The Evolution of Individuality

Last fall, when the leaves were turning, the cottonwood trees were patchworks of yellow and green. Each branch seemed to be on its own schedule for leaf fall, even though all of the branches were on the same tree, had the same genes, and experienced the same environmental conditions. I am not sure why this pattern occurred. But it got me to thinking about the evolution of individuality.

One of the common themes in science fiction over the decades has been the rise of the clones. Maybe some mad scientist somewhere is creating clones of humanoids. Or hordes of machine-like, identical outer space monsters attack Earth. We fear the power of genetically-identical hordes, whether of insects or humans. When a group all looks alike to us, we assume every member of the group is identical, even when they are not. To prejudiced European eyes in the past, large populations of Mongols or Chinese or Japanese looked alike, even though this is not true. In the history of the eighteenth-century American frontier, all Cherokees looked alike to the whites, and the Cherokees could not tell the difference between Englishmen and Americans. Individualistic Americans looked with fear on the superficial sameness of communists. To human eyes, all bees look alike. We fear their uniformity, because it looks to us as if they are merely parts of a gigantic monster network, no single individual of which may be dangerous. But we fear the mindless devotion of each individual to a collective superorganism. In fact, most biologists think of swarms of bees, ants, or wasps as organisms whose components are the individuals.

But much of this fear is based on a misunderstanding of evolution. Even in conditions of near or complete genetic uniformity, social evolution favors individuality. As identical twins grow up, they usually diverge in their personalities, each wanting to carve out his or her own niche in the little world in which they spend their childhood. In evolving populations, even the slightest genetic differences can become the basis for sympatric speciation, a divergence into different species even when the organisms are located in the same place.

Robots of any given make really are all alike, all programmed to respond the same way to circumstances. This is never the case with biological organisms. But even with robots, if the robot creators should incorporate a genetic algorithm into their control systems, robots can diverge into different, as it were, personalities. Evolution, whether biological or social (or, in the case of genetic algorithms, computational), always produces diversity. Of course, stabilizing selection can then eliminate some of this diversity. But new diversity always comes along.

While I do not understand why cottonwood trees in autumn are patchworks of yellow and green, they remind me of the never-ending evolution of diversity.