The Evolution of Human Intelligence

I’ve been reading a book recently called “The Dragons of Eden” which is self-billed as “Speculations on the Evolution of Human Intelligence.” It’s quite an interesting little book, and not so pithy that it becomes no fun to read. Then again, I was already interested in this sort of thing, so I might be unusual in enjoying a read like this- who knows? It has a preface from Darwin that talks about how much Charles himself would rather be descended from a heroic little monkey than a merciless and savage tribal human from times past. I rather like monkeys, but I’ve seen enough Discovery channel videos to know that quite a few of these primates are fairly violent and merciless as well. I don’t think that necessary points toward or away from evolution and it doesn’t really make me feel like I’d rather be evolved from one group or another; I think it just points out that Charles Darwin didn’t watch the Discovery channel. (Before someone comments, I’m kidding!)

The book gets fairly interesting once its gets into the actual chapters. It’s written by Carl Sagan, by the way, which might tell you something. It got me thinking right away about the whole intelligence thing and the function of the brain. I love to read (and write) about the brain – it is as mysterious to me as the ancient pyramids or the missing dryer socks. Sagan points out that humans have expanded their abilities by setting up ways to attain knowledge from outside our bodies and I do think this is quite a fascinating point. It seems obvious at first, but when you consider that many creatures on this earth have to rely on instinct and the current environment, it really is worth looking at more closely. It makes me think about where he is going with all this – that the ready availability of information is a huge aspect of our ongoing evolution.

Sagan also gets into quite a few other aspects of brain research that I find remarkable. He refers to some studies by MacLean who claimed that the brain amounts to something like three little computers. He says that each of these “brain computers” holds its own special intelligence. He goes on to claim that each of these brains represents an evolutionary step. At the part of the brain that he calls the “most ancient” is the spinal cord, the medulla, and the pons. It contains machinery for reproduction and self-preservation. Maclean says that he has done tests that show that a reptile with only this part of the brain is sort of like a car that is idling without a driver. The second portion has to do with the limbic system, which is theorized to contain the beginnings of altruistic behavior and therefore (to MacLean) a sign of higher evolution. The third portion is the neocortex. It is theorized here that the forebrain contains elements of initiative, caution, and deliberation. Maclean takes this as evidence of further evolutionary process in the brain.

It’s an interesting book even if you disagree with the presented theories. I tend to think that some portions are fairly large leaps from what we know to what the author hopes, but I find a great deal of value in speculation so this doesn’t particularly bother me. So, I pass some of these ideas along to you!

Have a nice 4^th of July!