On the 12th February 2009 it will be Charles Darwin's 200th birthday. As a means of celebrating the birthday of one of sciences most enlightened minds I thought I'd talk about how human evolution is no longer relevant and how we influence the evolution of other species.
Okay it might sound a little harsh to say humankind will no longer evolve, but hear me out. The theory of evolution as laid out by the great Charles Darwin demonstrates how creatures evolve based on external stimuli such as changes in the environment, or by other external forces (such as human interference). One such proof of this is what Charles Darwin observed and noted on the Galapagos Islands with the varying characteristics of the Galapagos Tortoise (Geochelone nigra) between the different islands. If you go to one island where the climate is moist there is plenty of grass and edible vegetation close to the ground - the sub-species of tortoise on these islands have flat ridges on the front of their carapaces whereas tortoises from the drier islands have to reach higher for sustenance - these ones have "saddle"-like carapaces to allow a greater head movement. It is generally accepted by all except the most devout religious people that the theory of evolution is correct, especially as humankind is find more and more evidence to support it as time passes.
However, can we assume that evolution is constant? If there are no reasons for a species to adapt, then the only evolution that is likely will be minor changes to physical appearance such as the average height and size of the species. Such external stimuli no longer exist for humankind, at least not in the manor that will promote mutations beneficial to the advancement of the human race. It is often speculated in science fiction, especially in TV shows such as Heroes that we could eventually evolve to do more such as fly, or read minds. Further evolution of our species, other than minor changes to outward appearance, I believe to be impossible. If there is something that threatens us we build technology which then "evolves" over time instead. If an animal threatens human life then we kill it or ensnare it. If we find one food source dying out (such as a species of fish) we breed more of it.
So let us now consider human evolution so far, going back to when apes first appeared. The apes first came about after the dinosaurs were more or less wiped out by an extinction level event unlike any the world had seen before - this left an opening for mammals to take centre stage, but it also brought about new predators. One type of mammal found that by going up into the trees it could escape those predators, so over many generations the characteristics from mutations that best suited them going up trees were the ones that stuck (those that didn't would have been eaten). Eventually as the landscapes changed apes would have come down out the trees with the need to cross different terrain such as streams and savannah and so over time they're spines straightened.
From this perspective I can't see how human evolution can continue without some dramatic change that we couldn't fall back on technology for - but if it was something that dramatic then there would be a fair chance we wouldn't be around afterwards anyway.
I'd be interested to see what other peoples thoughts on this topic are.
