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PinkMonkey Online Study Guide-Biology

12.2 Ancestral forms of Homo sapiens

As mentioned earlier, the palentological (fossil) record for human evolution is not continuous. Ever since the theory of evolution become scientifically acceptable, biologists and anthropologists have been trying to find the ‘missing link’, the species that would bridge the gap between humans and the great apes which are the closest living relatives of humans. The fossils collected from various regions indicate possible trends in human evolution. Some important ancestral forms of Homo sapiens are described below.

(1) Dryopithecus

It appears from fossil evidence, that humans and apes (Hominids) have both descended from a common ancestor, called Dryopithecus, that lived 20 million years ago (Miocene epoch). The first Dryopithecus fossils were found in 1930 on an island in Africa’s lake Victoria by Dr. Lewis Leakey. Later on they were also found in Africa, N. India, China and Europe. The Dryopithecus were first described as Sivapithecus, Proconsul and Ramapithecus. Dryopithecus were contemporary to another genus, Pliopithecus. These appear of be ancestors to apes and humans. Important anthropoid characters of Dryopithecus included a somewhat flattened face, a shortened jaw, enlarged incisors (typical of apes, but not human), arms and the legs of the same length and must have assumed a semi-erect posture on the ground and were more bipedal than the other apes.

Figure 12.3 Human Evolution

(2) Australopethicus

Australopithecus africans represents the next known step in human evolution. The fossil remains from Africa belonged to early Pleistocene era (1.2 - 3 million years ago) and named by Raymond Dart in 1924. It weighed 40-60 pounds, bipedal form of primates, walked in an entirely erect posture, a distinct lumbar curve and had human-like teeth. The dental arch was a smoothly rounded parabola. However, Australopithecines had jaws and teeth larger than those of modern man. It had an ape-brain (capacity 450-700 cc.) rather than a human brain.

They were living in groups assumed to be using tools (made by chipping pebbles) since the fossils are often found with piles of bones of hares, birds, baboons. This indicates that they were true hunter scavengers, who actually hunted animals they ate. Another form of hominid, Australopithecus robustus, appeared later, weighed 150-200 pounds, walked erect and had a brain size similar to that of the ape.

Another type of hominid creature lived in the place and period as Australopithecus and was also bipedal, but had a larger brain and used tools. It was placed in genus Homo - its full name is Homo habilis (habilis = mentally skillful).

Table of Contents

12.0 Introduction
12.1 Palaeontological Evidences - Our Ancestors
12.2 Ancestral Forms of Homo Sapiens

Chapter 13


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