The field of study called population genetics has played a critical role in the development of modern biology, helping unite Mendelian genetics and Darwinian evolution into one coherent framework. In most genetics classes, though, it typically gets plowed through in a simplified form in a single lecture. I suspect this is because it involves a lot of math, and most biologists like being in the field precisely because it’s generally possible to avoid all but the simplest math.
Nevertheless, population genetics has some critical insights to offer in the area of modern genomics, as evidenced by a paper that appeared in this week’s edition of Science. Some population geneticists have looked into the results of the search for mutations in genome data. Their conclusion: the human population explosion has led to the appearance of many new, rare mutations in the human population, and it’s throwing all the math off, which has some serious implications for medical research.
At the simplest level, population genetics can help us predict how often a mutation should be present in a specific population. Feed its equations things like the population size, how harmful or beneficial the mutation is, the typical mutation rate, and so forth, and it will spit out a nice prediction of what the final frequency of the mutation should be. It nicely demonstrates why even harmful mutations stick around at low levels in a population, even as evolution is doing its best to get rid of them.