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Out of Africa, only to die … new clues on early human migration

How and when did humans colonise the globe? This question has become one of the key concerns of archaeologists, geneticists and human biologists. And now the latest archaeological discovery in Oman in…

Genetic estimates of the age of the common ancestor of non-African humans may be wrong. bruncosta

How and when did humans colonise the globe? This question has become one of the key concerns of archaeologists, geneticists and human biologists. And now the latest archaeological discovery in Oman in the Arabian Peninsula – distinctive Nubian stone tools – offers a new twist in the emerging story.

In the 19th century, Charles Darwin speculated that all humans, Homo sapiens, had a common ancestor who had lived in Africa, implying that at some point in the past humans must have spread from Africa to other land masses around the world.

But modern studies of this process were reinvigorated by genetic evidence that clearly showed that the far greater genetic diversity of humans outside Africa reflects their dispersal from a common origin in Africa.

Since that realisation, geneticists have estimated the likely antiquity of human migration out of Africa, and their analyses generally suggest humans emerged only 50,000 and 70,000 years ago.

Archaeologists have also been searching for the traces left behind by the great initial migrations of humans. This has often proved difficult, because humans were not the first hominids to leave Africa. Earlier migrations by Homo erectus, Homo heidelbergensis and others had already occurred, and these hominids had spread across the Old World, giving rise to Neanderthals in Europe, Denisovans in central Asia and the “Hobbit” (Homo floresiensis) in island Southeast Asia.

Map of Oman and the Dhofar region.

These hominids also left behind tools of stone and bones from meals and it has sometimes been hard for archaeologists to determine whether archaeological materials were created by modern humans or by earlier hominids.

For this reason, archaeological research in lands not colonised by earlier hominids provides an ideal situation for recognising the dispersal of humans. In those landscapes, we know the oldest dated archaeological objects represent the age of human migrations.

Humans travelling southeast from southern Asia arrived in the Philippines about 65,000 years ago, and they reached Australia 55,000 years ago. But when did they leave Africa?

The most recent archaeological discoveries in Oman suggest humans may have left Africa early. Writing in the technical journal PLoS One , a team lead by Jeffrey I Rose of Birmingham University has described finding sites near the southern coastline of the Arabian Peninsula. These sites contain stone artefacts called Levallois cores, which are distinctive of a manufacturing system named the “Nubian complex” known from the Sudan in northeastern Africa.

Rose and his colleagues think this is evidence of the movement of people from Africa, across the narrow Bab-el-Mandeb straits of the Red Sea and into the Arabian Peninsula. Perhaps this could have been the start of the long migration eastward, as humans colonised the coast of south Asia, then spreading to Southeastern Asia, and eventually Australia.

Rose and his team focused on the open-air site of Aybut Al Auwal, where an ancient campsite was positioned on a relic river terrace. Excavations there yielded samples that were dated to between 100,000 and 113,000 years old. This date is controversial because it is far older than the estimates for human emergence from Africa provided by genetic studies of modern humans.

How do we explain the apparent conflict between archaeological and genetic studies? Perhaps we have hard evidence that something is wrong with the genetic estimates for the age of the common ancestor of non-African humans.

If that were the case, Rose may have found the first footsteps of humans on their journey to Australia. But the humans creating his sites need not have survived to become the ancestors of modern humans. It is more likely that these sites represent a failure.

This might well be debris from a group who left Africa but who subsequently died out. Later groups of human migrants may have moved out of Africa and eventually colonised the globe.

The new evidence from Oman points to a complex story. The emergence of humans from Africa was not a simple triumphal march around the world: it was a long process of exploration and expansion, of risk and achievement.

It seems our ancestors had an evolutionary and demographic history containing failures as well as successes. The unfolding story of our origins is full of drama and is witness to loss and disappointment as much as of accomplishment.

Our colonisation of this planet truly was a long, hard journey.

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9 Comments sorted by

  1. Dale Bloom


    It appears that humans got to Australia (to become the Australia aborigine) before humans got to Europe.

    A possible explanation is that they were able to do this by using seacraft such as canoes along the coastline, and came direct from Africa to Australia and other areas such as Papua New Guinea, without taking an overland route.

