All modern human originated in sub-Saharan Africa, according to a new study boasted by its founders as the "final blow" against an opposing viewpoint. Not so fast, says one anthropologist who finds flaws in the evidence.
The new study, published in the July 19 issue of the journal Nature, delivers what the researchers say could be the final verdict in support of the single point "Out of Africa" theory.
Manica and colleagues took multiple measurements of more than 4,500 male fossil skulls from 105 populations around the globe. They combined the results with data from studies of global genetic variations in humans, finding that both genetic and skull variability decreased with distance from Africa. So populations in southeastern Africa held the highest variability compared with populations in other countries.
The results held even when the scientists accounted for climate, since climate conditions can lead to changes in skull features. " In very cold climates you tend to generate a slightly thicker brow ridge. Whether or not that’ s to keep horrible blizzards out of your eyes, I don’ t know, " Amos said.
Past studies based on skull morphology have been weak and have supported both of the humanorigin views.
In his own research, Hawks is funding that natural selection has led to changes in thousands of genes during only the past few thousand years.
"I’ m really thinking just the opposite of this paper, " Hawks said. "There are differences in the skull between populations, including their variability, but it is mostly due to very recent effects and not the origin of modern humans. "
"The muhiregional idea is identical to the recent African origin idea, except for its prediction that Europeans and Asians were part of the single population of origin and didn’t become extinct. "
[A] "Humans seem to have poured out of Africa, spread out across the world, but at a really quite uniform rate such that you get this lovely gradual loss of diversity," said study team member William Amos of the University of Cambridge.
[B] All modern humans originated from the same ancestors and they kept evolving as the society advances. Some species died out but others remained to live on the earth, which is still impossible to solve.
[C] At the end of the day, a resolution to the " Out of Africa" debate may be impossible, he said. Most of the evidence can be interpreted as supporting both human-origins theories. "It’ s really hard to find the two," Hawks said.
[D] This study " adds a p line of evidence to the Out of Africa (hypothesis) using such morphology," said paleontologist Will Harcourt-Smith of the American Museum of Natural History in New York. Harcourt-Smith was not involved in the current research.
[E] Debate over the origins of modern humans has simmered among anthropologists for years, with one theory asserting that Homo sapiens migrated across the world from a single point in Africa. The other theory states that multiple populations of Homo sapiens independently evolved from Homo erectus in regions beyond Africa.
[F] The recent study was funded by the Biotechnology and Biological Sciences Research Council. It has provided conclusive evidence concerning the actual process of human evolution.
[G] "We have combined our genetic data with new measurements of a large sample of skulls to show definitely that modern humans originated from a single area in sub-Saharan Africa," said lead researcher Andrea Manica of the University of Cambridge.
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