Copyright @ 1997
There is lots of controversy about Evolution and especially human evolution. It seems that even among those who accept that evolution is a force that effects humans, it is widely believed that it only effected them in the past.
Researchers blithely like to say that the mutation rate is so low that only a couple of mutations occur every thousand years. They extend this to imply that to mean that humans can only evolve very slowly and certainly not in any human or social time frame. This is extremely misleading. Evolution is not about mutations and not even really dependent on them in the short run (say 100,000 years). Biological evolution in a species is simply defined as a change in gene frequency. The frequency of any gene in a population can change quite independently of whether there are any mutations or not. In the long run, evolution is dependent on mutations to create new genes, but it is selection on those genes that cause evolution.
Humans have been making changes from one ecology to another for the last few million years. These changes have included the long slow changes in geology and climate of the human habitat, but more importantly for humans have been the changes related to human development.
Darwin mentioned sexual selection and it is basically the concept that some adaptations of a specie are not in response to external features of the ecology, but more in response to demands posed by ones own specie.
In many species, this has demanded that the males develop traits that allow them to compete with other males for females. The traits have minimal use when dealing with any part of their environment other than their own specie.
While humans have responded to changes in the external environment, bipedalism may be a good example of this, the greatest changes were in response to forces of the society or species. This is especially true recently, say the last 20,000 years.
The best example of this might be speech. It required complex physical and mental adaptations to allow for speech, but once it existed, there was terrific pressure in society to select for the ability. All traits that contributed to speech were selected for.
Some of the things that were obviously selected for in a human society would include beauty, speech, bipedalism, dexterity, etc. Intelligence would also be highly selected for as well, because intelligence is mostly defined as the skills that allow one to operate well in a society.
There are other things less obvious that would be selected for as well. City dwellers need a greater tolerance for density and a greater resistance to disease. Another way of describing some traits that would be in this category would be to list the traits useful to the various castes. This issue is discussed later on.
So back to the original issue, relative gene frequency can change extremely quickly regardless of mutation rate. Considering human history, the extent of human hybridization and the incredible selection pressures from both the changing environment and society, it seems that there has undoubtedly been recent significant changes in relative gene frequencies in humans. Humans have evolved greatly in the recent past, especially in the time of the cities.