Science and Technology : Re-Thinking the Out of African Theory

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  1. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    "Out of Africa" theory may need a rewrite

    (Livescience.com)

    Newfound stone artifacts suggest humankind left Africa traveling through the Arabian Peninsula instead of hugging its coasts, as long thought, researchers say.

    Modern humans first arose about 200,000 years ago in Africa. When and how our lineage then dispersed has long proven controversial, but geneticists have suggested this exodus started between 40,000 and 70,000 years ago. The currently accepted theory is that the exodus from Africa traced Arabia's shores, rather than passing through its now-arid interior.
    However, stone artifacts at least 100,000 years old from the Arabian Desert, revealed in January 2011, hinted that modern humans might have begun our march across the globe earlier than once suspected.
    Now, more-than-100 newly discovered sites in the Sultanate of Oman apparently confirm that modern humans left Africa through Arabia long before genetic evidence suggests. Oddly, these sites are located far inland, away from the coasts.
    "After a decade of searching in southern Arabia for some clue that might help us understand early human expansion, at long last we've found the smoking gun of their exit from Africa," said lead researcher Jeffrey Rose, a paleolithic archaeologist at the University of Birmingham in England. "What makes this so exciting is that the answer is a scenario almost never considered."

    http://www.cbsnews.com/8301-205_162-57334287/out-of-africa-theory-may-need-a-rewrite/
     
  2. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    Arabian artifacts
    The international team of archaeologists and geologists made their discovery in the Dhofar Mountains of southern Oman, nestled in the southeastern corner of the Arabian Peninsula.
    "The coastal expansion hypothesis looks reasonable on paper, but there is simply no archaeological evidence to back it up," said researcher Anthony Marks of Southern Methodist University, referring to the fact that an exodus by the coast, where one has access to resources such as seafood, might make more sense than tramping across the desert..
    On the last day of the research team's 2010 field season, the scientists went to the final place on their list, a site on a hot, windy, dry plateau near a river channel that was strewn with stone artifacts. Such artifacts are common in Arabia, but until now the ones seen were usually relatively young in age. Upon closer examination, Rose recalled asking, "Oh my God, these are Nubians — what the heck are these doing here?"
    The 100-to-200 artifacts they found there were of a style dubbed Nubian Middle Stone Age, well-known throughout the Nile Valley, where they date back about 74,000-to-128,000 years. Scientists think ancient craftsmen would have shaped the artifacts by striking flakes off flint, leading to distinctive triangular pieces. This is the first time such artifacts have been found outside of Africa.
    Subsequent field work turned up dozens of sites with similar artifacts. Using a technique known as optically stimulated luminescence dating, which measures the minute amount of light long-buried objects can emit, to see how long they have been interred, the researchers estimate the artifacts are about 106,000 years old, exactly what one might expect from Nubian Middle Stone Age artifacts and far earlier than conventional dates for the exodus from Africa.
    "It's all just incredibly exciting," Rose said.
     
  3. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    "The 100-to-200 artifacts they found there were of a style dubbed Nubian Middle Stone Age, well-known throughout the Nile Valley, where they date back about 74,000-to-128,000 years. Scientists think ancient craftsmen would have shaped the artifacts by striking flakes off flint, leading to distinctive triangular pieces. This is the first time such artifacts have been found outside of Africa."
     
  4. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    Origins of Modern Humans: Multiregional or Out of Africa?

    Donald Johanson

    The origin of modern humans: 1) they arose in one place — Africa and 2) pre-modern humans migrated from Africa to become modern humans in other parts of the world. Most evidence points to the first theory because:


    • fossils of modern-like humans are found in Africa
    • stone tools and other artifacts support African origin
    • DNA studies suggest a founding population in Africa
    One of the most hotly debated issues in paleoanthropology (the study of human origins) focuses on the origins of modern humans, Homo sapiens.9,10,3,6,13,15,14 Roughly 100,000 years ago, the Old World was occupied by a morphologically diverse group of hominids. In Africa and the Middle East there was Homo sapiens; in Asia, Homo erectus; and in Europe, Homo neanderthalensis. However, by 30,000 years ago this taxonomic diversity vanished and humans everywhere had evolved into the anatomically and behaviorally modern form. The nature of this transformation is the focus of great deliberation between two schools of thought: one that stresses multiregional continuity and the other that suggests a single origin for modern humans.
    Understanding the issue

    Multiregional theory: homo erectus left Africa 2 mya to become homo sapiens in different parts of the world.
    The Multiregional Continuity Model15 contends that after Homo erectus left Africa and dispersed into other portions of the Old World, regional populations slowly evolved into modern humans. This model contains the following components:
    • some level of gene flow between geographically separated populations prevented speciation, after the dispersal
    • all living humans derive from the species Homo erectus that left Africa nearly two million-years-ago
    • natural selection in regional populations, ever since their original dispersal, is responsible for the regional variants (sometimes called races) we see today
    • the emergence of Homo sapiens was not restricted to any one area, but was a phenomenon that occurred throughout the entire geographic range where humans lived.
    http://www.actionbioscience.org/evolution/johanson.html
     
  5. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    X-woman’ challenges out of Africa theory
    25 March 2010

    by Richard Ingham

    Agence France-Presse


    DNA from a previously unknown hominid found in Siberia, some 40,000 years old, could rewrite the textbooks - and represent a new branch on the human family tree.

