Australia: The Land Where Time Began
The field of human biology, specifically that of hominid evolution, is a complex and rapidly changing area. There are differing views on each question, but I have found the most clearly argued cases with Stephen Oppenheimer’s book, “Out of Eden”, from where the following extracts are taken.
Genetic findings support the case that all non-Africans share one ancestral origin. Thus, the ancestors of aboriginal Australians, Europeans, Indians and Chinese all have the one date of exit from Africa. By looking at the mitochondrial DNA and Y-chromosomes of anyone outside of Africa, their single branch on the “Out of Africa” family tree can be found.
Australian aboriginals are related to Europeans and share a common ancestor just after the exodus from Africa, to the Yemen over 70 000 years ago. Thereafter, they moved progressively around the coastline of the Indian Ocean, eventually island-hopping across Indonesia to Australia where, in complete isolation, they developed their own unique and complex artistic styles.
The earliest generally accepted archaeological evidence of modern human colonization outside Africa has, until recently been Australian. Previously the oldest evidence for the colonization of the Australian continent has indicated a date of around 40 000 years ago. However, the advent of a new dating method, known as luminescence dating of silica, has revealed even older dates.
In 1990, dates of between 50 000 and 60 000 years ago were reported for the first occupation of a rock shelter on the coast of Arnhem Land, in Northern Australia. Arnhem Land is directly opposite Timor, which is the nearest island of the Indonesian Archipelago, and thus the most likely casting off point for the first Australians.
Most recent ‘Out of Africa’ syntheses argue for at least one northern exit out of Africa to Europe, and further to the rest of Asia within the past 50 000 years, while acknowledging the possibility of an earlier southern route to Australia.
The problems with the northern route for the ancestors of Australian Aboriginals is that if the exodus had left Africa any later than 115 000 years ago, there were significant barriers in place to restrict movement from the Levant to the rest of Asia. These included major mountain and desert barriers preventing travel north, eat or south from the Levant. To the north and east were the great Zagros-Taurus mountain ranges which combines with the Syrian and Arabian deserts to separate the Levant from Eastern Europe in the north and the Indian sub-continent in the South. Under normal glacial conditions, this was an impassable mountainous desert. There was no easy way around to the north because of the Caspian Sea and the Caucasus.
As in Marco Polo’s time the alternative overland route from the Eastern Mediterranean to Southeast Asia was to get to the Indian Ocean as soon as possible and then follow the coast round. To the south and east of the Levant, however, are the Syrian and Arabian Deserts, and the only option was thus to follow the Tigris Valley round from Turkey and down the western border of the Zagros Range to the Arabian Golf. But this route, through the fertile crescent, was also extreme desert outside interglacial periods and was therefore closed.
The practical impossibility of modern humans getting from the Levant or Egypt to Southeast Asia 55 000- 90 000 years ago means that a northern exodus from Africa during that period could have given rise only to Europeans and Levantines, not to Southeast Asians or Australians.
The Southern Route:
In order for the Southern route to become a viable option, several things needed to happen. The first was sea levels needed to drop. During an ice age, the sea level falls significantly, due to huge amounts of water being trapped in glaciers. The falling sea level allowed for humans from Africa to cross the mouth of the Red Sea, using rafts to island hop in some instances. Crossing from Africa, they could then move into India following the coastline. Continuing along the coast, early humans likely found their way down into Indonesia within 10 000 years. Low sea levels at this time allowed a dry walk from Aden to the tip of Java.
While recent archaeological finds have suggested human occupation dates as old as 62 000 years ago, sea levels between Timor and Australia were at their lowest some 3 000 years earlier. Thus it is more probable that the first humans crossed into Australia some 65 000 years ago. The original landing site would now be submerged beneath the sea, as it would have been on the continental shelf that was dry land about the time of the first arrivals.
WLH-50 and the complete replacement by out of Africa theory
The calvarium of WLH-50 has been used in a study to test the recent African origin theory, that suggests the complete replacement of the archaic forms, known as Homo erectus, so that H. erectus did not contribute to the ancestry of modern Australasians. They compared data for WLH-50 and 3 potential contributors to the ancestry of WLH-50 (Ngandong, Late Pleistocene Africans, Levant hominids from Skhul and Qafzeh) concluding that the results unambiguously refute the complete replacement of these potential contributors to the ancestry of the Australasians, suggesting that the Ngandong hominids should be reclassified as Home sapiens, Hawks et al., (2000). (21)
Not all agree with Hawks et al. Brauer, Collard and Stringer criticise the methods of Hawks et al., not accepting that their study disproves the Out of Africa hypothesis that requires the complete replacement of earlier populations.
In the recent BBC documentary, Human Journey, based on the Out of Africa hypothesis, the very African appearance of the Andaman Island people of the present, and the reconstruction of a skull from India to reveal an African appearance, is presented as evidence of the migration from Africa 70,000 years ago. Is it possible the African migrants passed from Africa, through Indonesia to Australia in the last 70,000 years, and by 60,000 years ago looked like Australian Aborigines, without mixing with populations that already looked similar to the ancestral Aborigines, as the earlier population of Indonesia did. And the sites that have been dated to 60,000 years are on the present day dry land, not on the continental shelf where the migrants would have landed when they arrived on the last leg of their island-hopping journey, presumably the landing would have occurred some time before 60,000 years ago. After they landed, did they live near the sea they knew for a while before spreading to the interior that is now the coast, or sprint inland to the sites that have now been dated, that at that time was populated with some very large and dangerous animals they weren't familiar with. They were also faced with a completely different potential food plants they had to learn about.
There is also the wide diversity of physical types, especially among the people from the earliest known sites. I would think that would be more consistent with non-homogeneous inheritance, rather than with a small group of ancestors that came from the same place and presumably looked at least a bit similar to each other.
|Author: M.H.Monroe Email: email@example.com Sources & Further reading|