The aquatic ape hypothesis (AAH)

It's personal; this one got me at first.

The idea is that many of our morphological differences with the chimps (less hair, bipedalism, nose shape, body fat distribution, fat babies, possession of a "diving reflex", etc.) can be explained by postulating the existence of an intervening human ancestor that had experienced the selective pressures of an aquatic or semi-aquatic environment. So according to this view, a lack of hair is supposedly meant to help us swim faster; bipedalism to help us wade in the shallows; our strangely shaped noses to keep water out; and our body fat is actually blubber and so on. I'm probably underselling it, but it's actually quite a seductive idea. Especially when first encountered, say, in this BBC documentary which features Elaine Morgan (the AAH's best friend), or during her TED appearance.

After some reflection, though, I have discarded this rather endearing meme. I mean, babies do look pretty cool in the water (okay - some of them), but if an aquatic environment really shaped us morphologically to such a degree, why do we drown so easily? why does our skin become water-logged? why is swimming so bloody hard? and why can't I see better underwater? The more I thought, the more it all fell apart.

Let's be clear: no one is saying that bodies of water were completely absent from the world of our ancestors. Obviously, we need water to live. But that's not what the AAH is about; the AAH makes very specific claims, most of which either lack, or are undermined by, evidence. Here is a cool site which is dedicated to dismantling the AAH point by point, if you want to investigate it more thoroughly.

Why is all of this even important? Well, ever since I realized that the AAH is actually somewhat fanciful, I seem to feel slightly better about swimming fewer laps in the pool, and not liking oysters.

More importantly, Elaine and other proponents claim that the scientific community is dismissing their arguments out of hand, and failing to offer alternative explanations. There are in fact many different alternative explanations, and, as I noted above, there are many points that the AAH does not address. AAH adherents thus seem to me to be arbitrarily connecting the dots; constructing a constellation which ignores dim or merely inconvenient stars to trace out an interesting image which subsequently appears obvious. They embrace evolution by natural selection, and seek to understand actual observations via a plausible explanation. But they also cherry-pick the facts instead of letting them speak for themselves. The road to a better understanding of our world is littered with many a stumbling block.