Human evolution is the theory which states that humans developed from primates, or ape-like, ancestors. In 1856, a strange skull was found by some workmen in the Neander Valley in Germany. The odd appearance of the skull led some to believe that it had once belonged to a person who was afflicted with rickets. They did not believe it could have come from an ancestor of modern man. It did, however, form the notion that there could have been creatures that were half-human and half-ape. Ernst Heinrich, a German scientist, claimed that if such a creature were ever found it should be named Pithecanthropus erectus, which means upright apeman.

Even before the discovery of the skull, which is now known as Homo neanderthalensis, people hypothesized that there was some sort of transmutation took place between species. This, however, was not widely accepted. On November 4, 1859, the view on evolution as a whole changed dramatically. This was the date that Charles Darwin published his work The Origin of Species. With the release of this work, the theory of human evolution became a bit more believable. The theory of natural selection was proposed by Darwin within The Origin of Species. This theory states that the physical traits of an organism are selected for according to the environment it lives in.

Darwin's theory peaked the interest of many scientists who went out in search of skulls which would branch the gap between apes and humans. In 1890, a Dutch physician by the name of Eugene Dubois found a low, apelike skull on the banks of a river in Java. Dubois also discovered a humanlike thigh bone near the skull. He concluded that this creature was the link between apes and humans which Heinrich hypothesized about. Other fossils began to be found which appeared to be transitional.

In 1925, Raymond Dart found a skull which was the first to be classified as Australopithecus. The skull looked apelike in appearance, but had humanlike teeth. Dart discovered the skull in a box of fossilized bones sent to him from Tuang. Mary and Louis Leakey also found a number of Australopithecine fossils. The Leakey's main area of focus was the Olduvai Gorge in Tanzania. Another researcher, Donald Johanson, found similar fossils in the Afar region of Ethiopia. Johanson is credited with finding the fossil skeleton of "Lucy", an Australopithecus afarensis, which shows that ancestors of humans were walking upright at around 3.6 million years ago.

As the amount of finds increased, so did the number of species. Today, the Australopithecus genus includes:

• A. anemensis
• A. afarensis
• A. africanus
• A. boisei
• A. robustus
• A. aethiopicus

(A. is an abbreviation for Australopithecus)

Even though these fossils had both human and ape characteristics, the apelike qualities outnumbered the human ones. Scientists sought to find fossils that were closer to modern man than the Australopithecines. In the early 1960's, Louis Leakey found what he thought was another A. boisei skull, however, the brain case was larger than previous finds. After collaboration with P.V. Tobias and J.R. Napier, he named the skull Homo habilis, which means "handy man". He came up with this name because of the tools found at the site of the skull. Leakey figured that the enlarged brain size made it possible for H. habilis to form tools according to how his/her mind perceived it should look like. Other species of this genus that were found include H. erectus, H. sapiens neanderthalensis, and our own species, H. sapiens sapiens.

Some controversy concerning the labeling of H. sapiens neanderthalensis has arisen in past years, as to whether it should be considered part of the sapiens line. Previously, Neanderthals were considered to have been the transitory form from H. erectus to H. sapiens sapiens. The ideology then shifted to a position that Neanderthals were not a transitory form, but were instead a genetic dead end. Their abrupt disappearance in the fossil record has yielded suggestions that Neanderthals were outcompeted and replaced by anatomically modern human beings. The current viewpoint among many people is that Neanderthals were in fact a separate species and have been labeled by some as H. neanderthalensis, dropping "sapiens" from the name.

Information provided by: http://www.anthro.mankato.msus.edu