Evolution of Homo Erectus
In the thirty-four million years between the time of the Old World anthropoid Aegygptopithecus, and the appearance of Homo Erectus, our primate predecessors went through a world of change. The fossil, climatic, and archaeological evidence available to us allows us to examine how individual characteristics, both physical and cultural, allowed these creatures to respond and adapt to a changing environment. These characteristics did not develop simultaneously, but as part of a process of mosaic evolution - separate traits and behaviors developed at different times for different reasons. To understand how our ancestors came to be, we must examine how and why these separate characteristics evolved over time.
Though we cannot be sure exactly when the split between Old World monkeys and hominids occurred, we have evidence that it happened sometime after 35-33 million years ago (m.y.a.) (Turnbaugh 190). Dating back to this time are fossils of Aegygptopithecus.
This genus of primate was a fruit-eating, arboreal quadruped that was about the size of a modern howler monkey. It had a hominoid dental pattern, but also a very small brain and long snout, linking it to both Old World Monkeys and hominids. Since Aegyptopithecus appears to be an ancestor to both groups yet shares the derived traits of neither group, we may conclude that it was at the root of their split.
The Miocene, which took place 23-5 million years ago, is known as the Age of the Apes. In the early Miocene, the movement of South America and Australia changed ocean currents as the pressing of the South Asian plate into Asia created the Himalayan Plateau. As a result, the climate began to warm in comparison to the preceding Oligocene epoch (Turnbaugh 191). This hot and wet environment was ideal for the apes of the time, and...