a system shaped over long periods of time by evolution with all kinds of trade-offs and imperfections. Understanding the evolution of the human body can help medical doctors better understand and treat various disorders. Research in evolutionary medicine suggests that diseases are prevalent because natural selection favors reproduction over health and longevity. In addition, biological evolution is slower than cultural evolution and humans evolve more slowly than pathogens. Whereas in the ancestral past, humans lived in geographically isolated communities where inbreeding was rather common, modern transportation technologies have made it much easier for people to travel great distances and facilitated further genetic mixing, giving rise to additional variations in the human gene pool. It also enables the spread of diseases worldwide, which can have an effect on human evolution. Furthermore, climate change may trigger the mass migration of not just humans but also diseases affecting humans. Besides the selection and flow of genes and alleles, another mechanism of biological evolution is epigenetics, or changes not to the DNA sequence itself, but rather the way it is expressed. Scientists already know that chronic illnesses and stress are epigenetic mechanisms. See also Blood type distribution by country Evolutionary approaches to depression Genetic genealogy Heritability of IQ Human mating strategies Missing heritability problem Race and genetics Sexual selection in humans Notes References External links Randolph M. Nesse, Carl T. Bergstrom, Peter T. Ellison, Jeffrey S. Flier, Peter Gluckman, Diddahally R. Govindaraju, Dietrich Niethammer, Gilbert S. Omenn, Robert L. Perlman, Mark D. Schwartz, Mark G. Thomas, Stephen C. Stearns, David Valle. Making evolutionary biology a basic science for medicine. Proceedings of the National Academy of Sciences. Jan 2010, 107 (suppl 1) 1800–1807. Scott Solomon. The Future of Human Evolution | What Darwin Didn't Know. The Great Courses Plus. February 24, 2019. (Video lecture, 32:19.) Laurence Hurst. Is Human Evolution Speeding Up or Slowing Down? TED-Ed. September 2020. (Video lecture, 5:25) How Humans are Shaping Our Own Evolution, National Geographic, D. T. Max, 2017 Further reading Biological anthropology Holocene Human evolution Modern human genetic history Upper Paleolithic