    DNA from a female of previously unknown hominid – dubbed the X-woman – lived in southern Siberia some 40,000 years ago and could be a new branch on the human family tree, a finding that would rewrite Homo's exodus from Africa.
    In a technical feat, scientists sequenced DNA from the bone fragment of a pinkie finger, possibly from a small female child, found in a cave in the Altai Mountains.
    The bone found in Denisova Cave was extricated in 2008 from a soil layer carbon-dated to between 30,000 to 48,000 years ago.
    Teased from a cellular component called mitochondria, the genome was compared to the code of our extinct cousins the Neanderthals, Homo sapiens, the bonobo and chimpanzee.
    The Siberian hominid, the investigation found, had some 400 genetic differences, which makes it a candidate for being a distinct species of Homo, as the genus for humans and closely related primates is known.
    It, us and the Neanderthals all shared a common ancestor who lived around a million years ago, say the investigators.

    http://www.cosmosmagazine.com/features/online/3366/‘x-woman’-triggers-rethink-out-africa-theory
     
  6. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    Australia Challenges Out-of-Africa Theory


    [​IMG]


    Australian scientists said today they had analyzed the oldest DNA ever taken from human remains, and that the results challenge the theory that modern humans evolved from African ancestors alone.
    Researchers at Australian National University said they had analyzed DNA taken from remains unearthed in 1974 at Lake Mungo in the state of New South Wales. Dating in May 1999 put the age of the skeletal remains at between 56,000 and 68,000 years old.
    ANU anthropologist Alan Thorne said that neither “Mungo Man’s” completely modern skeleton nor its DNA had any links with human ancestors from Africa found in other parts of the world.
    “Neither of them [the skeleton or DNA] show any evidence that they ever were in Africa,” Thorne told Reuters. “There’s modern humans in Australia that have nothing to do with Africa at all.”
    The findings, revealed in The Australian newspaper today, challenge the prevailing “out of Africa” theory of evolution because “Mungo Man” has a genetic line which has vanished yet his skeleton is completely modern.
    The “out of Africa” theory holds that modern humans evolved from a common homo erectus ancestor in Africa.
    Homo sapiens then left Africa and spread across the world between 150,000 and 100,000 years ago.

    The ANU researchers say that because Mungo Man is modern anatomically, yet has a vanished DNA line, it means at least one group of homo erectus’ descendants evolved outside of Africa.

    http://abcnews.go.com/Technology/story?id=99257&page=1
     
  7. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    "Thorne said the dating of Mungo Man meant there was no doubt that ancestors of Australia’s Aborigines came to the continent from Asia about 70,000 years ago — some 30,000 years earlier than was thought."
     
  8. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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  9. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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    14 December 2011

    'Out of Africa' theory pushed back over 40,000 years
    Until now, geneticists and archaeologists had believed that modern man has started to migrate out of the cradle of civilisation in Africa between 70,000 and 40,000 years ago. But new discoveries in the southern region of the Sultanate of Oman are causing a re-evaluation.
    An international team, under the auspices of the Omani Ministry of heritage and Culture, and led by Dr Jeffrey rose of the University of Birmingham (UK) has been researching in the Dhofar mountains in southern Oman, near the border with Yemen. They have discovered a plethora of sites attributed to 'Nubian Middle Stone Age', which produced highly distinctive stone tools. Until these finds they had only been found in Africa.
    The date of the artefacts and the sites has been confirmed by the use of a technique known as Optically Stimulated Luminescence (OSL). This measures doses from ionizing radiation that the material in question has absorbed and it effectively calculates when the object was last exposed to sunlight.
    The results have pushed the migration out of Africa back to approximately 106,000 years ago and refocused attention on a migration path through the Arabian peninsula rather than Europe. The dating coincides with a period when the Arabian peninsula comprised sprawling grasslands, before the Last Ice Age and Dr Rose is quoted as saying "For a while South Arabia became a verdant paradise rich in resources - large game, plentiful fresh water, and high quality flint with which to make stone tools".

    http://www.stonepages.com/news/archives/004642.html
     
  10. Omowale Jabali

    Omowale Jabali The Cosmic Journeyman PREMIUM MEMBER

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