What does population size tell us about evolution?
The size of the human population is interesting, because until recently it was very small. It exploded recently. Over the last few hundred years, it’s simply gone through the roof. So we think of course of humans now as having an enormous population, and there can’t be very much more evolution going on because the general feeling among many people is that evolution is more likely to happen in small populations than in large ones. The reason evolution might happen in small populations rather than large ones is for various reasons. First of all, chance may play a big role in a small population. You may lose certain genes, you may increase other genes in frequency in a small population. That’s more likely to happen than in a large one. Small populations are more likely to be present in rapidly changing environments, so if the environment is changing quickly and putting new selective pressures on a population, it’s likely that the population will be small because it’s surviving this rapidl
