Saturday, October 19, 2013

The Dmanisi Skull

UK Guardian (Link)

The UK Guardian does its usual great job on science coverage, here detailing the initial findings and implications of the Dmanisi Skull publication, which came out yesterday.

2 comments:

  1. To me this conclusion regarding the Georgian fossils should permanently change everyone's belief about our evolution. You may find this extract from my essay a friend put up in 2009:

    "Caucasus Population

    In the last few years fossils of half a dozen individuals, probably also ancestral to humans and dating to the time of Homo habilis (nearly two million years) have been found outside Africa. They lived just south of the Caucasus Mountains in Georgia and are associated with the same Oldowan stone technology. Like all other species on the human line mentioned so far they demonstrate a surprising level of variability (Gore 2002). In this case there seems to be no doubt they were members of a single species though. The region was probably at a geographic extremity of the total population distribution at the time, a point on their star. Their presence suggests Homo erectus ,as narrowly defined these days, may actually have evolved in Asia. From a species such as Homo rudolfensis or Homo habilis that had earlier moved out of Africa.

    Some members of this Homo erectus proper then wandered back into Africa where another species Homo ergaster had evolved independently from an Australopithecus of some sort (Wade 2001). I suggest that there they mixed (gene flow again) and members of the hybrid population invented a new Stone Age technology, the “Acheulean”. Then some of them moved back out. The wave theory of genetic, cultural and technological evolution is simple isn’t it?

    If we disregard the line that led to the Paranthropus species we find that over time there is on average an overall general decrease in the size of the cheek teeth, an increase in brain size and gradual elimination of extreme physical variations as we move from as far back as Australopithecus afarensis to modern Homo sapiens. It is actually very difficult to define precise boundaries between species and to separate them. Many fossil skulls of Australopithecus africanus, Homo habilis, Homo erectus or several other named species or even some Paranthropus skulls are difficult to assign to a particular species. And there is often disagreement as to which particular species it is. In fact I sometimes think many splitters would like to put each fossil found into a separate species.

    Lumpers regard all these different species as being just regional variants of Homo erectus. To and fro movement of genes goes back a long way in the process of our becoming human. Homo erectus may have been well named."

    I note from John Hawks' blog that he actually includes 'Paranthropus' in the 'single species,so that is interesting.

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  2. Hi Terry,

    Thanks for this short history on the discussion within the scientific community in the last few years.

    It looks like the various international teams looking at the Dmanisi skulls have been trying to come to consensus as to how to classify the skulls. In the end, they've decided on Homo erectus, indicated that Dmanisi is closely related to Homo erectus in Northern African, and even gone so far as to say that in both Africa and Dmanisi, all of these differently classified skulls may, in the end, fall into Homo erectus.

    It will be interesting to see how this plays out.

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