This is a dissertation chapter on Evolution:
Primate Evolution
Fossils representing the precursors of the primates may go back before the extinction of the dinosaurs, 65 million years ago. There are some primate-like teeth and bones found in Montana and Wyoming, dated from 60 to 65 maya. But the first undisputed primates appear about 55 maya. These early primates, despite the modern primate arboreal theme, may not themselves have been arboreal. As these primates continue to evolve, these basic traits prove a useful adaptive response to a more generalized life in the trees. Later the eastern and western hemispheres became completely separate, dividing the early primates into two geographical groups. The early new world primates were apparently replaced by more advanced monkey like primates that migrated from Africa to the Americas when the two continents were closer together by “island hopping” over a chain of volcanic islands or by rafting. Apes appear in the fossil record about 23 maya. With the evolution of larger bodies and larger brains, they became a successful group of primates.
The Evolution of Bipedalism
Bipedalism was the first hominid feature to evolve millions of years before our big brains and flat faces. Each new fossil or new date or new interpretation of ancient environments changes the outlook slightly. Early hominid fossils found in eastern and southern Africa have long been linked to the Savannas that began expanding because of climate changes about 5 maya. It freed the forelimbs to carry things, including offspring and food. The vertical orientation helped cool the body by exposing a smaller surface area to the intense equatorial rays of the sun, and by placing more of the body above the ground to catch cooling air currents. It was very efficient and required less energy for long periods of steady walking. (more…)
