The origins of man could now be placed in the heart of Africa. The Great Rift Valley is an ancient geological feature and it has many secrets. This incredible fracture of the earth is volcanic and stretches from Ethiopia down through Kenya into Tanzania and beyond, into Mozambique
Finding a hominid fossil is important. Uncovering even a partial skeleton is a big deal in scientific circles. Hominid fossils are extremely rare. In fact finding a fossil of any kind of creature is remarkable, simply because conditions have to be perfect for fossils to be made at all.
Olduvai Gorge was discovered in 1911, but it was Mary and Louis Leakey's archaeological excavations from 1935 onwards that escalated the studies of early man with a number of discoveries. It became clear to many that Africa was where humans originally evolved from.
Thousands of stone tools were found over many years, but Mary's unearthing of a robust hominid (a more primitive species than early man) in 1959, caused quite a stir on the ladder of evolutionary thinking at the time. The Leakey's next discovery in 1960 of what is now known as "Homo habilis" seemed to indicate 2 different species of hominid living in the same time frame. It seems that one was a tool maker and went on to survive, while the other became extinct.
The Leakeys unearthed 2 skull bones and the lower jaw of a child. They were the first fossils ever found of "Homo habilis", also known as the Handy Man. This type of early human had a bigger brain, finer jaw and smaller teeth than its predecessors.
Homo habilis appears to have made an evolutionary leap with the use of primitive stone tools to process food by cutting, crushing and scraping. As a result, it is thought that the refined facial features developed over time because heavy jaws and bigger teeth were no longer required for powerful chewing, grinding and tearing.
When the Leakeys made their discoveries at Olduvai Gorge, a new benchmark was set. All kinds of questions about human evolution suddenly required answers: What did the hominids eat? Was there co-operative behaviour in a type of camp? How were the stone tools made and where were the rocks sourced from?
Fossils can be created in a number of ways - it's a complex process but many clues about the creature and the environment in which it lived are revealed. Water and its many forms can be one of the components in fossilisation. Did this Homo habilis live near water? When you look now at the dusty Serengeti Plains it seems unlikely, but this early type of human lived around 2 million years ago, so was there a lake there at that time?
Olduvai Gorge continues to be a source of incredible reference. There have been many discoveries to date with at least 60 hominid fossils showing the development of human lineage including those found by the Leakeys. The site shows occupation from 2 million years ago until about 15 000 years before present.
Olduvai Gorge is located in the eastern Serengeti ecosystem in the Ngorongoro Conservation Area which is a UNESCO World Heritage Site. The Serengeti Plains of Northern Tanzania are renowned for the biggest annual Wildebeest migration in the world.
Olduvai Gorge is about 48km (30 miles) long. There is a museum on the edge of the ravine where visitors can learn more about fossil excavation and see exhibits of finds from the gorge and its surroundings. One hall is dedicated to the Leakey family while a second hall depicts information for another of Mary Leakey's discoveries, the Laetoli fossilised footprints trail - this archaeological site is located 45km (28 miles) south of Olduvai Gorge.