The Rational Optimist_ How Prosperity Evolves - Matt Ridley [31]
This great movement from Africa to Australia was not a migration, but an expansion. As bands of people feasted on the coconuts, clams, turtles, fish and birds on one part of the coast and grew fat and numerous, so they would send out pioneers (or exile troublemakers?) to the east in search of new camp sites. Sometimes these emigrants would have to leapfrog others already in possession of the coast by trekking inland or taking to canoes.
Along the way they left tribes of hunter-gatherer descendants, a few of whom survive to this day genetically unmixed with other races. On the Malay Peninsula, forest hunter-gatherers called the Orang Asli (‘original people’) look ‘negrito’ in appearance and prove to have mitochondrial genes that branched off from the African tree about 60,000 years ago. In New Guinea and Australia, too, the genetics tell an unambiguous story of almost complete isolation since the first migration. Most remarkable of all, the native people of the Andaman islands, black-skinned, curly-haired and speaking a language unrelated to any other, have Y-chromosome and mitochondrial genes that diverged from the common ancestor with the rest of humankind 65,000 years ago. At least this is true of the Jarawa tribe on Great Andaman. The North Sentinelese, on the nearby island of North Sentinel, have not volunteered to give blood – at least not their own. As the only hunter-gatherers who still resist ‘contact’, these fine-looking people – strong, slim, fit and stark naked except for a small plant-fibre belt round the waist – usually greet visitors with showers of arrows. Good luck to them.
To reach the Andaman islands (then closer to the Burmese coast, but still out of sight) and Sahul, however, the migrants of 65,000 years ago must have been proficient canoeists. It was in the early 1990s that the African-born zoologist Jonathan Kingdon first suggested that the black skin of many Africans, Australians, Melanesians and ‘negrito’ Asians hinted at a maritime past. For a hunter-gatherer on the African savannah, a very black skin is not needed, as the relatively pale Khoisan and pygmies prove. But out on an exposed reef or beach, or in a fishing canoe, maximum sunscreen is called for. Kingdon believed that the ‘Banda strandlopers’, as he called them, had returned to conquer Africa from Asia, rather than the other way round, but he was ahead of the genetic evidence in coining the idea of an essentially maritime Palaeolithic race.
This remarkable expansion of the human race along the shore of Asia, now known as the ‘beachcomber express’, has left few archaeological traces, but that is because the then coastline is now 200 feet under water. It was a cool, dry time with vast ice sheets in high latitudes and big glaciers on mountain ranges. The interior of many of the continents was inhospitably dry, windy and cold. But the low-lying coasts were dotted with oases of freshwater springs. The low sea level not only exposed more springs, but increased the relative pressure on underground aquifers to discharge near the coast. All along the coast of Asia, the beachcombers would have found fresh water bubbling up and flowing into streams that meandered down to the ocean. The coast is also rich in food if you have the ingenuity to find it, even on desert shores. It made sense to stick to the beach.
The evidence of DNA attests that some of these beachcombers, on reaching India and apparently not before, must have eventually moved inland, because by 40,000 years ago ‘modern’ people were pressing west into Europe and east into what is now China. Abandoning the crowded coast, they resumed their old African ways of hunting game and gathering fruits and roots, becoming gradually more dependent on hunting once more as they inched north into the steppes grazed