Matt

This is a question that has come up repeatedly since Darwin's theories became well-known (it is no less valid for that). In fact, I think it has appeared in A-level papers every now and again - I seem to remember it in one of my "past papers" back in the 1980s.

One thing you must understand about evolution is that it is normally slow. Even when it is quick, it would seem slow to you or me because it takes many generations and we have only one life each. The other thing to bear in mind is that evolution exerts its influence only where there is selective pressure.

I don't want write a whole essay (and I doubt you want to read one), so I'll be brief explaining what I mean by selective pressure. In essence, if I happen to have a characteristic that gives me advantage then I am more likely to survive and pass that characteristic on to my children. Clearly, people without that advantage must be less likely to pass on their genes. In the developed world, there are not many advantages I can think of which would give me enough of an edge.. In light of those last three sentences, you ask yourself if evolution is currently being pushed by technology.

I feel it is far more likely that the evolution of mankind will be under the influence of infectious diseases, geography etc. rather than technology. If I was a betting man, I would say that humans will not be recognisably different when we go extinct. I'm a bit of a pessimist though.

"if I happen to have a characteristic that gives me advantage then I am more likely to survive and pass that characteristic on to my children. Clearly, people without that advantage must be less likely to pass on their genes."

Adding to what Pete said above, if "I" am part of a very large total population, it will take many, many more generations for my advantageous characteristic to spread through to most of my species, than it would if I were in a small population, thus any "changes" in the human species would spread slowly. We are members of an extremely large population, compared any other animal of similar body size.

The other major influence of the "speed of evolution"  is the age at which first breeding occurs and the total number of children in one lifetime and even in these respects, humans will evolve relatively slowly as we "mature" late and very seldom have more than 1 child per year, for 30 years. Some men may significantly exceed this, but the present lifetime average is a little over 1 child (who will get to breed) per person.