million years ago, however, we see evidence that this pattern had begun to change dramatically. The famous skeleton of Turkana Boy - which belonged to the species Homo ergaster - is that of a long-legged, striding biped that probably walked long distances. These more active early humans faced the problem of staying cool and protecting their brains from overheating. Peter Wheeler of Liverpool John Moores University has shown that this was accomplished through an increase in the number of sweat glands on the surface of the body and a reduction in the covering of body hair. Once rid of most of their hair, early members of the genus Homo then encountered the challenge of protecting their skins from the damaging effects of sunlight, especially UV rays.

There are also some other alternatives including the aquatic ape theory (which Dennett gives some consideration of in Darwin's Dangerous Idea). From Wikipedia:

Humans are the only primate species in which, over most of the body, hair is so fine and sparse as to reveal the skin under it into adulthood. Baby chimpanzees have thinner hair and visible skin but as they reach adulthood after a year or two (as opposed to more than ten for humans) their fur becomes much thicker. Furthermore, human hair is broadly aligned in such a way as to match fluid flow lines while swimming or sweating. Environments known to give rise to naked mammals are tropical (in some larger-sized mammals such as elephants — which are themselves descended from aquatic ancestors — and some rhinoceros species), aquatic (whales, dolphins, walrus, dugongs, and manatees), semi-aquatic or littoral (hippopotamus, babirusas), and subterranean (naked mole rat).

And here's another theory, again from Scientifc American:

SA: Humans evolved in Africa, along with a lot of primates that are covered with fur. Why did humans lose most of theirs?

NS: We don’t know. There’s a lot of variation in how much of the body is covered with fur in various primate groups. Some are incredibly hairy, and some have considerably less fur on the face and the chest and so on. Primates tend to rely on facial expressions for social communication, and of course the better you can see the face, perhaps the better that social communication works. That doesn’t mean you have to get rid of the hair to see the face. That just happens to be what happened in apes. But that could be one of the reasons why we don’t have hair on our faces.

Whether we'll ever know for sure what the actual truth is, surely the idea that we became less hairy for aesthetic reasons is just daft?