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Thread: Was a lost lake needed for "out of Africa?"

  1. #1 Was a lost lake needed for "out of Africa?" 
    Forum Radioactive Isotope skeptic's Avatar
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    Taken from New Scientist 25 January 2014 page 11

    A dried up lake has been found in Egypt, in the desert. It dried up more than 70,000 years ago, but would have been massive in its heyday. Such a body of water would likely have supported a large population of early humans, hunting the rich game, and collecting fish and other lake life for food.

    The ancestors of modern Europeans left Africa about that time. Maybe the lake was the necessary way station, and stimulus for humans to be in a geographic position poised to leave Africa??? Could the drying of the lake have been the push that sent humans on their millennia long quest for new homes?


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    70000. Sounds like it's too recent for the people who became indigenous Australians to have made their first move out of Africa. When you look at evidence in Australia, it's entirely possible people were here 50000ish years ago.

    OTOH, we can be pretty certain that local climate / river / lake changes would have driven lots and lots of movement of various groups at various times. "Out of Africa" would be the cumulative effects of several such events. Once again, I'd say 70000 years doesn't give enough time for, as an example, movement and establishment of population centres on the Chinese coast. I realise that probably most of the longest single moves would have been by travel in river and/or seagoing craft - or by walking during colder conditions when the sea level dropped enough for there to be easily negotiated land bridges between islands and continents that are now separated by sea. Much as the moves across the Pacific to previously uninhabited islands took only a couple of thousand years were achieved by seagoing craft- and that fairly recently.


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    Forum Radioactive Isotope skeptic's Avatar
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    Anthropologists believe there were two "out of Africa" movements. One about 100,000 years ago, leading to human remains in Israel dated to that time. And a later, and greater movement of a bit more than 70,000 years ago, which led to humans in Europe. The oldest human remains in Australia were a little over 40,000 years old by carb on dating, but the first humans arrived (probably) some time between 40,000 and 60,000 years ago, which leaves plenty of wriggle room for this theory.
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    Forum Professor pyoko's Avatar
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    I believe in what genetics say. In this, a must-see for anyone interested in where we came from and how we moved. It also answers how and when Australian natives got there:

    It is by will alone I set my mind in motion.
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by skeptic View Post
    Anthropologists believe there were two "out of Africa" movements.
    Something I read the other day (and I have no idea where so I can't check it) suggested that there is now evidence that there may have been many, and in fact was an almost continuous process (with, of course, some number of more significant migrations).
    Halliday likes this.
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    The lake might have been needed. It would indicate a reduction in people leaving Africa if it was.
    Since most of the major migrations had happened before 70,000 years BP it is an attractive hypothesis and links nicely with the idea of the Toba population bottleneck.
    Population Bottlenecks and Pleistocene Human Evolution
    Mount Toba : Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans
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    Universal Mind John Galt's Avatar
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by skeptic View Post
    Anthropologists believe there were two "out of Africa" movements.
    Something I read the other day (and I have no idea where so I can't check it) suggested that there is now evidence that there may have been many, and in fact was an almost continuous process (with, of course, some number of more significant migrations).
    This is logical. Otherwise we have to identify a mechanism that stops migration. Some events may have encouraged movements, others would have discouraged it, but some movement would surely be likely. Also, it would be foolish to assume that the movement was always outwards from Africa. Periodically some of it must have been in the other direction. Will we ever be able to characterize that? I would expect so, though not for some time. (Some time = 10 to 50 years)
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    Some 12,000 years ago, the only place to live along the eastern Sahara Desert was the Nile Valley. Being so crowded, prime real estate in the Nile Valley was difficult to come by. Disputes over land were often settled with the fist, as evidenced by the cemetery of Jebel Sahaba where many of the buried individuals had died a violent death.

    But around 10,500 years ago, a sudden burst of monsoon rains over the vast desert transformed the region into habitable land.

    This opened the door for humans to move into the area, as evidenced by the researcher's 500 new radiocarbon dates of human and animal remains from more than 150 excavation sites.

    "The climate change at [10,500 years ago] which turned most of the [3.8 million square mile] large Sahara into a savannah-type environment happened within a few hundred years only, certainly within less than 500 years," said study team member Stefan Kroepelin of the University of Cologne in Germany.

    Frolicking in pools

    In the Egyptian Sahara, semi-arid conditions allowed for grasses and shrubs to grow, with some trees sprouting in valleys and near groundwater sources. The vegetation and small, episodic rain pools enticed animals well adapted to dry conditions, such as giraffes, to enter the area as well.

    Humans also frolicked in the rain pools, as depicted in rock art from Southwest Egypt.

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