Human evolution is the evolutionary process leading up to the appearance of modern humans. While it began with the last common ancestor of all life, the topic usually covers only the evolutionary history of primates, in particular the genus Homo, and the emergence of Homo sapiens as a distinct species of hominids (or great apes). The study of human evolution involves many scientific disciplines, including physical anthropology, primatology, archaeology, paleontology, ethology, linguistics, evolutionary psychology, embryology and genetics. Natural selection occurs in modern human populations. For example, the population which is at risk of the severe debilitating disease kuru has significant over-representation of an immune variant of the prion protein gene G127 V versus non-immune alleles. The frequency of this genetic variant is due to the survival of immune persons. Other reported evolutionary trends in other populations include a lengthening of the reproductive period, reduction in cholesterol levels, blood glucose and blood pressure. It has been argued that human evolution has accelerated since the development of agriculture and civilization some 10,000 years ago. It is claimed that this has resulted in substantial genetic differences between different current human populations. Lactase persistence is an example of such recent evolution. Recent human evolution seems largely however to have been confined to genetic resistance to some infectious disease, which have appeared in human populations by crossing the species barrier from domesticated animals. Without a selection pressure or opportunity for speciation, such as geographic isolation, recent human evolution has been predominantly subject to genetic drift. A more widely accepted view on human evolution is this that it has either slowed down or stopped completely in most humans. Strangely, since 11 May 2014, there has been a new human evolution development that had never been discussed even by Charles Darwin..........
Posted on: Wed, 03 Sep 2014 06:04:49 +0000
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