Scientists Fight To Prove Humanity 'Born In Africa'

Born In Africa: The Quest For The Origins Of Human Life
By Martin Meredith
Hardcover, 288 pages
PublicAffairs
List Price: $26.99

May 12, 2011

Setting out on foot across the Maasai Steppe in 1913 at the head of a column of fifty porters, Hans Reck, a twentyseven-year-old German geologist, had no clear idea how to find his destination. Behind him rose the snow-capped peak of Kilimanjaro, the highest mountain in Africa. Ahead lay volcanic highlands lining the Great Rift Valley. Reck's mission was to investigate a ravine to the west of an extinct volcano named Ngorongoro that had aroused keen interest in Berlin. But he had been given only vague instructions about its location.

Two years before, a German entomologist, Professor Wilhelm Kattwinkel, had stumbled across the ravine by chance while leading a medical expedition to this remote part of what was then German East Africa (now Tanzania). When Kattwinkel had asked local Maasai tribesmen the name of the ravine, they had thought he was referring to the wild sisal growing there ? Sansevieria ehrenbergii ? and had told him they called it 'oldupai'. Kattwinkel had duly recorded the name of the ravine in German as 'Oldoway'.

Exploring the eroded slopes of Oldoway, he had made a small collection of ancient fossils, taking them back with him to Berlin. When it was realised that some of the bones belonged to an unknown species of three-toed horse, there was considerable excitement. With the personal support of the kaiser, a new expedition had been authorized under the auspices of the Universities of Berlin and Munich, and Hans Reck had been chosen to lead it.

A specialist in volcanology, Reck had already proved his ability to handle African expeditions. In 1912, he had been appointed leader of a university expedition to Tendaguru in the southern region of German East Africa which had uncovered a complete skeleton of a Braciosaurus, one of the largest land animals ever to have lived. His team of porters from Tendaguru had joined him for this new expedition. But the journey across the Maasai Steppe proved arduous: In the searing heat Reck's column struggled to keep pace and was strung out for miles. Water was scarce.

Climbing up the western escarpment of the Great Rift Valley onto the slopes leading to Ngorongoro, Reck caught sight in the distance of Ol doinyo Lengai, the Maasai's 'Mountain of God', so named because it was still an active volcano. Reaching the rim of Ngorongoro, he marvelled at the spectacle around him: Below lay a collapsed crater, twelve miles across and 2,000 feet deep, forming a natural amphitheatre of 100 square miles that teemed with wildlife. Once rising to a height of 15,000 feet, the Ngorongoro volcano had exploded 2.5 million years ago, causing its dome to crumple inwards and leaving walls that were only half their original size.

But Reck was still unable to find out anything about Oldoway. A German official he met at Ngorongoro had never heard of it. Local Maasai also had no information, but they agreed to show him the way to a spring called Langavata on the western side of Ngorongoro which overlooked the great Serengeti Plains stretching away to the horizon.

For three days, Reck wandered along the fringes of the Serengeti. Then on 7 October 1913, he set up camp on the rim of a steep gorge. The surrounding terrain seemed familiar. Looking at photographs that Professor Kattwinkel had taken two years previously, Reck realized that he had found Oldoway.

In the months that followed, Reck collected more than 1,700 fossils and completed a geological survey of the area. He discovered that the gorge offered a remarkable geological record of past millennia. Its walls consisted of five distinct layers, or 'beds', of lava and ash, providing a sequence of time dating far back into antiquity. At the base was a layer of black lava; above stood a layer cake of colours ? rich copper sandwiched between duller buffs and greys. No means of accurate dating were then available. But in time Oldoway was to yield crucial clues about the importance of the volcanic regions of the Great Rift Valley in revealing the origins of humankind.

The Great Rift Valley acts as a history book of the deep past. Over the last 10 million years, as two of Africa's tectonic plates have slowly pulled apart, a giant fissure has developed in the earth's crust, running for more than 3,000 miles from the lower reaches of the Zambezi Valley in Mozambique, through eastern Africa to the Red Sea where it divides Africa from Arabia. Tectonic upheavals and volcanic eruptions have transformed a relatively flat rain-forest region into a dramatic landscape of mountains, lakes and a complex array of fractures, faults and scarps. Ethiopia's landmass rose 8,000 feet above the surrounding plains, like a huge blister on the continent's skin, to form the largest volcanic massif in Africa. Eruptions in Kenya built a similar dome. Most of the uplift occurred after 7 million years ago. To the west, running parallel to the main Rift Valley, a new fissure began to develop, creating another chain of mountains and lakes, including Lake Tanganyika, the deepest lake in Africa, where the lake bottom lies 2,200 feet below sea level. Shoulders of land along the western rift were pushed up to form new mountain ranges such as the Rwenzori massif, the fabled Mountains of the Moon once thought by ancient Greek geographers to be the source of the Nile. Many of the ancient lake basins along the Rift have since disappeared, buried under layers of lava, ash, sand and mud, sediments which have subsequently been thrust upwards by tectonic movements and then exposed by erosion from wind and rain. Among the sediments lie millions of fossils, giving glimpses of life long past.

Oldoway was once part of the shoreline of a shallow alkaline lake formed about 2 million years ago and fed by streams and rivers spilling down from the volcanic highlands to the east and south. Volcanic ash from two active volcanoes ? Olmoti and Kerimasi ? was periodically deposited on the lake, blown there by the prevailing wind. Over a period of about 400,000 years, the lake gradually shrank and disappeared. In more recent times ? about half a million years ago ? a seasonal river began to cut its way through the accumulated layers of lake sediments and ash deposits, eventually carving out a steep-sided gorge, with cliffs that in places fell 300 feet. By chance, part of the gorge followed the shoreline of the prehistoric lake, an area rich in ancient fossils, as Hans Reck discovered.

In December 1913, after nearly three months exploring Oldoway, Reck was almost ready to leave when one of his workmen reported finding a human skeleton buried in a crouched position in what was called Bed II, one of the oldest layers in the gorge wall. When he inspected the site, Reck immediately understood its significance. The skeleton clearly belonged to a modern human ? Homo sapiens ? but it lay at a level where extinct Pleistocene animals had been found. If the skeleton was as old as its surroundings, then it meant that it wasone of the oldest human finds ever made.

Excerpted from Born In Africa by Martin Meredith. Reprinted by arrangement with PublicAffairs, a member of the Perseus Books Group. Copyright 2011.

Source: http://www.npr.org/2011/05/12/136247011/scientists-fight-to-prove-humans-born-in-africa?ft=1&f=5

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