Doubting Didymus

In the evolutionary sense, "competition with each other" does not neccessarily imply fighting, or chasing off, or even squabbling over resources. In fact, you don't even have to meet the other guy in order to compete with them in an evolutionary context.

What intra-species competition is, when we're talking about natural selection, is the race to get your heritable material represented in the next generation more than the next feller. Not neccesarily as a result of conscious action, either: it just so happens that variant genes that encourage their own spread, or improve the overall effectiveness of the interlocked web of gene-effects, will naturally increase in frequency over those that are less effective. This means that when a trait appears that allows you to have 3 babies a year, where the next family you never met at the other side of the population distribution, frigging miles away can have only 2 a year, the first trait will be over-represented in the next generation, which means it spreads, which means that if selection is strong enough it will replace even the genes from that lot over in the east that you never laid eyes on.

It's really the genes that are doing the red-in-tooth-and-nail stuff. We organisms can get along quite peacefully while our genes do the competing.

What that means for group altruism is that it usually doesnt exist, especially when we get into such lofty cerebral concepts as species survival. We are the only species that would consider it a shame if we all died out, unless other apes have much more complex minds than I have ever heard. Natural selection wouldn't have any inclination to engender such a desire either, as the gene for species protection, A) almost certainly doesnt exist, and B) wouldn't be much of a selective advantage in terms of generation timeframes, which is what selection ticks in.

So, while its true that we humans have a tendancy to fuck everything we touch into next week, we also have an intellectual desire to not obliterate ourselves entirely. There are always the nutjobs in their concrete bunkers waiting to repopulate with the straggled survivors, or the self-seeking millionaire megalomaniacs with reinforced basements.

Peez

I think that this has already been addressed quite well, but allow me to add this example:

Imagine a population of moose living on an isolated island. There is a limited amount of food produced by plants on the island, which means that if there are too many moose the whole population might starve to death. In the moose gene pool are some genes that make moose selfish (reproduce as much and as fast as they can), and other genes that make moose behave in a way that helps the population to survive (slow down or even stop reproducing when there are too many moose for the food available). What will happen here? Natural selection will favour the selfish moose, since these moose will be passing on more genes to succeeding generations than the population-helping moose (especially as food starts to run short). Generation after generation the selfish genes become more and more common, and will eventually take over completely if the population does not go extinct first. Ultimately the population may go extinct because of this selfish behaviour, and this is what we often see happening.

It is possible for selection at the population level to influence evolution, but generally natural selection on individuals is much stronger.

Peez