Evolution of Man

Evolution of Man

The first arboreal, shrew-like insectivorous animals gave rise to Primates, an order of class mammalia. In this order man belongs. Fossil history shows that primates evolved during Paleocene. From early prosimians or first primates five groups of animals radiated. These were –

(i) Lemuroids – Lemurs (long snout) of Madagascar island.

(ii) Tarsoids –Tarsier (short neck) of southern Asia and lndonesia.

(iii) Ceboids- New world monkeys with prehensile tail of South and Central America.

(iv) Carcopithecoids-Old world monkeys with non-prehensile tail Africa and Asia.

(v) Hominoids –Represented by apes and man. During early Miocene period hominoid gave rise to two branches –one formed pongids or apes (i.e. gibbons, orangutans, chimpanzees and gorillas) and the other gave rise to hominids to which man belongs.

There are some similarities between apes and man. There are (i) absence of tail; (ii) legs are long; (iii) broad sternum leading to broad and flat breast; (iv) 4 or 5 lumbar vertebrae; (v) brain and cranial cavity large; (vi) omnivorous nutrition and development of domestic life. But these two also differ in some characters. These are (i) apes are arboreal while man is terrestrial; (ii) apes are with thick hairs all over the body while man has lesser hairs on limited regions of the body;(iii) apes have upper lip without median furrow but this is present in man;(iv) well developed mammary glands in females but not so in apes;(v) separate pre-maxilla and maxilla in apes but in man these are fused;(vi) ‘U’ shaped dental line in ape but semicircular in man;(vii) incisors and canines a little larger than other teeth in ape but in man these are almost of the same length like other teeth;(viii) in ape foramen magnum at the posterior end of skull which lies in front of vertebral column but in man the skull lies anterior to vertebral column; (ix) power of speech and imagination lacking in apes but present in man;(x) brain and cranial cavity is comparatively smaller in apes than in man.

1. Pre-Apes

During the study of fossil history of man scientists came across many fossils of pre-apes. The important among them are –

1. Propliopithecus and Pliopithecus – These are fossils of Oligocene period which resemble more with ape and man than monkey. These are considered to be the stage from where the evolutionary-series of ape and man started.

2. Limnopithecus and Pliopithecus –These are fossils of miocenc and Pliocene period. These are considered as members of a branch which separated from evolutionary line of apes an

man and became extinct afterwards.

3. Procunsul –During Miocene period ape and monkey were undergoing evolutionary changes in Africa and India. During this time a famous fossils was discovered which is named as Procunsul Africana. Incomplete skeleton of Procunsul was discovered in Victoria lake, Africa during 1948 by Dr. Leake. In some characters it stands between ape and man. The skull was round like man but long canine was like ape.

Scientists believe that Procunsul was at such a evolutionary step from where preman and ancestors of pre-ape (primates) diverged but was not in the direct line of the evolution of man. This skeleton was 2crore50lac of years old.

4. Dryopithecus –The fossil of this pre-ape was obtained from middle Miocene and early Pliocene strata of Europe and Africa.

5. Shivapithecus –It was another pre-ape whose fossil was discovered from Miocene strata of Siwalik hill of India. Its skull and hands were like monkey but jaw with teeth was ape-like. From this stage ancestors of man and ape separated.

On the basis of the accumulated evidences it is very difficult to say when man evolved. Human evolutionary changes are the following –

(i) Erect posture (ii) shortening of arms (iii) reduction in size of teeth (iv) loss of jaw power (v) increase in skull capacity (vi)reduction of brow ridges (vii)power of articulated speech (viii)utilization of tools and weapons. The present fossils indicate that man has originated from ancestor man-like ape in Africa. Skeleton and experiments associated with serum show that man had closer relation with man-like gorilla, chimpanzee etc. So we can accept that man and man-like ape descended from some common ancestor.

2. Pre historic Man

During evolution of man, there appeared several races which existed for sometimes and then became extinct. These are called pre-historic man.

(A) Pre-hominid Ancestors(man ape)

(a) Ramapithecus and Kenyapithecus- Fossils of these prehominid were found in Siwalik hills of N-W India by G.E.Lewis(1930) and during Miocene and Pliocene strata of Africa and China by L.S.B.Leakey (1955). These were prehomonid ancestors because these had-

(i) semicu