Freitag, 11. April 2014
On the Time Scale of Human Evolution: Evidence for Recent Adaptive Evolution
On the Time Scale of Human Evolution: Evidence for Recent Adaptive Evolution (full d.)
Gerhard Meisenberg (2008)
To what extent did the genetic constitution of human population change in the recent past, and how fast are evolutionary changes proceeding in present-day populations? This review summarizes the available evidence about genetic adaptations that evolved after the dispersal of modern humans from Africa about 50,000 years ago and especially since the Neolithic Revolution and the emergence of the first civilizations. Evidence for recent evolutionary change is obtained from the molecular study of individual genes that have been or are currently under selection, and genomic studies that identify genomic regions under recent or ongoing adaptive evolution. The molecular evidence is complemented by archaeological evidence about population dispersals and prehistoric living conditions, and by evidence from historical demography about differential fertility and mortality in historic populations. The conclusion is that evidence for recent adaptive evolution is overwhelming, in many cases at the level of individual genes. There is also evidence that in many cases the selection of adaptive traits occurred in recent historic times. These adaptations evolved in response to climatic conditions, the nutritional changes brought about by the introduction of settled farming, exposure to new diseases, and the social conditions of civilized life. There is evidence that compared to earlier times, human adaptive evolution has accelerated massively since the Neolithic Revolution, possibly by a factor of about 100. Because historic and evolutionary time scales overlap, gene-culture coevolution is emerging as a major unifying theme in anthropological research.