(Contains cold, mean facts beating up a cute little theory. Reader discretion advised)
This is a story about a young man, a non-scientist, playing at science for fun and personal satisfaction. Join me below the fold for a tale of amateur intellectual investigation!
I first heard of the aquatic ape theory about twenty years ago, when it had sort of a renaissance, and I really liked it. To summarize, it says that the major structural
innovations of our hominid family, the hips, feet, and knees, were the result of an
aquatic stage in our early evolution.
But this theory offered to explain even more. We have subcutaneous fat that our ape cousins lack, but is common among aquatic mammals. Our body hair is very short and fine, almost invisible, like a some marine mammals. The hair of the shoulders and back grows in a pattern unique among primates that makes us more hydrodynamic. And who else has a nose like ours? Try diving in the river with a chimpanzee nose, see how that feels on your sinuses. It even accounts for the increased adipose tissue in the female breast. In case of emergency, your boobs may serve as a flotation device! (Okay, I don't think that last one is officially included on the list.) But what a theory!
Incidentally, at about this time another theory had been proposed that said our bipedalism (which, let me stress, involved a really major restructuring of the skeletomuscular system over a surprisingly short period of time) was a response to environmental changes. This theory stated that Africa, in certain regions, had gotten hotter and drier, therefore our distant ancestors needed a way to beat the heat. Their solution was to reduce the total amount of solar radiation absorbed throughout the day. This was accomplished through bipedalism. Pffft. Boooring!
I wanted to show myself that the nifty water ape theory was right, and I could see just how to do it. Living in water, even part-time, exerts strong evolutionary pressures that some of our mammalian relatives have already been exposed to. I
would catalog the differences between chimpanzee and human pelvic bones and then see if the pelvic structure of aquatic mammals was intermediate between the two.
What I found instead was that, if you started with a chimp pelvis and tried to design
something that was different in the exact opposite way of how a human's is different, you'd have a sea lion pelvis. Or that of a walrus or seal. Same story with sea and river otters, if less pronounced. To make matters worse, the leg bones of these creatures are very short and thick while their feet are broad and splayed, with long toes. Again, the opposite of our long legs, narrow feet, and stubby toes when compared to a chimp. So...you know. Shit. That pretty much wrapped it up for me. All these changes in the aquatic species allowed for increased speed in the water. I tried to imagine an environment where the ability to evade predators was outweighed by the ability to...? Wade? I know what grasping at straws looks like. It was over.
But I had shone the light of truth on a small part of the universe, even if only for
myself. And I had no difficulty practicing the Zen of Science and letting go of the
theory, unlike some people I could mention. The Rule of Cool doesn't apply to science, you guys!
What about that boring theory, the one about responding to climate change? At the time, if I recall correctly, we were still saying that bipedalism freed our hands for other tasks, as if that were an explanation rather than an observation. I decided to test this theory too. If I couldn't falsify it, then I'd have something more satisfying than that free-the-hands thing. If I could, then I'd be stomping on a theory I'd never liked in the first place. Win-win!
It was easy to come up with an experimental test, too. I made three clay models, chimp, human, and baboon, and let them air harden. I'll explain the baboon in a
minute. The models had thermometer-sized holes in the head, chest, and groin. Using a desk lamp with one of those old-fashioned Edison bulbs to provide radiant heat (remember, before the curly bulbs? Man, they wasted so much power) I took a lot of temperature readings with the "sun" at different angles.
Okay, about that baboon. They're primates, but their overall form is similar to your standard quadruped in that the back is more or less parallel to the ground (during locomotion) and the shoulders are close together. They don't have broad backs, they have deep chests. I figured that would be an easier form to evolve and I wanted to see how it handled the heat. If it were equal to or better than ours, I would consider this thing busted.
Unfortunately, the actual data points I collected are long gone, but I remember the overall results clearly. The baboon did okay. The poor chimp did terribly. The upright form was impressively good at not absorbing the heat. Huh. How about that.
Although the results of my investigation were not at all was I was hoping to find, I really did get a lot of satisfaction out of using the basic precepts of science to gain a deeper understanding of the world. I can do science, me! In addition, I found it unnecessary to completely abandon the aquatic ape theory that chimed such a harmonic resonance in my brain. After all, when humans are free to live where we will, we tend strongly to choose riverbanks and seashores. The warpath ran through the forest, for all other business you used the river. We think water is awesome. In my humble opinion, the aquatic ape is us.