Monday, January 29, 2007

The evolution of intelligence

I never write about evolution or debate about it because I don't know enough about it. I don't know enough to defend evolution or refute it. Scott Pruett, who does the Pensees blog, recently wrote one on Eugenics that got me to thinking about something, though. This isn't a polished thought I had, but since I did say in the beginning that "the things I write down are not meant to be things I've completely thought through and refined," but that they "are my initial ideas about things--things that just pop into my head--that may some day be developed further and refined or abandoned," I decided to go ahead and share my thoughts with you.

There's no doubt that our scientific and mathematical knowledge has greatly increased over the last few thousand years. It's incredible what we've accomplished--calculus, nuclear physics, molecular biology, space travel, etc. It would be impossible to go through all the amazing stuff we've been able to do. I think there's also no doubt that doing these things requires quite a bit of intelligence.

Now here's the interesting thing for me. It doesn't seem like our intelligence has increased at all over the last few thousand years. In fact, I'm quite certain it hasn't increased at all in the last 10,000 years, at least. There are a couple of reasons why I say that.

First, because North and South America were pretty much isolated from the rest of the world about 10,000 or 12,000 years ago. When Europeans arrived about 500 years ago, they found the natives basically living in the stone ages (maybe with the exception of the Aztecs, Mayans, and Incans). Yet it turns out there is no difference in intelligence between native Americans and Europeans or Asians. Or at least if there is a difference, it's not significant enough to tell. That means that in spite of living in the stone ages, these people were just as intelligent as the people who developed radio, space travel, and nuclear bombs.

It would seem to me to be an incredible coincidence if two people who lived in isolation from each other for 10,000 years or more, under very different conditions, nevertheless evolved exactly the same. There's really no difference between Asians, Europeans, and native Americans. That leads me to believe Asians and Europeans were just as intelligent back when they were living in the stone ages, too. In fact, all mankind must've been just as intelligent when living in the stone ages as they are today.

Second, ancient civilizations like China that go back 10,000 years or so have left records that seem to indicate an intelligence no different than our own. All we have done since then is build on previous knowledge. That's the only reason we are advanced now. It isn't because we're smarter. It's because we have a long history of built-up knowledge behind us.

These two observations make me pretty certain that humans across the globe have not evolved intellectually in the last 10,000 years. 10,000 years ago, all of us, with the exception of the Chinese, were living pretty primitively. Up until then, we likely always had. I doubt we'd find more advanced civilizations by moving back farther in time from then. That means humans were far more intelligent than necessary back then.

As I said above, I don't know that much about evolution. But from what I understand, there are basically two mechanisms that cause things to evolve--mutation and natural selection. Mutations occur during reproduction. The offspring gains something in its DNA that wasn't there in its parents' DNA. There are three kinds of mutations--those that result in a disadvantage, those that result in an advantage, and those that make no difference. Rarely do you ever hear of a creature being born with a deformity that it advantageous to its survival, but you always hear about deformity resulting in a disadvantage. Who knows how many mutations make no difference at all! Nature tends to weed out disadvantages, and it selects advantages because advantages make it easier to survive and reproduce whereas disadvantages make it more difficult.

You would think, then, that a mutation wouldn't propogate unless it gave the species an advantage. Since mutation is necessary before natural selection can operate to cause a species to evolve, several generations of mutation and natural selection have to occur before a species as a whole can change significantly. Each generation would have to mutate in a beneficial way that built on the previous beneficial mutation.

In this case, I've been talking about intelligence. I can see how evolution could produce intelligent creatures, but that intelligence would have to be suited to the world those creatures lived in. Unless some added intelligence gave a creature an advantage, it would be a superfulous mutation. But humans were far more intelligent than necessary 10,000 years ago. That means that for several generations, superfulous mutations kept adding to each other. We kept getting smarter even though natural selection wasn't causing it.

