We Are All Africans

One of the most stunning discoveries to come out of genetic research over the past 20 years is that on a strictly biological basis, the concept of "race" has no useful meaning, nor any power to explain what we are as people. 99.9% of human DNA is the same from individual to individual. Thus the broad groupings everyone has come to think of as races --Caucasians, Mongols, Negroes-- are all the same species, Homo Sapiens.

That finding has tended to give more support to the theory that humans evolved first in Africa and then spread to other parts of the world. (The other leading theory, called the multi-regional model, holds that humans evolved in several places simultaneously) Within the 0.1% of human DNA that does vary, paleontologists, anthropologists, and geneticists have been working together to sort out the issue through analysis of minute changes in mitochondrial DNA, the Y chromosome, and more recently, whole genomes. They've pieced together a road map using those three data streams that reveals the past movements of our ancestors. At the beginning of the trail is an unknown African woman who lived approximately 200,000 years ago. Everybody alive today is descended from her.

Intelligence appears to be the leading factor that made it possible for humans to expand into territories already occupied and controlled by large predators. Of the many theories that have been proposed to account for why our particular branch of hominids got so much smarter than the others, the current leader is that it was related to the climate in east Africa's greater rift valley. About 200,000 years ago this area began to oscillate between relatively wet and fertile to relatively dry and sparse.

These changes occurred over periods spanning decades, which was fast enough to keep humans from becoming too comfortable and settled but slow enough to let them acclimate. It was an environment that required more mental flexibility, more savvy about finding food and other resources, and more capacity to recognize patterns, in order to survive. Intelligence, in effect, was an adaptation that enabled early humans to occupy both niches because it wasn't specific to either of them.

Our ancestors needed every bit of this flexibility when the most recent ice age set in. Most of the world's fresh water was locked up in glaciers, leaving Africa subject to severe drought. The human population barely scratched by for roughly 140,000 years. Its numbers shrank to an estimated 2,000 individuals scattered in small groupings across the continent, isolated from each other. In fact our species almost went extinct.

About 70,000 years ago circumstances changed for the better. The Earth warmed up a little. There was a bit more water, a bit more food, and with it a bit of growth in the human population. Most important, there was a way out: a narrow pathway through the Sahara Desert opened in northeast Africa that allowed homo sapiens access to the Middle East.

The first arrived about 60,000 years ago. From then on it was a comparatively simple matter to spread out through Europe, Central Asia, East Asia, the Pacific Islands, and even the Americas. Granted, this African diaspora took over 50,000 years, in part because there were other hominids --the Neanderthals mainly-- to out-compete and displace. But over the course of more than 100,000 years surviving Africa's inhospitable climate, homo sapiens acquired several advantages their rivals lacked. They had gained a capacity to think abstractly, to make complex plans, to innovate, and most of all, to use spoken language, which tied the other three together.

My design showing the spread of humanity through the world is vastly oversimplified as drawn. In fact early peoples wandered and weaved all over. Sometimes they went north, sometimes east, sometimes west, sometimes south, wherever there was food to be found. But it is essentially correct in that once Africans got to the Middle East, it became the launching point for further perambulations to almost everywhere else on the planet. Only Antarctica didn't acquire human settlers, and only because early humans couldn't get there.

So what the Sam Hill does any of this have to do with a simple T-Shirt design? Not as much as I'd like, but only because there are too many of these major developments in human evolutionary history to represent with a simple graphic. The spread of humanity from Africa to every land mass on the globe except one will have to serve as a rough stand-in.

And I suppose I have another reason. Setting aside the biological reality mentioned above, the idea of race continues to float around among us. With it comes a second idea: that there is a relationship between race and intelligence, and that some races have more of it than others. This idea has been banished to the margins of public discourse for the most part, but occasionally it tries to elbow back into the limelight; recall the publication in 1994 of "The Bell Curve." It is necessary therefore to affirm that everything we are as a species, most especially our formidable brains, was baked and tested in Africa. The brains that populated the world, that invented agriculture, that invented animal husbandry, that invented writing, that invented metallurgy, that tamed and found myriad uses for electricity (and yes, that invented slavery and nuclear weapons too), were African. If our ancestors 4,000 - 5,000 generations ago had not been so tough and so smart, none of us would be writing content for Squidoo and none of us would be reading it. We Are All Africans.

More information is available at:
The Genographic Project

and at:
Wikipedia: human evolution




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