Evolution of Man Section
Introduction to Evolution of Man
There is no longer any doubt among the scientists about the fact of evolution as the central theme of nature. Organic evolution is a general principle of biology, applying equally to all living forms. There is overwhelming evidence generated by the biologists, anthropologists, geologists and paleontologists to demonstrate that man has evolved in the same way as did the other animals. We have inherited physical traits from related animals because of our common ancestry at one point of time or the other throughout our evolutionary history.
This has been possible because genes or the DNA (Deoxyribonucleic acid), the hereditary material is relatively immortal as it is passed down through generations with or without changes, through mutations, in a breeding population. These accumulated gene mutations in a species give rise to sub species or new species and serve as the basis of organic evolution.
Charles Darwin (1809-1882) had demonstrated this fact long ago without any knowledge of genetics or without any primate fossil evidences at his disposal. He based his observations on the isolated animal groups and primitive societies of mankind around the world. He had understood the role of natural selection and the role of geography and environment as modifying factors in the process of organic evolution. When Darwin published his books "On the Origin of Species by Means of Natural Selection" (1859) and the "Descent of Man" (1871), it had a stimulating effect on biologists and a setback to the protagonists of the theory of special creation of man in his present form. In the last century or so, significant fossil evidences have been dug up from Africa, Europe and Asia to substantiate Darwin's postulates and place the sequence of human evolution in its correct perspective.
It is now certain that early generalized mammals like the mouse and squirrel as early as 100 to 90 million years ago were responsible for providing primitive primates with hands and feet having four fingers and four toes with opposable thumbs and opposable greater toes for grasping purposes which were helpful to them in their arboreal life. The concomitant changes that followed in the body with respect to the placement of internal body-organs accordingly, were most suited for erect posture, while sitting and manipulating food. Other associated features such as binocular vision and more evolved brain were also developing in the now extinct primates know as Adapis dating back to 60 million years. These were the earliest common ancestors of the present day prosimians, the extinct prosimians, and Old-World and New-World Monkeys and fossil apes around 50 million years ago. Human and Ape-ancestry broke off from Old-World Monkeys about 40 million years ago which gave birth to present day apes and man separately about 5 to 7 million years ago.
Some of the important stages through which primate evolution proceeded have been traced back to now extinct apes such as Pliopithecus, who gave rise to present day gibbons.Similarly, the extinct Proconsul or Dryopithecus of Africa and Europe and South-east Asia and the Sivapithecus of India were giving rise to Chimpanzee, Gorilla and Orangutan respectively.
Recently discovered Sahelanthropus, the precursor of the Australopithecus genera gave rise to several lineages of ape-like man who produced Hominids, such as Homo habelis or Homo erectus and Peking-Man and Homo heidelbergensis who gave birth to Cromagnon Man and Grimaldi Man and other Homo sapiens of Africa, Asia and Neanderthal-Man of Europe respectively. These early-men gave rise to present day human populations in Africa, Asia and Europe.
The evolutionary history of man as reconstructed on the basis of fossil evidences has been corrobrated by the recently developed molecular (DNA) technology by establishing the evolutionary relationship among different genera of apes; man-like apes; ape-like man; and fossil Homo sapiens and the living human populations.
DNA studies have also suugested that Neanderthal-Men did not contribute to the modern population of Europe or perhaps the Neanderthal-Men had died out before the arrival of Homo sapiens in Europe.
While the earlier part of human evolution can be summed up as the evolution of erect posture and bipedalism, the later part is seen as the evolution of his brain with amazing powers of abstraction and anticipation, ability to develop elaborate tool technology on stone, bone and antler and expressing their artistic talent as cave painters.
J.C. Sharma, M.Sc., Ph.D., Retd. Prof. Of Anthropology, Panjab University, Chandigarh.