I find it incredible that there is such a diversity of races in the world, yet no noticeable different in intelligence between them. There are different races, I presume, because they all evolved in such a way that they would be adapted to their divers environments. That means that to an extent, they have been evolving independently from each other for a long time. Yet intellectually they're all the same. If they evolved pretty much independently, yet they have all reached the same degree of intelligence, then I would find it hard to believe their intelligence evolved independently.

This last observation leads me to believe our intelligence hasn't changed at all since migrating people first began to develope noticeable differences in their races. Surely that goes back much farther than 10,000 years ago. Imagine how primitive our ancestors must've been then, yet just as intelligent as we are today.

There really are a lot of things that evolution doesn't explain to me. I say "to me" because I'm sure somewhere somebody has managed to account for these things under evolutionary theory. This intelligence thing is just one example. Another example I've found striking for longer than intelligence is our appreciation of art, music, natural beauty, humour, and things like that. What advantages do these things have? And why is it that they are universal? Why do so many people find sunsets to be "beautiful," and why do so many people have a sense of humour? Why does anybody have a sense of humour?

I know that my reasoning above could be all faulty. I know my knowledge of the subject is primitive. But these things don't cause me to want to reject evolution altogether. They do make me highly suspicious, though, that there aren't exceptions to evolution. Even if I grant that species have changed significantly over time, I doubt that mutation and natural selection are the only means by which they have changed. I'll say something more about that in the next blog.


Psiomniac said...


I commend your humility. I have read this post and sketched in my head the outlines of answers, each of which, when I think about it, would run to several thousand words in order to begin to explain adequately.
I am no expert on evolution of course, although I have read a lot of books on the subject. Nothing that you have raised in this post poses a serious problem for evolution theory as it is presently understood in my view. I agree that the physiological capacity for intelligence is unlikely to have changed much over the last 10000 years or so. We stand on the shoulders of giants.
I urge you to read some good books on the subject, I think it would be an enriching experience.

Sam Harper said...

I have read this post and sketched in my head the outlines of answers, each of which, when I think about it, would run to several thousand words in order to begin to explain adequately.

I appreciate you sparing me. I don't think I could handle a post that long.

I have read some stuff on evolution, and all it has done is let me know how much there is that I don't know. It seemed so overwhelming to me that I just gave up on it. We can't be masters at everything, so I'm probably just going to let this one go. Not that I won't ever read anything on the subject again. I'm sure I will. I just don't have any plans to really study it. I must choose my battles.

Paul said...

You've captured the essence of one of my indirect challenges to evolution! I haven't actually seen anyone else formally explore this issue. I don't think it is a logical defeater to evolution, but it is a real puzzler.

We seem to have had the equipment for some really heavy mental lifting (and delicate skills) long before those jobs ever came available. It's kind of like an herbivore evolving into an awesome killing machine in an environment without prey, and then at some later point it gets turned loose among the teeming herds of the plains. Massive brainpower is not biologically cheap. A big head is hard to birth, and a large brain is a real energy and heat sink. There's no selective advantage unless this thing is paying big dividends.

What gets me is that we seemed to have had a brain fully equipped to compose symphonies, build marvels, and understand the most abstract concepts of mathematics and physics long before such things were feasible to realize. You could take a time machine and grab an ancient African, bring him up in a modern education and he would probably be no different than any other human today. And it doesn't even seem that there is a limit to our ability to achieve through our present minds.

And besides just being able to do all this complex intellectual stuff, we seem to have been invested with the driving passion to do it. I can, evolutionarily, understand our desire for sex and community, but literature, art, music, theater, math, etc.? That's pretty abstract and nonessential stuff! If you've got competing tribes who prefer to steal your women and have a passion for banging heads with stones, then sitting around banging drums and painting buffalo becomes kind of superfluous.

Oh, and by the way, I think you may have over-estimated the timeframe for advanced society in China. I don't think there's evidence for much of anything anywhere advanced prior to about 4000 BC. Things started really hopping around the world at that time. My theory is that things spread from Sumeria, both east and west.