| |
Olduvai Gorge is a canyon carved by water through
the southern part of the Serengeti Plain. The gorge is about 50
km long and in some places 90 metres deep. It drains the slopes
of the nearby mountains plus the Serengeti Plain. Its chief claim
to fame is the rich treasure-trove of human and animal fossils that
it has yielded.
History of archaeological work at Olduvai
In 1911, a German entomologist, Professor Kattwinkel, was the first
European to enter the gorge. He noticed many fossil bones, identified
as an extinct three-toed horse. This inspired Professor Hans Reck
to lead an expedition to Olduvai in 1913. he found a hominid skeleton,
but further work was halted by World War I. some years later, Louis
Leakey saw the Olduvai fossils in Berlin and was convicted that
Olduvai must hold valuable clues to human origins. In 1931, Leakey
organised an expedition to the Gorge with Reck, and found stone
tools within a few hours of arriving at the gorge.
In further excarvations, Leakey and his wife Mary found and described
many stone tools and fossil animals, but found no significant hominid
("human-like") fossils until 1959, when Mary Leakey discovered
the first skull of "Zinjanthropus". Now renamed Australopithecus
boisei, this creature had a massive skull with huge teeth that
suggested a diet of coarse vegetable food, and lived 1.75 million
years ago.
1976 Mary Leakey discovered a fossil hominid and animal tracks at
Laetoli, a site twice as ancient as anything at Olduvai.
It is well worth visiting the site where "Zinj" was found,
just five minutes' drive from the visitor centre. Ask the guides
for the latest discoveries!
A reconstruction of hominid history
3,500,000 years ago, our very remote ancient ancestors walked through
a landscape very like that which we see today. The volcanoes were
fewer but more active then, though Ngorongoro had not yet towered
high above the others. On one particular day, the volcano Sadiman
puffed out a lot of grey ashes, so that the local animals left crisp,
clear tracks when they walked. Some of the creatures have changed
little; hares were abundant, guinea-fowl scurried about, giraffes
strode regally over the plain. Others are no longer with us, such
as an elephant with downward-curving tusks in its lower jaw, and
Hipparion, a three-toed horse.
Through this desolate grey landscape that would
later be named Laetoli travelled through hominids. Shorter than
ourselves (1.2 to 1.4 metres high), they may have looked more than
apes than people, but they walked on two legs. A large, a medium-sized
and a small individual walked together, the medium-sized one stepping
in the tracks of its large companion. A day or two later, a fresh
ash-fall buried the tracks, until they were excavated in 1978. We
know from contemporary fossils that the footprints were made by
Australopithecus afarensis, an early hominid.
It is tempting to wonder why these ape-like, small
brained creatures (450cc; our own brains average 1400cc) walked
upright - could they see further afield? Did they use their hands
for carrying water, food, or babies? Or did they carry sticks, stones
or thorn branches to fight off neighbouring hominids, or predators?
If they carried such weapons, did they use them in self-defence
or to stela kills from hunters?
1,890,000 years ago, the volcano Olmoti erupted,
and thick lava flows covered the area now occupied by Olduvai Gorge.
burying any earlier remains beneath black basalt. A lake soon formed
there, and became the focus of activity for a wide variety of animals.
Its alkaline waters provided ideal conditions for fossilizing dead
animals and plants falling in it.
The descendants of Laetoli's upright-walkers were at Olduvai. Two
different kinds of hominids left remains in the deepest level of
the gorge, Australopithecus boisei and homo
habilis ("handy man").
1,500,000 years ago, earth movements and faulting
caused "Lake Olduvai" to be drained. At this time australopithecus
afarensis was still presented, while homo habilis had evolved to
homo erectus ("upright man"), our direct
ancestors. This human had a bigger brain (900cc) and made better
stone hand-axes. Only 17,000 years ago homo sapiens
lived in the gorge.
|
|
