It's worth contemplating. Dr. Vincent Macaulay, a geneticist from the University of Glasgow, thinks it is conceivable that a single froup of hunter-gatherers, possibly no more than 200 people, could be the ancestors of all the humans outside of Africa. This might have occurred some fifty to sixty thousand years ago. Our planet is four billion years old, so the journey beginning somewhere in southern Africa and heading north, in geologic time, happened only yesterday. Talk about serendipity: Did some disgruntled individual sitting around a campfire say, "Is this as good as it gets?" So what else have we got to do?
The 6.5 billion humans currently overwhelming the planet and sowing destruction likely owe so much to so few, and in a relatively short period of time. With the increasing sophistication of DNA analysis and additional archeological discoveries, it's possible to speculate that we all spring from an extremely small group of humans.
In fact, time seems to compress with every new discovery. The common ancestor of all humans and chimps might have lived in Africa 5-7 million years ago; protohumans could have existed in southern Africa some 2 million years ago. "Modern" humans appeared approximately 150,000 years ago. But what ultimately went wrong?
Any objective observer would have to agree that our beginning was promising and our rise rapid. Within 30 or 40 thousand years we developed language, recognized our own mortality, and constructed a vast assortment of creation stories. Species come and go and ours had more than a little luck at the start, but after a shaky commencement it appeared we were on our way. Finally, in the last 10,000 years, we constructed human civilization, one which we proudly extol as proof of our "superiority" and special place on planet Earth.
While it wasn't until the start of the nineteenth century that we managed to accumulate one billion people, it took us only another one hundred years to get our second billion. We are now the most abundant group of mammals on the planet. Shouldn't we be exceedingly pleased with ourselves?
Stephen Jay Gould, the late paleontologist and a leading spokes-person for evolutionary theory, believed that the human brain had not changed in 100,000 years. In other words, the same mind that started the migration out of Africa, created the extraordinary cave paintings, and developed language ... are the same humans that built cities, skyscrapers, discovered a polio vaccine, and sent men to the moon. But didn't something different happen--at least in our most recent past?
Evolutionary biologists in their oftentimes arcane world will argue and debate over how natural evolution supposedly works: Are there periodic and sudden bursts of evolutionary changes? Is it "adaptive" progress? Are changes gradual and cumulative? But regardless of the esoteric debates, overall evolutionary change is slow, at least in terms we humans can understand.
But in the last several thousand years remarkable transformations have occurred. If it's not due to natural evolution, what's caused it? Gould, among others, attributes it to cultural change. Fifteen or sixteen thousand years ago we did not have urban settlements or large, well maintained agricultural plots. But a few thousand years later cities developed, a division of labor was established, language was written down, and laws were promulgated.
Unlike Darwinian evolution, cultural knowledge can be passed on from one generation to the next. One tribe may learn of a new weapon from another group. They make improvements, then someone else ventures onto a new pathway, and so forth and so forth. The invention of the wheel, for example, is clearly a milestone in cultural development. It allowed more people to travel greater distances, exchange ideas, improve the dispersal of goods and services, and revolutionize warfare. As one adaptation built on another, these changes occurred more and more frequently. Which finally brings us to the present.
Is that marvelous human brain just not able to keep up anymore, make new connections or modify the last 100,000 years? Is the species called homo sapien sapien coming to some sort of evolutionary dead end?
Cultural change is fast and deliberate, while natural evolution plods along at its own pace. Of course, it's possible a new species is forming at this very moment and will replace us someday. Among a handful of humans right now, it is conceivable that a "different" brain is slowly taking shape, the kind that can more readily discern other shades and let go of worn out beliefs. It's possible someone will stand up and start walking again. But will there be enough time?