Africans or Asians?

The Negrito tribals of the Andamans have been objects of scientific curiosity since the colonial times. Two of these groups -- the Jarawas and the Sentinelese -- have largely escaped the anthropologist's gaze. But the other two, the Onge and the Sentinelese, have been subjected to intensive scrutiny. The origin of these islanders, in particular, has been a source of much anthropological debate.

In 1875, the British anthropologist Geoge E Dobson was the first to note the physical similarities between Andaman's Negritos and the pygmoid people of Africa. In an article in the Journal of the Royal Anthropological Institute, Dobson suggested that their small stature, peppercorn hair and small-boned skeletal structure, made the Andamanese Negritos distinctly similar to the pygmoids of Southern Africa.

But some recent studies dispute this connection. For example, a study by Kumarasamy Thangaraj and his colleagues from the Centre for Cellular and Molecular Biology, Hyderabad, and the Estonian Biocenter in Riia, Estonia -- published in Current Biology , Vol 13, No 2, 2003 indicates that the Andamanese have close affinity with communities in Southeast Asia.

But wait The African connections theories have not gone out of vogue. These analyses take their cue from a volcanic eruption in Sumatra, Indonesia, about 73,000 years back: called the Toba ytt, the eruption measured 8 on the Volcanic Explosivity Index -- used to determine the intensity of volcanic eruptions. It's the only eruption of this intensity since primates appeared on Earth. 1010 million tonnes of sulphuric acid and lava gushed out of the Toba at around 750 c, blanketing huge parts of Southeast Asia . Few living creatures -- and certainly no human -- survived such fury.

But the volcano theory still doesn't explain the African origin of the Andamanese. The ancestors of the Negritos could well have arrived from Southeast Asia before the Toba erupted. A study by S K Acharyya and his colleagues from the Geological Survey of India, New Delhi -- published in Quaternary Research, Vol 40, No 1, 1993 -- tries to set such doubts to rest. Acharyya and his associates note that the summer monsoons carried ash from Toba ytt to the Indian subcontinent. The entire subcontinent was blanketed with ash -- in places as thick as 6 metres. All plant and animal life on the Indian subcontinent -- including the Andamans -- was wiped out. So, Acharrya and associates surmise that the Negritos settled in the Andamans much after Toba ytt.

The great migration... But we still have no substantive evidence of the African connection. The proponents of the theory turn to the Toba ytt again. They cite studies which have proved that dust clouds in the aftermath of the eruption obscured the sun and lowered temperatures of the North Sea by 1 c. A tmospheric temperatures fell by 3 c-5 c in the Northern Hemisphere and the ice-age followed Toba ytt.

Swiss geologist George Weber notes that in the aftermath of the ice-age there was a mass exodus of Homo sapiens from the cooler locales of Africa to Asia. Some even migrated to the Andamans.

This theory still does not offer an exact date for the migration. It's very likely that the gaze of the modern scholarship will continue to probe the Andamanese.