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Issue date: 9/20/06 Section: The Voltage Gate

Media Credit: Jeremy Bruno A cladogram depicting the common ancestry of the known hominids. Cladograms are basically family trees showing the evolutionary history of certain organisms.

Don't you hate it when those godless liberals calling themselves "scientists" claim that we all came from apes? I mean, where the hell do they get off? It's just a theory, after all. They act like they have some sort of "peer-review" system for sifting through ideas and only accepting those ideas backed by replicable research or something.

The nerve of those guys.

This week I would like to dispel some of these common misconceptions of evolutionary theory by natural selection in the hope that we can continue with a solid foundation for understanding subsequent columns regarding modern evolution and for straight GP; people have been using these arguments for a long time.

It's just a theory, isn't it?

Yes indeed, in the same sense that gravity is a theory. A theory in the scientific sense is the most reliable of concepts, even above laws.

We're used to using the word theory as in, "I have a theory that my room smells so bad because my roommate wets the bed" or "I have a theory that if I talk tough on terror, I can get away with torture."

A scientific theory is never so arbitrary or unsubstantial. Theory is a unifying concept in science backed by decades of repeated observations and experiments.

I didn't come from a chimp.

You're right, you didn't. We share a common ancestor with chimpanzees, but we did not descend from them. That really is the key to understanding evolution.

Look at the graph accompanying this article. It's called a cladogram, which is basically a tool for biologists to trace back the family history of different organisms. This cladogram depicts the biological family tree of the hominids, also known as "the great apes."

Find "Us" on the cladogram, Homo sapiens. We are in the same bracket with the Neanderthals, meaning that we share a very recent (geologically speaking) common ancestor with the Neanderthals. If you follow the highlighted line back further, we come along a junction with Homo erectus and Homo habilis, two extinct species of upright hominids with which we share a more ancient common ancestor. Trace that highlighted line all the back to an unmarked split that branches into "Lucy" and the rest. This represents an organism that had become distinct from the other apes and had taken its first steps upright.

If you continue all the way out of those brackets, you can see how far back our common ancestor with chimps actually is. There has been a slow progression from hominids that millions of years ago looked more or less like chimps-arboreal, bent spine, etc.-through all those transitional phases (Lucy, Homo erectus), to where humans and chimps are now.

Basically, the chimp/human ancestry split very early on in hominid evolution, leading to the contemporary animals we both are now.

I don't understand how someone can believe that all life happened by accident.

First of all, one should not believe in evolution as a faith, but should accept it as a scientific theory.

Second, by no means did life progress by accident.

Your genetic code, your DNA, is incredibly complex. It provides the blueprint for every structure in your body and therefore is present in every cell, all 60,000 million of them. That takes a lot of replicating, from the time you are an embryo to point you are now, bored in Imperial Russian History.

During this replication process, errors occur called mutations. These mutations can cause physical changes within a population of animals, negative or positive, that may give the animal a handicap or a benefit in its own environment.

An example: The brown bear predates its close relative, the polar bear. These brown bears were well camouflaged and therefore well adapted to hunting in their northern forests. The climate began to cool about 250,000 years ago, and glaciers began to move into the area. Suddenly, certain populations of brown bears were no longer camouflaged; in fact, they stuck out like, well, brown bears in white snow.

Most of the bears died from starvation, but a few persisted; they were different from the others, better camouflaged because of lighter coats, more winter hardy because of thicker fur. These bears were only different because of those little errors in their genetic code that gave them a slight advantage. Now they could pass those genes on to their offspring, whose coats could become thicker and lighter. After thousands of generations, we have a completely new species: the polar bear, perfectly capable of hunting and surviving in its new environment.

So what's the catch? I just said that mutation is random, doesn't that make evolution an accident?

No. Mutation may be random, but the environmental pressures placed on species are not. If the climate never cooled and the glaciers never moved in, there would be no reason for the brown bears to change. The environment essentially selects organisms best suited to survive. This is the core principle of evolution, natural selection.

Click here to access my podcast, A Primer on Evolutionary Theory to learn more about the mechanism of evolution, natural selection.

Next: The Myth of the Mad Scientist...

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