Aquatic Apes, Sleek People: Part II
Posted By Paul Kotik on 1 August 2005
'So', you say, 'we, the people, are descended from a population of apes that spent a few million years splashing about in the drink. A marvelous and welcome addition to the resume of any imaginative freediver, to be sure, but can you prove it?' Swell theory, but let's talk science.
All right, then. Attorneys for all parties to the evolutionary debate ( the Creationists are not named in this brief) have stipulated that way-back-when, there existed a primate species we'll call LCA - the Last Common Ancestor. It lived in the lush African forests. The last common branch in the family tree of humans, gorillas, chimps and bonobos. Then stuff happened, natural selection did its thing, and now one species turns the crank and another dances.
The Standard Theory, the one you'll be taught at Oxford, says that some populations of the LCA got to be spending more time in the wide open spaces ( the savannah) that came into being at some point, and that adaptation to the grasslands made us as we are today. Forest - to- grasslands - to- Club Med.
The Aquatic Ape Theory (AAT) says that what happened to the LCA groups that became our ancestors was that they got to be spending a lot of time in and around water, did some adapting to those conditions, and then reverted to the dry life. Forest- to- waterworld- to- grasslands- to -Club Med.
So, which theory does science prove to be true ?
Here's the thing, my fellow aquanauts and only friends: science (the one with the lower case 's') is not in the business of proving theories to be true. In fact, science's definition of itself says flat out that it cannot prove a theory to be true. Rather, science is about proving theories to be false, and regarding competing theories as Best of Show while vigourously trying to prove them false, too.
So what good is science if it can't prove its own theories ? Well, it turns out to be helpful to have understandings which are pretty good, even if imperfect. We see and act according to our best current understanding of things - because, literally, we don't know any better. It works. It has gotten us neoprene, antibiotics, the Boeing 747 and the electric guitar, among other things.
Okay, then how do we decide a theory is bogus, so we can drop it or modify it or take it out and shoot it behind the barn ?
One input is the evidence, Dr. Watson, the evidence. If, for example, we have a nice theory that says heavy objects always fall faster than light objects, and we observe a case of a light object falling faster than a heavy object, we might, if we determined the observation to be reliable, be inclined to revisit the theory.
More complex theories, like the AAT, are a little harder to falsify in this way, by counterexample. If we say that a particular characteristic of homo sapiens, say for example face-to-face copulation, is the consequence of an aquatic interlude in the species' evolutionary history, producing another primate species that also copulates face-to-face but for which there is no other evidence of an aquatic past does not shoot the AAT down. An anatomical, physiological or behavioral characteristic can, in principle, serve multiple functions and can, therefore, have been an adaptive response to a variety of selective pressures.
Sometimes we get tipped off when new data shows our theory to be at odds with some other, more basic theory which has withstood so much pounding over the years we treat it as if it had been proven true. For example, we are pretty sure that in order for A to have caused B, A had to come before B. We don't like the idea that something that happened today caused something to happen yesterday. This is almost beyond dispute: it devolves from our definition of 'cause'.
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