Human intelligence – Just a mere 2 million years in evolution?

The real thing (and also many, many, many other things, but that’s not my point right now) that truly separate humans from other species is our intelligence. Compared to any other known species on the Earth, human skull, or more appropriate, human brain to body ratio is abnormally high. No other creatures have the brain capacity that is analogous to humans. What could have caused this?

While having breakfast today, this question popped out in my head, followed very closely by this hypothesis that I have thought up. Could this large ratio (let’s call it an abnormality, at least in evolution terms) be caused by racism?

The issue of racism could very well have begun after the genus Homo (where humans are grouped as) began to diverge into different species (of which the current dominant ones are the species sapiens). As all the different species of humans began to grow, territory became scarce. A tribal war could have ensued, where the weaker species were totally eliminated, leaving a few behind. This competition could have dragged on, until enmity grew into grudge. Tribes of one species could have forbidden communications with those of other human species, and the younger generations were taught to hate the others, in other words, difference.

With a twist of chance (not fate), only one species is left. But this is not the Homo sapiens, not yet anyway. This species soon re-spread their influence over the world (if you believe the hypothesis of all humans began in Africa), and the further they get from homeland, the less likely they return, and soon made permanent settlement. Due to geography, adaptations were made and this species began to evolve races to match their environment.

Then, isolation followed by closely. Continents could have shifted (this, I’m not sure), cutting of any possible contact.

Now, since this species were taught to hate difference, and if one race comes into contact with the other, they would normally shun them. Breeding with the other races could be forbidden. Only interbreeding is allowed. This soon took a toll on the humans’ gene pool.

I have observed that the higher the class of animals, i.e. the more pairs of chromosomes they have, the easier it is for their genes to be spoiled when pure or close-to-pure breeding is employed. In other words, animals of the lower life forms do not suffer damage to their genes even if they were to perform incest, yet pedigree dogs, which are breed through pure breeding with close relatives, suffer a multitude of abnormalities.

Since humans have the most pairs of chromosomes (I think), this interbreeding could cause the genes to be damaged in as little as the next 3 generations. Most abnormalities are fatal, yet maybe some are beneficial (it must be understood that abnormalities does not equal to bad, it just means out of the norm). Beneficial like the abnormally large brain/body ratio. Some could be too large for the body to support, but eventually, a compromise is reached to the current form, after much destruction to the human genes.

So, what do you think?