Human Evolution a Timeline

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"Human Evolution a Timeline"
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Wiser men than I, psychologists, philosophers and theologians have debated human evolution for centuries. What remains clear from this era of enlightenment, is that the truth about humanity and our origin may be found only through factual knowledge and factual knowledge lies in a process called evolution. Humanity is what evolution made it.

Man has had tribal instincts since he first walked tall, more than four million years ago. With the impediment of being bipedal, he could not out-climb or outrun his predators. Only through co-operation with other tribal groups was he able to hold his predators at bay.

For two million years, the early hominid was tribal, but over the next two million years he evolved to a hunter/warrior. This remains the status quo ante to this day and so it follows that humanity's social drive developed long before he developed in any intellectual sense. It could therefore be said that we are, instinctive and that such instincts are ancient and remain embedded in our make-up and was therefore necessary for the survival of humanity. Since human social drive is instinctive (not intellectual), it cannot be modified through learning.

Human intellect, the magnitude of which separates us from all other animals, developed slowly over four million years, or perhaps more, of human evolution. Intellect is not unique to us, but is quite well developed in a number of other higher animals. It evolved as a control over instinct to provide adaptable behaviour so as to provide optimum survivability. This process is called self-control or self-discipline, and is the major difference between human and lower animals, those that apply only instinct to their behavioural decisions. Self-discipline, therefore, is the measuring stick for humanity. The more disciplined behaviour displayed by the individual, the more human he or she becomes. The reverse can be said for animals of a lower order.

The direct lineage from the ancestor of both man and the modern apes to modern man is not known however evidence is increasingly coming into the open. The word hominid is used to describe the total member species in the human family that have existed since the last common ancestor of both man and the apes. A hominid is an individual species within that family. The field of science which studies the human fossil record is known as palaeoanthropology and is closely linked to the disciplines of palaeontology (the study of ancient life forms) and anthropology (the study of humans). Each hominid name consists of a genus name for example Australopithecus, Homo, and a species name for example africanus, erectus.

The time line for the existence of the various hominid are based on dated fossil remains. Each species may have existed earlier, but fossil proof has not been discovered in this regard. I offer therefore the following chronology:

Dated at 4.4 million years old the earliest fossil hominid, Ardipithecus ramidus, is a recent discovery and the remains are incomplete but, enough evidence is available to suggest it was bipedal. Fossils were found which would suggest that ramidus was a forest dweller and herbivore.

Named in 1995 a new species, Australopithecus anamensis, was found in Allia Bay in Kenya. It is believed that Anamensis lived between 4.2 and 3.9 million years ago; its body showing advanced bipedal features, but still with the skull closely resembling ancient apes.

Australopithecus afarensis turns up next; living between 3.9 and 3.0 million years ago. Still retaining an apelike face with a sloping forehead, a distinct ridge over the eyes, flat nose and a chinless lower jaw, it had a brain capacity of about 450 cc. Fully bipedal, the thickness of its bones showed that it was quite strong with a build which was about the same as a modern human. A larger head with powerful jaws is a feature of all species prior to Homo sapiens.

Australopithecus africanus: quite similar to afarensis, lived between three and two million years ago. Also also bipedal, it was slightly larger in body size with a brain size which was also slightly larger, ranging up to 500 cc. The brain was however still not advanced enough for speech to develop as a primary form of communication. The shape of the jaw was now like the human.

Next we find, Australopithecus aethiopicus which lived between 2.6 and 2.3 million years ago. A species which was probably an ancestor of the robustus and boisei this hominid had huge molars and jaws and a large sagittal crest. Its brain size was similar to that of africanus, about 500cc, and again with no indication of speech function.

As stated above, Australopithecus robustus was probably a descendant of aethiopicus and lived between two and 1.5 million years ago. With a body similar to that of africanus, its huge face was flat and with no forehead. Its brain size ha developed and was now up to 525cc however there was still no indication of speech capability.

Similar to robustus, but with an even more pronounced face, Australopithecus boisei lived between 2.1 and 1.1 million years ago. It had huge molars and a brain size which was about the same as robustus.

was called the handy man because tools were found with his fossil remains. The species Homo habilis comes next on our list and existed between 2.4 and 1.5 million years ago. With a brain size rising to 800cc toward the end of the species life period it shows evidence that some speech had developed. Some scientists believe that habilis is not a separate species and should be carried either as a later Australopithecine or an early Homo erectus. It is possible that early examples are in one species group and later examples in the other.

Between 1.8 million and 300,000 years ago Homo erectus arives and survived for nearly 1.5 million years. Early examples had a 900cc brain size on average but grew steadily during its reign. Toward the end its brain was almost the same size as modern man, at about 1200cc and it can be said with confidence that it definitely had speech function. Erectus, also know colloquially as he handy man, developed tools, weapons and created fire learning to cook food. He travelled out of Africa into China and Southeast Asia and developed clothing for northern climates. He turned to hunting for sustainance.

Homo sapiens is regarded as the bridge between erectus and Homo sapiens during the period 200,000 to 500,000 years ago. Many skulls have been found with features intermediate between the two. Both with a brain a about 1200cc and speech function indicated the skulls are more rounded, with smaller features.

Finally we come to Homo sapiens neandertalensis which lived in Europe and the Mideast between 150,000 and 35,000 years ago and Cro-Magnon which lived from about 40,000 to 10,000 years ago in the Upper Palaolithic period of the Pleisocene epoch. Neanderthals coexisted with Cro-Magnon but it is widely believed that the latter caused the extinction of the former. Surviving Cro-Magnon artifacts include huts, carvings and antler-tipped spears. Remains of tools discovered suggest that Cro-Magnon knew how to make woven clothing and may have created the first known calender around 15,000 years ago.

Whilst abbreviated this chronology shows the depth of similarity found along the line and importantly that with an increase in brain size, and the development of speech function came more human skills and abilities.

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