    By using seacraft and travelling along the coastline, groups of humans could travel from Africa to Australia in less than 100 years, but it would take much longer to…

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  2. Peter Hiscock

    Tom Austen Brown Professor of Australian Archaeology at University of Sydney

    Hi Dale,
    You are quite right that there are some parallels between Australian Aboriginals and those in southern America, including similar appearance, but there has not been evidence of a close genetic link. DNA analyses of Native Americans are consistent with the idea that the Americas were colonized from the north, as groups left Siberia. However your idea of fast coastal dispersals is advocated by some archaeologists such as Sir Paul Mellars who is at Cambridge.

    1. Dale Bloom


      In reply to Peter Hiscock

      Hi Peter,

      Thanks for that. Recent findings of prehistoric fish hooks for deep sea fishing (dating back 50,000 years), certainly provides evidence that early humans were expert at sea travel, and expert at building seacraft. They would have had ready ability to travel along coastlines, and perhaps to cross oceans.

      After a quick review of recent work by Professor Sir Paul Mellars, it appears he also has a…

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  3. Peter Hiscock

    Tom Austen Brown Professor of Australian Archaeology at University of Sydney

    Hi again Dale,

    Yes Paul's grand theory is one of massive rapid displacement, and he described it at the recent Symposium in Tokyo :
    But a lot of researchers at the conference, including myself, think dispersals were a varied and elaborate process. His rapid replacement model might well work for Europe but it doesn't look so good in places such as China or Southeast Asia, even India, where we might have more gradual dispersals involving elaborate…

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    1. Dale Bloom


      In reply to Peter Hiscock

      Hi Peter,

      Whether it was an adaptation, or technology brought from Africa, catching deep sea fish such as Tuna with hooks and fishing line is a major feat.

      I also understand that deep sea fishing was carried out at places such as Easter Island where there is minimal inshore reef, and of course early Polynesians were quite adept at travelling long distances across the sea.

      Personally, I would not contemplate walking overland from Africa to Asia through jungles. Too many crocodile infested rivers to cross, and too many tigers waiting to eat me. I have sailed many miles, but personally I would not contemplate walking more than a few miles into jungle.

  4. rick doninger

    self employed

    Hey peter, check your email, you may find it interesting in regard to levallois technology being found in the USA despite the denial by the USA Mainstream. I have been told that if Middle paleo technology was found in the USA that "it would change everything" in regard to our currently proposed migration theories. At least that is what a well known american archy has told me. well, it has been found. Try a search of levallois in the USA or Mousterian in the USA. Interesting.

  5. Peter Hiscock

    Tom Austen Brown Professor of Australian Archaeology at University of Sydney

    Hello Rick,
    I will reply separately but for readers of the Conversation I offer this short note. There have been PhDs written on the levallois of the Americas and so arguably it is present. The question is whether levallois implies Middle Palaeolithic. The levallois technology described by Rose is said to be regionally distinctive and hence its source can be defined. However radial core technologies (of which levallois is a particular form) are widespread and need not have an association with Neanderthals or archaic Homo.

  6. David Arthur

    resistance gnome

    Gday Peter,

    Have you any comment on the suggestion that the migration out of Africa ~50-70 kya was into a population void due to the eruption of Mt Toba (Sumatra) ~78 kya?

    There have also been suggestions that European populations include Neanderthal genes, and Asian populations include Denisovan genes, presumably from Neanderthal and Denisovan descendants of earlier migrations out of Africa. This means that there were at least some survivors of Mt Toba, at least in Europe and in Asia (Siberia?) for the Denisovans.

  7. Peter Hiscock

    Tom Austen Brown Professor of Australian Archaeology at University of Sydney

    Hi David,

    Well the main comment I would make about Toba is that it is probably only a regional issue. Portions of Southeast Asia and South Asia would have been impacted severely but much of the rest of the world would not have been directly affected - though Toba was connected with a sharp and major drop in temperature which might have impacted on hominids. We really dont know the impact on dispersing hominids because the timing of the dispersal is imprecisely known. But you are right to imply…

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