Big Brain Theory - A Conversation with Andrew about Evolution

Earlier this week I was referred to a fellow blogger who had just posted about the evolution of a larger brain size as (largely) a result of eating meat. It's a good story at Live Like Dirt. I think that I like this site, as it talks a lot about some subjects that I find fascinating, and the author, one Andrew Holmes, seems quite knowledgeable in his field.

I shared with Andrew my meager thoughts on humans eating meat and how that might or might not impact brain size. You may read, recall, or re-read them here, and here.

Andrew did me the kindness of reading these, and then promptly posted a tutorial on how the human brain evolved, and the importance...the necessity...of eating meat to make that happen. That post is back on the Live Like Dirt blog.

Now that we're all caught up, I do have some responses and thoughts to further the discussion.

In opening, Andrew took issue with my suggestion that humans were not  designed to eat meat. His assertion is that humans weren't designed at all, and that evolution is a completely random and stochastic process.

Without burning too much of anyone's time, I'm hoping that he and I can agree to disagree about this point. When I look at many aspects of the human body, I can't deny that it was clearly designed. If I were to accept this development as a random stochastic process (and this may seem counter intuitive), then I would have expected to see more than one species in the history of the world having evolved a larger brain.

Much like there have been multiple large-tooth cat species (as in saber tooth) in the archaeological record, and there have been a few different forms of elephant-like creatures (mastodons, mammoths, elephants...), I would expect to see that there would have been more than one creature that developed large brains (our sized brains).

In a random process, it is my experience that when you see one instance of an output, you will see it again. If you consider big brains to be a 1-in-a-billion statistical deviation (wild ass guess, right there), I think (with no data, mind you) that we should have seen this evolutionary big brain development at least a few times in the half billion years that the countless life forms have been blundering about.

Could this mean that big brain evolution isn't a result of a random, stochastic process? Could be. I don't know for a fact; all I'm doing is thinking and theorizing...asking questions in the dark. So, Andrew feels that it's not a design, perse, and I think it is. Who's right? I don't know. But his answer leaves me with questions, and mine doesn't. Am I right? I don't know.

I think that one reason why I do spend so much time on this point is that we both feel that it's important. Also, the way I read Andrew's response, this particular point reads as though it's absolute, incontrovertible fact. That may not be the intent, or the real case, but it sure reads that way to me. It reads to me like he dismisses the design theory as an impossibility, and that brings a quote to my mind:

If an elderly but distinguished scientist says that something is possible he is almost certainly right, but if he says that it is impossible he is very probably wrong.
~Arthur C. Clarke

Andrew then walks through what I will admit is a very likely scenario about things that contributed to growing our brains, but even while the assertion reads to me like "this is the way it happened", it's peppered with probabilistic language such as "could provide", and "more likely", and other similar language. The use of this language makes it impossible for me to disagree with the message (which is to say I agree: the large brain could provide an advantage, and would be more likely to pass on their traits...excellent writing, in my opinion).

David says, "The reason our ancestors didn't evolve larger brains prior to six million years ago is because meat eating was probably a much less frequent activity at that time."

This is a confusing sentence to my simple mind: it starts out by telling me that it's going to explain why we didn't evolve a large brain earlier, but then say "probably". It suggests that meat is the reason...probably.

Is it? I don't know.

David then says, "I think that's a pretty good explanation for how humans evolved to have such large brains." I think so too. Is it THE explanation? I don't know.

If you like news about the history of the world, though, it looks like Live Like Dirt is a good place to find snippets of it.