Concept of evolution of specie is really as complex to truly understand as easy it appears to understand. No wonders myths abound. I didn’t know, for example, that evolution doesn’t favour survival of the fittest specie but of the fittest gene. Or that, evolution neither guarantees nor ensures improvement in quality of life or quality of specie. Evolution doesn’t necessarily mean increase in complexity as well, despite what appears to be the case as we human see ourselves at bottom of tree of biological evolution. Evolutionary outcomes are also not necessarily global optima for its members. In language of Prisoner's Dilemma, while best strategy to ‘cooperate’ for both, evolutionary stable strategy would be to ‘defect’ for both.
Yet, theory of evolution is invoked many a times in explaining natural behaviour of any animal. Why do giraffes have long neck? Why do turtles have hard shell? Why did birds learn to fly? Why are human omnivore? Strange markings on the fish? Sounds of whale? Speed of tiger? And so on. You can think of, might have heard about, or can imagine evolutionary reason behind all this. Sometimes theory to so stretched so as to appear force-fitted. But most of the times, experts will confidently claim that the reasons giraffes have long necks is that, by chance of genetic mutation, those who ended up with longer necks had advantage in foraging leaves from tall trees, and hence could survive longer, and are able to pass on their genes (,,). Such explanation is offered for any and every type of behaviour. I wonder, naturally.
Given enough time, if theory of evolution in current form is correct, any tiniest of difference can provide one gene higher survival than other, to the extent that other gene is no longer part of genetic pool of that specie. Given enough time, then, it seems natural that there should ultimately be only very-very few species that would prevail. If human have genetic advantage over gorilla, over time, only homo-sapiens should remain surviving specie. That’s how we are explained non-existent of pink tiger i.e. reason tiger have stripes. Yet, number and variety of species in existence has only been growing with time.
Does this mean that it’s merely matter of time? That four billion years of life on earth is insufficient for evolution of THE ONE specie? Perhaps. But what’s more important to understand if we are even moving in that direction? I don’t think so. Where lies my misunderstanding of evolution?
Edit 02/09/2011: Please read comments for discussion/clarification.