Human origin is based on dated fossil remains of the various hominid existence. Each species may have existed earlier or later, but fossil proof has not yet been discovered. There is also dispute concerning many overlapping species. The overlap between Homo habilis and Homo erectus. It could well be that the two are continuing examples of the same species. The same dispute exists with Homo erectus, archaic Homo sapiens and Homo sapiens sapiens.
Most anthropologists agree that Australopithecines belong to the same family as modern day humans, Hominidae. From there they are classified into the genus Australopithecus, which means "southern ape", and into four species, afarensis, africanus, boisei and robustus. There is little agreement, however, on the role that these individuals played in the evolution of the Homo line. Some believe that Australopithecus afarensis was the common ancestor of both the Homo line and the rest of the Australopithecus line. Others believe that this split occurred later on with Australopithecus africanus.Still others argue that these two lines developed side by side by a different common ancestor.In all three cases, both lines were evolved from a common ancestor somewhere in the past that served to separate them from the apes.
Australopithecus afarensis and africanus are the gracile forms of this species with rather small and light body structures. Australopithecus robustus and boisei, were more robust individuals with a rather heavy bone structure with big teeth and saggital crest
Australopithecus afarensis fossils were discovered by Taieb and Johanson in Hadar, Ethiopia named Lucy.
Australopithecine afarensis was adapted to bipedalism, appear apelike above the neck and humanlike below the neck and dated 2.9 to 3.5 million years ago. The oldest A. afarensis was dated 5.6 years ago from northern Kenya. Louis and Mary Leakey founded substantial evidence at Olduvai Gorge. In 1959 the Leakeys found a 1.75 million year old, well preserved Australopithecine skull. Also Mary Leakey discovered the famous Laetoli footprints of 3 hominid dated 3.6 million years ago and was bipedal. A. afarensis still retained the ability to climb tress. Brain size was between 300-400cc for graciles and 400-500cc for robust. They were primarily vegetarian.
Homo habilis was called the handy man because tools were found with his fossil remains. This species existed between 2.4 and 1.5 million years ago. The brain size in earlier fossil specimens was about 500cc to 800cc. Richard Leakey in Kenya uncovered many hominid fossils. One find was the most complete Homo habilis skull.
The species brain shape shows evidence that some speech had developed. Habilis was about 5' tall and weighed about 100 pounds. In Omo Valley, Ethiopia, Homo habilis remains were found to be contemporary with Australopithecus finds. Some scientists believe that habilis is not a separate species and should be carried either as a later Australopithecine or an early Homo erectus. They were bipedal and dentition evidences shows meat in their diet.
Homo erectus lived between 1.8 million and 300,000 years ago. It was a successful species for a million and a half years. Brain size was between 900cc to 1200cc. The species definitely had speech. Erectus developed tools, weapons and fire and learned to cook his food. He traveled out of Africa into China and Southeast Asia and developed clothing for northern climates. He turned to hunting for his food. Only his head and face differed from modern man. Like habilis, the face had massive jaws with huge molars, no chin, thick brow ridges, and a long low skull. Though proportioned the same, he was sturdier in build and much stronger than the modern human.
Richard Leakey also found several Homo erectus remains at East Turkana in 1976. This fossil was removed from a layer of sediment that also contained Australopithecine remains indicating that these two species lived during the same time period and in the same region.
In 1894, a Homo erectus called Java Man was dug from the banks of an Indonesian river, his discoverer Eugene Dubois triumphantly declared him the missing link between apes and humans.
Choukoutien cave in Dragon Bone Hill, China, has provided us with numerous Homo erectus remains as well as many interesting artifacts. The tools have been manufactured from quartz using a flake process. Examination of the site has revealed that the people who used this site were part of a hunter-gatherer society
In Lantian, China, the oldest known of any Homo erectus sites dating back 800,000 years.
Homo sapiens (archaic) provides the bridge between erectus and Homo sapiens sapiens during the period 200,000 to 500,000 years ago. Many skulls have been found with features intermediate between the two. Brain averaged about 1200cc and speech was indicated. Skulls are more rounded and with smaller features. Molars and brow ridges are smaller.
Homo sapiens neanderthalensis lived in Europe and the Mideast between 150,000 and 35,000 years ago. Neanderthals coexisted with H.sapiens (archaic) and early H.sapiens sapiens. It is not known whether he was of the same species and disappeared into the H.sapiens sapiens gene pool or he may have been crowded out of existence by the H.sapien sapien. Brain sizes averaged larger than modern man at about 1450cc but the head was shaped differently, being longer and lower than modern man. He was a massive man at about 5'6" tall with an extremely heavy skeleton that showed attachments for massive muscles. He was far stronger than modern man. His jaw was massive and he had a receding forehead, like erectus.
Homo sapiens sapiens first appeared about 120,000 years ago. Modern humans have an average brain size of about 1350