“…the difference in mind between man and the higher animals, great as it is, certainly is one of degree, and not of kind.” –Charles Darwin, in The Descent of Man

I just finished reading Carl Sagan’s The Dragons of Eden: Speculations on the Evolution of Human Intelligence. It’s a great book, though nowhere near as good as his masterpiece, Cosmos. It’s very intriguing to ponder about the origin of intelligence. The complexity of the brain and ratio of brain mass to body mass seems to be a reasonable measure of intelligence. But what is intelligence, as manifested by behaviour? Is it unique to humans? How and when, did we become “humanly” intelligent? What could be the possible direction of future evolution of intelligence? These are issues that are touched upon by Sagan. Besides, when we refer to violent, rash or cruel behaviour as beastly, we are probably referring to reptilian character, which is probably a part of us, due to our inheritance of significant portions of the reptilian brain. Emotions like love, and generally sensitive behaviour, are characteristic of most mammals.

Perhaps one of the most interesting parts of the book is the one which deals with out ancestors. We all know that we are descended from monkeys, but how closely related are we, to them? Particularly enlightening is the report of a study of chimpanzees, in which they demonstrated amazing aptitude for mastering sign language, complete with syntax and semantics. Aren’t we perhaps too chauvinistic in holding our almost universal conviction that human beings are somehow fundamentally superior to the rest of the living world, and that the world is ours to rule?

Perhaps human chauvinism is not particularly recent. We had a variety of different primate species of ancestors, who were probably contemporaries with at least a few others, which means that their reigns may have overlapped. But where are they today? Why did they become extinct? It’s still a mystery. Perhaps it was just natural selection at work, and the smarter primates survived while the others were wiped out. There is evidence of fractured fossil skulls that belonged to one species of our ancestors who didn’t use tools, who were contemporary to another who did. Could it suggest that the smarter(and shrewder) of the two just killed off the other unsuspecting and defenseless group? Could the line of human beings, that led to us, have exterminated all other relatives they thought intelligent and perceived as  a threat? That could explain why today there are no primates other than us displaying obviously comparable levels of intelligence, but there are species like chimpanzees, who at first sight, is “just a monkey” but upon greater scrutiny, show signs of intelligence very similar to our own.

When I read about this theory, I just couldn’t help imagining how the world would have been, had a few of our ancestors survived. The vision of the world that sprang to my mind was eerily like that in the Lord of the Rings– with a variety of human like creatures co-existing. Little and gentle Hobbits who lived in hilliside burrows, the big Men of Gondor who were known for their skill at machines and warfare, the mysterious elves who were legendarily philosophical.

On the whole it is a great book, though certain portions lack the rigor and flow that is so characteristic of the works of Carl Sagan. For example, there is a chapter called “Future Evolution of the Brain”, which actually talks mostly about the human invention of storing knowledge outside our bodies, computers and machine intelligence, and gives a hint of human chauvinism. It’s a very educative work, and is perfect for the layman wishing to know more about intelligence.