“Out of Africa” Theory of Human Evolution Gets Further Confirmation! Saturday, May 12, 2007Posted by henry000 in Africa, anthropology, Australia, Australia Aborigines, evolution, genetics, homo erectus, human evolution, Melanesian, New Guinea, science, world.
The fascinating tale of human evolution gets another important story added to it, this time with a new DNA research done on Australian Aborigines and Melanesians from New Guinea, which further confirms the hypothesis that all humans originated from a group of people from Africa around 50,000 years ago. This is known as “Out of Africa” or the single origin theory.
Up till now the fossils and tools found in Australia have cast doubt on the Out of Africa hypothesis, since they differ significantly to South Asia. This implies that the early settlers in Australia might have interbred with the local homo erectus population that was already there (which migrated out of African some two to one million years ago), “or because there was a subsequent, secondary migration from Africa”.
But the research done using mitochondrial DNA (mtDNA) and Y chromosomes DNA shows that:
there was no evidence of a genetic inheritance from Homo erectus, indicating that the settlers did not mix and that these people therefore share the same direct ancestry as the other Eurasian peoples.
The researchers suggest that the variations in fossil and tool records can be explained with the thousands of years of isolation that the aboriginal population faced, since the land bridge joining Australia and Asia was submerged into water some 8,000 years ago.
This, in combination with an earlier report, further confirms that the Out of Africa hypothesis is becoming the firm theory of how humans have evolved. We can mainly thanks to the advancement in the science of genetics.
Below is a map of mtDNA migration, courtesy of Wikipedia:
Genes and Brains Tell the Tale of Human Evolution Tuesday, March 13, 2007Posted by henry000 in Africa, anthropology, Australopithecus, evolution, genetics, homo erectus, homo sapien, human evolution, science, world.
This wonderful article titled “Beyond Stones & Bones” provides a great summary of recent discoveries to human evolution, in particular in the area of genetics and brain science.
The great tale of human evolution is just so fascinating. A vital part of it is the use of genetics to tell the story. A delightful example provided in this article is that of using body lice to infer when human lost their body hair for good. It goes like this: body lice live in cloths, so by the time they appeared, human would have started to cover themselves with some sort of clothing, which implies loss of body hair. Now body lice is evolved from head lice (which lives in our hair), so by comparing their DNA changes, which happens at regular rate, we could calculate when human started to lose body hair for good. Using this clever technique, scientists concluded that this happened about 114,000 years ago.
Using DNA scientists have worked out that humans and chimps evolved apart around 5 to 6 millions years ago, supported by the fact that the climate became dramatically colder around that time. The recent discoveries of the HAR1 and PDYN genes shred some light on how the brain plays its part in the evolution. The HAR1 gene may “… likely helped the cortexes of our ancestors develop the elaborate folds characteristic of a complex brain”, and that the PDYN gene may have advanced brain chemistry.