Human Evolution

This chapter traces the origin and evolution of modern man, Homo sapiens sapiens, through the fossil record, the evolutionary time scale, and the succession of ancient and modern human ancestors.

Origin and evolution of man

To find out the origin and evolution of modern man (Homo sapiens sapiens), many anthropologists have carried out vast studies. The fragmentary fossil records available so far suggest that men arose in the plains of Asia, Africa and Europe from some non-human or ape-like forms which lived 20-24 million years ago.

Evolutionary trend

An evolutionary trend is the general pattern of change of organisms from their ancestral states. The human evolutionary changes are as follows:

• Loss of opposability of the great toes.
• Erect posture through development of the lumbar curve.
• Increase in the size and complexity of the brain.
• Development of the chin.

Evolutionary time scale

The fossil records suggest that men and modern apes had a common ancestor known as hominids. It is presumed that hominids existed 24 million years ago.

1. Gibbon diverged from the main lines about 10 million years ago.
2. Orangutan diverged from the main lines about 8 million years ago.
3. Human evolved about 2.3 million years ago.

Ancient human fossils

The fossils of Ramapithecus, Sivapithecus and Australopithecus are considered the ancient human fossils. These fossils are assumed to have originated from a common ancestor for the origin of both apes and man, i.e. Dryopithecus or Proconsul.

1) Ramapithecus

• Considered the direct ancestor of man.
• Includes a curved jaw with an arched plate.
• May have lived in Nepal about 11 million years ago.

2) Australopithecus

• The first human-like form, which existed about 1 to 2.5 million years ago in the dry land of South Africa.
• Brain capacity was 600 cc.
• They walked upright and showed more similarity to man.
• They probably weighed about 40-50 kg.
• They were about 4-5 ft tall.