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The Evolution of mankind - Important Points
The Savannah Theory
Some Anthropologists argue that Hominids began to walk only on their hind legs as they need their hands for hunting on the African Savannah and an upright stance to see enemies form afar. And from there the name of the theory. But some scientists such a Elaine Morgan appose this theory saying that animals need more speed on the Savannah , both for pursuit and flight, than two legs can offer.
The Term Hominids
Hominids is a super family including four genera: chimpanzee, gorillas, humans and orangutans. All genera having the same body structure.
For two million years, the early hominid was a tribal animal, primarily a herd herbivore. During the next two million years the human was a tribal hunter and still is. All of the humans social drives developed long before he developed intellectually. They are, therefore, instinctive. Such instincts were all necessary for the survival of the human and pre-human.
Examples of a hominoid are the great apes. They are large, tailless primates. In all species are the males larger and stronger than the females and all are able to use their hands for gathering food or in some cases for tool use. Most species are omnivorous, but fruit is the preferred food among all but humans.
Humans, since the neolithic revolution, consume mostly cereals and other starchy food, including highly processed foods.
Bipedal posture and locomotion undoubtedly represented the first and most decisive evolutionary change of hominids but it is by no means such a radical innovation as is commonly assumed.
Mans erect posture was prepared for by the shortening and widening of the trunk and the associated shift of the spinal column towards the center of the trunk, a basic trend to all higher primates. When the earliest hominids had left the forest, the need for a higher level of vision led to the upright posture and even the erect walk more and more frequently and thereby the hands became free for purposes other than locomotion.
The Aquatic ape Theory
Elaine Morgan argues that bipedalism emerged from life in an aquatic due to the flooding of the African rift valley millennia ago. Apes that suddenly found themselves stranded in swamp land had to walk upright to keep from drowning.
The first period in man's evolution
Orrorin tugenensis – Considered the second oldest known Hominid ancestor that is possibly related to modern humans. Orrorin is significant because it can be an early bipedal hominid. The age of the specimen has been estimated to 6 million years ago. At presents only 20 fossils have been found.
Australopithecus afarenis – is an extinct hominid that lived about 3.5 million years ago. A. afarenis was slenderly built, like the younger A. africanus, although it is thought to be more closely related to the genus Homo.
The most famous fossil is the partial skeleton named Lucy. Strangely A.afarensis had a smaller brain capacity than some earlier species.
There is considerable debate regarding the locomotion of this species. Some believe that A.afarensis was almost exclusively bipedal, while others believe that the creatures were partly arboreal. The anatomy of the hands,feet and shoulder joints in many ways favour the latter interpretation.
Australopithecus africanus – A..a was a early hominid, which lived between 2-3 million years ago in the Pliocene era. It is assumed to be a direct ancenstor of modern humans. Fossil remains indicate that A.africanus was significantly more like modern humans than A.afarensis with a more human-like cranium permitting a larger brain and more humanoid features. Main traits of the A.a are bipedalism, slightly larger arms than legs ( a trait also found in chimpanzees and ape-like curved fingers for climbing are also present.
Australopithecus garhi – is believed to be the final missing link between the Australopithecus genus and the human genus, Homo. It has the same cranial capacity as earlier australopithecus species. Garhi was also the first Hominids to have stone tools. A.G. Is for sure a bipedal humaniod.
Paranthropus robustus – Originally discovered in Southern Africa in 1928. Dated to have lived around 2 million years ago. Its development namely aimed in the direction of a heavy-chewing complex – robust characteristics such as large jaws, jaw muscles and post-canine teeth that were adapted to serve in the dry environment that they lived in. In a cave at Swartkrans in South Africa the remains of 130 individuals were discovered. This discovery revealed that P. robustus rarely lived past the age of 17.
Paranthropus boisei – largest of the Paranthropus species. Lived during the Pliocene and Pleistocene epochs in Eastern Africa. First discovered on 17th July 1959 in Tanzania. Its brain Capacity was slightly bigger than the Australopithecus species and had a specialized skull for heavy chewing and several traits seen in modern day gorillas.