Planet Earth

The expanding crest of modern humanity

Gene ExpressionBy Razib KhanJul 20, 2012 4:46 AM

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If you are interested in genomics and human evolution, a new review paper in PLoS Genetics is a must read, Genomic Data Reveal a Complex Making of Humans. A must read not because you need to agree with the thrust of the authors' arguments, but because it provides a thorough bibliography for the last 2 to 3 years. Here is the abstract:

In the last few years, two paradigms underlying human evolution have crumbled. Modern humans have not totally replaced previous hominins without any admixture, and the expected signatures of adaptations to new environments are surprisingly lacking at the genomic level. Here we review current evidence about archaic admixture and lack of strong selective sweeps in humans. We underline the need to properly model differential admixture in various populations to correctly reconstruct past demography. We also stress the importance of taking into account the spatial dimension of human evolution, which proceeded by a series of range expansions that could have promoted both the introgression of archaic genes and background selection.

The main problem I have at this point is the general mode of range expansions, whereby population A expands as a demographic wave across a substrate of population B. These sorts of models seem to assume a sort of continuous dynamic process. In contrast, I am beginning to suspect that much of the human demographic past was characterized by discrete events. The closer to the present the more I'm convinced of this, though honestly I am now pushing back my own timing for the origins of many of the human distinctive traits, such as culture, well before behaviorally modern humans.

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