Here's how we got here, there and everywhere

Brockie's view of peopling the world.
BOB BROCKIE

Brockie's view of peopling the world.

Homo sapiens evolved in Africa about 200,000 years ago.

We remained there until some enterprising souls dispersed out of Africa to settle in the Levant or Middle East about 100,000 years ago. Over the last month or two scientists have revealed what happened next.

Most people left Africa in four waves. A few pioneer Africans dispersed to Europe more than 100,000 years ago but never established there. They probably died out.

About 50,000 years ago, one batch wandered as far as Java and Australia. Some even sailed to Okinawa. Then, 45,000 years ago, another wave overran Europe.

A fourth batch dispersed to Siberia and North America between 15,000 and 20,000 years ago. As these new waves of migrants spread they did not supplant the earlier settlers but interbred with them.

Hawaiian scientists Axel Timmermann and Tobias Friedrich have surveyed and mapped all sorts of events that overtook Asia, Europe and the Far and Middle East during the past 125,000 years.

In astonishing detail, they have analysed local climates and monsoon seasons, volcanic eruptions, carbon-dioxide levels, contracting and expanding ice- and sea-levels during four Ice Ages, and coastal areas and plant-cover spreading or contracting over this long period.

Today the Arabian Desert would block any human and animal dispersal out of Africa. But between the Ice Ages, the monsoons and wetter climate promoted plenty of plant cover along the Arabian and Sinai Peninsula coasts.

These corridors provided resource-rich migration routes and drew early populations out of Africa coinciding with inter-glacial periods.

When sea levels dropped by 100m, coastal areas widened and continents changed shape. These changes enabled early people to migrate along the broader coasts of India and Malaysia to the Far East, to walk from Malaysia almost to Australia, from France to Britain, from Siberia to Alaska and from mainland Australia to Tasmania.

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The India-Malaysia coastal route is purely speculative for, although we have tonnes of human fossils from Africa and the Far East, we have only one old human fossil between the two.

Traces are rare probably because rising sea-levels inundated the coasts, along with their human skeletons and artefacts. The Hawaiians admit there are still gaps in their knowledge but they are working on them.

During the past fortnight, 32 international scientists, including two from Waikato and Massey universities, have cleared up a mystery about the earliest Polynesian settlers in the Pacific.

For some time we have known that Polynesian people originated in Taiwan about 3000 years ago. It was widely thought that as these people dispersed through Indonesia and New Guinea towards the Pacific, they picked up some Papuan genes.

Now the international team has examined the DNA of 778 present-day East Asians and Pacific Islanders, plus the DNA of a 3000-year-old skeleton from Vanuatu and 2500-year-old bones from Tonga.

The team concludes that Pacific Islanders came not through Indonesia and Papua New Guinea but directly from Asia. They think New Guinea blood mixed with Pacific Islanders' blood later on.

 - Stuff

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