Refinements of the 'Out of Africa' theory
Friday March 29, 2002
The earliest known human remains discovered up to 1994 in the European region were found at Broxbourne in southern England although earlier evidence of humans has since been found in Spain. Broxbourne man was of similar height and weight to modern men of the region. Only a bone and a tooth were found so it seems that almost all human remains decay in northern latitudes over 500,000 years or so which is the time elapsed. Human remains last much longer in the dry conditions of eastern and southern Africa and because scientists have to try and avoid too much speculation and concentrate on physical evidence not much time is given to the idea that human development occurred more in the northern lands - but it is possible. Probably the human form developed in Africa but more sophisticated culture developed in the northern environment where conditions were harsher. Genetic research at Oxford University has now shown that people of the Scandinavian region have origins traceable back about 40,000 years while other waves of immigration moved into northern Europe later. When the early migrants from Africa via the Mediterranean and Middle East arrived in the northern lands they must have been forced to build better shelters and to make better clothing to prepare for the winter's cold. They were probably forced to cooperate more in order to survive. The winter was a natural time for the production of artifacts. So it seems that the long winters led them to begin the manufacturing and trading system we know today which ultimately enabled the northern peoples to play a leading role in the world's affairs.
Mitochondrial DNA is almost entirely inherited from mothers and seems to show that all modern humans descended from a single female who was in Africa about 120,000 years ago although a gene, beta globin, has a longer lineage in China and Australia than in Africa. Researchers at Oxford have also found longer lineages for beta globin in the Oxford area. Cranial features of modern humans in Asia seem to be derived partly from the members of homo erectus who lived in that area while modern Europeans are more like homo erectus types of Europe. Since homo erectus only died out in Java about 25,000 years ago it makes it seem likely that there was some inter-breeding which is difficult to reconcile with the mitochondrial evidence to date. Also, researchers in Israel have found types which seem intermediate between modern humans and Neanderthalers although it is now believed that the differences in DNA are too great for Neanderthalers to be our ancestors and they are no more closely related to Europeans than they are to modern Chinese.
The ice age which lasted from 186,000 to 120,000 years ago must have caused people to move southwards at its onset and it seems reasonable to suppose that they were relatively able people who had adapted to the difficulties involved in surviving in the colder lands. Then, in Africa, intermarrying may have occurred giving an even more viable culture largely because of the particularly strong variant of mitochondrial DNA which is involved in the power supply in cells. Greater energy and strength of the new type of humans would have allowed them to take over from homo erectus although where those earlier types managed to intermarry with females of the new type the mitochondrial DNA they could therefore pass on to their descendants would have enabled them to prevent their other characteristics from disappearing completely.
McGraw-Hill's Encyclopedia of Science and Technology indicates that mitochondrial changes play a role in cytoplasmic male sterility and if there had been such an effect it would have made for a quicker takeover by the newer type of humans when some of their daughters had intermarried with peoples they encountered in their migrations. The advantage which the new mitochondria conferred need not have been very great for a gradual takeover to have occurred in such a long period and the seeming desirability of intermarriage with the newer peoples may have been at the root of legends which linger on about kidnap of human children by monsters such as the trolls, who are portrayed as being like humans but slower and not so intelligent. The legends may owe something to Neanderthalers or homo erectus.
Greater size was an advantage to people in the north but the thicker skulls and heavy brow ridges of the Neanderthalers may owe something to a culture which relied more on the use of clubs in fighting while the superior technology of modern humans led to greater use of spears when mobility became more of an advantage than size. It is interesting that Australian Aborigines retained a ritual clubbing ceremony in relatively recent times since it tested the strength of the skull and it seems increasingly certain that they have been in Australia since well before the Neanderthalers and homo erectus became extinct.
During the slow drift back toward the north after the end of the last ice age, as the climate improved, two main choices were presented by the geography of Eurasia. There were the wide-open spaces of Eastern Europe or the plains and coasts of the North Sea and Baltic Sea areas. It seems that the strongest peoples managed to take over in the northern areas giving rise to the Maglemosian culture from which it is now known northern Europeans are mostly descended. That helps to account for the far-reaching effects of peoples who spread out from the northern lands more recently.
Copyright©2002Andrew Burbidge
