Marc Verha
Thu, Jul-10-03, 19:14
Out of Africa
How long ago did our ancestors begin to migrate from Africa?
Evidence from a massive volcanic explosion 74,000 years ago in
South-east Asia is giving researchers clues about these first
colonists, says Stephen Oppenheimer 09 July 2003 Much has been
made of the evidence from the so-called Adam and Eve genes,
which support the notion that all modern humans alive today
have descended from ancestors living in Africa within the past
200,000 years. A recent find of skeletons in Ethiopia, dated
to 160,000 years ago, confirms the final transitions between
pre-modern and anatomically modern humans in Africa. But the
fine details and dates of early human explorers do not just
come from advances in the study of genes and bones. Traces of
a great natural disaster may allow us to pinpoint just when
humans first left Africa. The scene of the disaster is Lake
Toba which today is a popular tourist spot in Sumatra. Toba is
the largest lake in South-east Asia - 100km long and 31km wide
- and, at 450m deep, it is one of the deepest in the world.
Tourists may be unaware that Toba is also the world's largest
active volcanic crater. About 74,000 years ago the volcanic
eruption of Toba caused the biggest explosion of the past two
million years. This "mega-bang", dwarfing the historic
eruption of Krakatoa, caused a six-year "nuclear winter" and
released ash in a huge plume that spread to the north-west,
covering the Indian sub-continent in a blanket of ash between
one and three metres deep. The Toba eruption is a valuable
date mark, since the ash covered such a wide area, and can
still be chemically identified today. New genetic evidence,
using genes only passed down through our mothers, suggests
that the ancestors of all non-Africans left Africa, as a
single group, via Aden as much as 80,000 years ago. If the
date is correct, their descendants could have reached
South-east Asia well before the Toba explosion, most likely by
beachcombing along the coast of the Indian Ocean. Stone tools
have been found covered by volcanic ash from Toba in Kota
Tampan in the Malay Peninsula. Were these the tools of modern
humans, therefore backing up the genetic evidence for modern
humans reaching Sumatra before the Toba explosion? Or were
they the tools of an earlier human species? Recent re-dating
of the volcanic ash layer at Kota Tampan, which is several
metres thick, has forced an extraordinary reappraisal of the
significance of the site. The Kota Tampan site with its
evidence of a Palaeolithic human culture is located in the
Lenggong Valley, two-thirds of the way from Africa to
Australia. This culture was first identified by the find of
large pebble-tools, fashioned on one side only. In the absence
of skeletal remains at Kota Tampan, the tools were initially
thought by archaeologists in the 1960s to be the work of an
earlier human species. On the face of it, these were not
sophisticated tools. Full text http://news.independent.co.uk/-
world/science_medical/story.jsp?story=423003
How long ago did our ancestors begin to migrate from Africa?
Evidence from a massive volcanic explosion 74,000 years ago in
South-east Asia is giving researchers clues about these first
colonists, says Stephen Oppenheimer 09 July 2003 Much has been
made of the evidence from the so-called Adam and Eve genes,
which support the notion that all modern humans alive today
have descended from ancestors living in Africa within the past
200,000 years. A recent find of skeletons in Ethiopia, dated
to 160,000 years ago, confirms the final transitions between
pre-modern and anatomically modern humans in Africa. But the
fine details and dates of early human explorers do not just
come from advances in the study of genes and bones. Traces of
a great natural disaster may allow us to pinpoint just when
humans first left Africa. The scene of the disaster is Lake
Toba which today is a popular tourist spot in Sumatra. Toba is
the largest lake in South-east Asia - 100km long and 31km wide
- and, at 450m deep, it is one of the deepest in the world.
Tourists may be unaware that Toba is also the world's largest
active volcanic crater. About 74,000 years ago the volcanic
eruption of Toba caused the biggest explosion of the past two
million years. This "mega-bang", dwarfing the historic
eruption of Krakatoa, caused a six-year "nuclear winter" and
released ash in a huge plume that spread to the north-west,
covering the Indian sub-continent in a blanket of ash between
one and three metres deep. The Toba eruption is a valuable
date mark, since the ash covered such a wide area, and can
still be chemically identified today. New genetic evidence,
using genes only passed down through our mothers, suggests
that the ancestors of all non-Africans left Africa, as a
single group, via Aden as much as 80,000 years ago. If the
date is correct, their descendants could have reached
South-east Asia well before the Toba explosion, most likely by
beachcombing along the coast of the Indian Ocean. Stone tools
have been found covered by volcanic ash from Toba in Kota
Tampan in the Malay Peninsula. Were these the tools of modern
humans, therefore backing up the genetic evidence for modern
humans reaching Sumatra before the Toba explosion? Or were
they the tools of an earlier human species? Recent re-dating
of the volcanic ash layer at Kota Tampan, which is several
metres thick, has forced an extraordinary reappraisal of the
significance of the site. The Kota Tampan site with its
evidence of a Palaeolithic human culture is located in the
Lenggong Valley, two-thirds of the way from Africa to
Australia. This culture was first identified by the find of
large pebble-tools, fashioned on one side only. In the absence
of skeletal remains at Kota Tampan, the tools were initially
thought by archaeologists in the 1960s to be the work of an
earlier human species. On the face of it, these were not
sophisticated tools. Full text http://news.independent.co.uk/-
world/science_medical/story.jsp?story=423003