Humans: Evolved and Evolving
presented in association with The Genetics Society and The Milner Centre for Evolution
with
Robin Ince, Chris Stringer, Becky Wragg Sykes & Aida Andrés
Premieres on July 29th
Over millions of years Humans have evolved into becoming quite the dominant species on the planet. So, how did we get to now? What have we come from and how are we still evolving as a species? And what changes can we expect in the future in terms of diet, life span and population?
Robin Ince is joined by three experts in the field. Professor Chris Stringer is an anthropologist and Research Leader in Human Evolution at the Natural History Museum in London. Dr Becky Wragg Sykes is an archaeologist, writer and expert in Neanderthals. And Dr Aida Andres Moran is an Associate Professor in Genetics, Evolution & Environment at University College London.
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Chris Stringer when asked by Robin Ince “How much did our understanding of genetics change the position of evolution by natural selection”, did not mention what was by far the most fundamental contribution of genetics.
Darwin, as did his half-cousin Francis Galton and nearly everyone else at the time, believed in blending inheritance. That meant that a variation appearing in an individual would be diluted by half in each succeeding generation–soon being so weak in its effect as to be unrecognizable above phenotypic noise by natural selection.
Darwin’s hypothesis of pangenesis got around the problem of dilution by invoking inheritance of acquired characteristics, but without calling it that. Then,for example, if a large proportion of a population engaged in the same activity or ceased engaging in what had been a common activity (Darwins’ idea of use/disuse) a large proportion of the population would inherit the associated characteristic and dilution would therefore not be great.
Darwin wrote only that his pangenesis proposal was meant to bring together a great amount of information under one hypothesis, not to get around the blending problem. (A problem of which he was well aware, if only because it had been brought to his attention by Fleming Jenkin),
It is hard to believe that in all the years from his first unpublished formulation of his pangenesis hypothesis to the end of his life that Darwin never considered pangenesis, with its postulated inheritance of acquired characteristics, as a solution of the blending problem. In all of this, Darwin never mentions the close similarity of pangenesis to Lamarck’s ideas about inheritance.
Although only Darwin and Wallace had and clearly advanced the idea of natural selection as the driver of evolution, admiration of Darwin should not be allowed to obscure the great weakness in Darwin’s Theory of Natural Selection.
It was Mendel who first clearly showed that there are heritable characters that do not blend but reappar unchanged in the progeny of hybrids.
It could be said that Mendel rescued Darwinism.
Matthew Meselson
Harvard University