The Impact of Modern Medicine on Human Evolution

Medicine is a scientific practice that affects human evolution by contributing to the human niche construction. It is a science which deals with material substrates of disease, from organs to DNA, and environmental threats, such as germs and chemicals, and tries to modify those elements that are also factors of natural selection. However, eugenics concerns are not sustainable, since there is no reason to think that natural selection might be eliminated among humans because of medicine. There is still plenty of individual variation in reproductive success in modern human populations - part of this variation being indirectly promoted by medical practice - but not always detrimental to fitness. On the one hand, medicine can directly act upon genetic frequencies, with genetic screening, genetic therapies, in vitro fertilization, and selective abortion. On the other hand, it can affect evolution by changing human behavior and human environment. The hospital, in particular, is a new "niche" expressly designed for the cure of diseases. This new environment has been fundamental in decreasing the mortality rate of human populations and in expanding our life expectancy. At the same time, it favors the emergence of resistant strain of bacteria. Given that medicine is deeply related to human evolution, medical sciences should be very well informed about the evolutionary theory and evolutionary processes. Evolutionary biology can be crucial in disease control, and therefore it may have an important role to play in the design of medical intervention. All the arguments here outlined give enough evidence to support the development of evolutionary medicine and its use as a basic science for medical sciences.