Daniel L. answered • 10/18/19
UC Berkeley Molecular Toxicology graduate, 4th year medical student
This is a very fascinating question.
Remember that evolutionary processes occur over the span of tens of thousands of years. Homo sapiens as a species emerged over 300,000 years ago, so it is safe to assume that there has been genetic drift since that time.
Probably one of the most obvious phenotypic traits that has arisen recently is the persistence of gut-lactase after childhood, which is related to the recent domestication of animals and consumption of animal milk past childhood. This can be viewed as an adaptive epigenetic change to new ecological pressures.
On the other hand, natural selection is present in our population and in medicine often in surprising ways. Everybody quotes the prominence of sickle cell trait in African populations due to the selective pressures of malaria. However, did you know that recent discovery of an alternative cholesterol lowering therapy was due to the observation of a group of individuals within the African community that had remarkably low cholesterol levels? After studying that population, they discovered that a nonsense mutation in gene PCSK9 was associated with the low cholesterol levels. Flash forward 15 years and we now have a new class of lipid-lowering agents for people who cannot tolerate statins. Maybe this group of individuals is an example of positive selection currently at play?
I believe that humans will continue to evolve, maybe at a rate that is imperceptible in our lifetimes. There will be new novel mutations which will confer a survival advantage such as the case of the population with the PCSK9 mutations, who have overall lower cardiovascular risks (remember that cardiovascular disease is still the number 1 cause of death in America). Thus these genes will be passed to future generations and will result in an allelic shift within our collective population (referred as microevolution)
Hope this was useful,
Daniel
