paleoanthropology1: A human origin example of how science evolve (v1.0)

 Key references are prof John Hawks of university of Wisconsin, Madison and Wikipedia.

Science evolves over time. Understandings at one point in time may be overturned or modified at a later point in time as new data comes in. This is part and parcel of the scientific method. A well-known Physics example is the transition from Newtonian physics to Relativity.

The science of anthropology and more particularly the subspecialty of paleoanthropology focuses on the evolution of humans. It often takes decades to resolve questions and sometimes you have to wait until a right new fossil specimen has been found. A variety of techniques are used in its investigations including anatomy, fossil studies, skeletal studies, genetic studies, microscopic studies, and chemical studies. The key questions are how we are related to other kinds of fossil hominins, and how we are connected to other kinds of primates. They painstakingly construct species family trees.  The story of Ramapithecus (ape man) which was the root of the human family tree (the root ancestor of us all) at one time, clearly illustrates how science evolves.

The Ramapithecus fossil (Rama is the Hindu deity and pithecus is ape) was first found by a British scientist in the Siwalik hills of modern day Pakistan in 1932 and is around 14 million years old. No significance was attached to those fossils until 1960, when American anthropologist Elwyn Simons of Yale University began studying them and fit the jaw fragments together. On the basis of his observations of the shape of the jaw and of the morphology of the teeth—which he thought were transitional between those of apes and humans—Simons advanced the theory that Ramapithecus represented the first step in the evolutionary divergence of humans from the common hominoid stock that produced modern apes and humans. Simons’s theory was strongly supported by his student English-born American anthropologist David Pilbeam and soon gained wide acceptance among anthropologists. 

The first challenge to the theory came in the late 1960s from American biochemist Allan Wilson and American anthropologist Vincent Sarich, who, at the University of California, Berkley, had been comparing the molecular chemistry of albumins (blood proteins) among various animal species. They concluded that the ape-human divergence must have occurred much later than Ramapithecus (It is now thought that the final split took place some 6 million to 8 million years ago.)

Wilson and Sarich’s argument was initially dismissed by anthropologists, but biochemical and fossil evidence mounted in favor of it. Finally, in 1976, Pilbeam discovered a complete Ramapithecus jaw, not far from the initial fossil find, that had a distinctive V shape and thus differed markedly from the parabolic shape of the jaws of members of the human lineage. He soon repudiated his belief in Ramapithecus as a human ancestor, and the theory was largely abandoned by the early 1980s.

Ramapithecus fossils subsequently were found to resemble those of the fossil primate genus Sivapithecus, which is now regarded as ancestral to the orangutans.