The evolutionary path from the original primates to modern man is a long one and has taken many twists and turns, but naturally, as the fossil record grows, scientists gain a more complete understanding of our own mental and physical history in terms of genetics and anatomy. However, the correct order and relationships of the various specimen types are difficult to pin down. Many representative samples have been found in such minute amounts as to not preclude anomalies. They have been discovered in various stages of wear. Modern features did not occur simultaneously or uniformly, taking millions of years to become manifest in later types. Up to the present day’s Homo sapiens, examples of the main types have been hybrids of older and more modern features.
One of the earliest species of the genus Homo to be discovered is Homo habilis, which basically means “handy man.” The name comes from the belief at the time of its discovery that this species was the first to start using stone tools. The first fossils to be uncovered in Olduvai Gorge were from the same stratigraphic layer as simple stone tools. Fossils of the crania and postcranial skeleton for this species have been found in both eastern and southern Africa and date to around 2.5–1.6 million years ago.
Features of Homo erectus suggest an evolution toward modern humans, and the features which separate Homo erectus from the other Homo species are found in the skull. The size of the brain was approximately 900 cc, making it larger than the brain size of Homo habilis. Homo erectus would not have the largest brain capacity of the Homo genus during its existence, with the emergence of Homo heidelbergensis approximately 800,000 years ago. The larger brain size may not matter much when the size of the brain is considered with the size of the body, which also increased.
