Sunday, August 25, 2013

A Convergence of Readings on Human Evolution

Purely by chance, I happened to read from four different sources last night about human nature and human evolution. They illustrate that we have been confused about human nature for centuries, but that we are making progress in understanding it.

First, I read an article by Ann Gibbons from the August 2 issue of Science: “How a fickle climate made us human.” She reviewed the history of scientific thought about the relationship between climate and human nature. As far back as Raymond Dart, many scientists have noted that hominin evolution began when Africa experienced droughts, starting about five million years ago (at which time the Mediterranean dried up into a salt flat). More recently, this viewpoint is expressed in Steven Stanley’s Children of the Ice Age. Human ancestors had to come down from the trees and start running around on the savanna, perhaps carrying food and babies with them in their hands, rather than having to use their hands as front paws. Even a dog can walk on two legs, but try to get it to carry something in its front paws while doing so. Sounds like a great theory to me. I put the carrying-babies theory into my encyclopedia; I called it the “Let go of my hair! Okay, I’ll carry you” theory. I especially liked it because it gave women an important role in human evolution.

The problem is that the stages of human evolution do not neatly line up with African drought. In 2009, researchers published evidence that Ardipithecus ramidus (“Ardi”) lived in trees and ate fruits and nuts from forests about four million years ago—they walked upright (sort of; they still grasped branches with their big toes) but did not live in the savanna. Also, just because Earth’s tropical and subtropical climate was becoming drier, in general, does not mean that it was doing so in East Africa. Recently, scientists have begun drilling cores in ancient African lake beds to determine what the climate was like in the past near the actual localities where human fossils were discovered. (They can tell that a lake had water if the sediments contained diatom shells, for example.)

What scientists such as Richard Potts found was that rapid evolution in hominins occurred not during long droughts, or during long wet periods, but during periods in which the climate changed back and forth every thousand years or so. That is, when the climate was, as Gibbons put it, fickle. Biological evolution could not keep up with such rapid changes; cultural evolution was necessary, and this put a premium on the capacity for intelligence.

Second, I continued reading E. O. Wilson’s The Social Conquest of Earth. An expert on ant societies and an informed writer about human societies, Wilson wondered what ants and humans had in common that promoted the evolution of advanced societies in each. The answer: very little, other than forming a defensible home site (ant nest, tribal campground). Aside from this, ants and humans became social for different reasons. In the case of humans, the increase in intelligence was made possible by adding meat to a herbivorous diet, and later cooking the meat (an idea recently promoted by Richard Wrangham). For a gracile animal to go hunting, intense social cooperation was necessary. Therefore hunting made us an intensely social species, according to Wilson. He takes it further: this is why we have always been and will always be warlike, a view disputed in a recent book by John Horgan.

Third, I read a Jack London short story, “In a distant country.” In this story, two would-be gold miners during the Yukon gold rush gave up the pursuit halfway, and had to spend the winter in an abandoned cabin with two graves outside of it. During the long winter, they became first uncooperative with and then intensely suspicious of one another. Eventually, they would become two more graves outside of the cabin.

London’s story begins, “When a man journeys into a far country, he must be prepared to forget many of the things he has learned, and to acquire such customs as are inherent with existence in the new land; he must abandon the old ideals and the old gods…” London was not thinking about human evolution, I suspect, but he could have been talking about the hominins watching their way of life dry up or get flooded in Africa during periods of “fickle” climate. And to London, human nature was based on conflict.

Fourth, I tried reading a little bit of Sir Thomas More’s Utopia, written in 1516. It is slow going. More invented the word utopia, from the Greek topos (place) and a prefix; More deliberately confused the prefixes eu- (good) and ou- (no), implying that this good place can really be found in no place. In this book, More speculates about what a utopia might be like. He criticizes the practice, common in England at the time, in which landowners would drive poor families into desperate poverty, which practically forced them to become thieves, and then the government would arrest the thieves and hang them. European governments were creating their own problems. What should be done instead is for government and economy to work in a way such that everyone helps everyone else—not that all are entirely equal, as communists would think, but everyone can make a decent living and contribute their resources to the good of society. More presented this as a story, told to him by the fictitious Raphael Hythloday, about a utopian society somewhere in the recently-discovered Americas, so that he could if necessary tell King Henry VIII that it was just a story. Actually, Native American societies were closer to this ideal than European societies, and maybe More had heard this. More’s view contrasts greatly with not only other philosophers of his time but also differs greatly from those of Wilson and London that I had just read.

Lastly, I read a little bit of George Carlin, the late cynical humorist. Sometimes I wonder if he understood human nature better than either More or London.

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