Human evolution

Human evolution is the process of change and development, or evolution, by which human beings emerged as distinct species. It is the subject of a broad scientific inquiry that seeks to understand and describe how change and development took place. The study of human evolution encompasses many scientific disciplines, but most notably physical anthropology and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominids, such as the australopithecines.

History of paleoanthropology

The modern field of paleoanthropology is said to have begun with the discoveries of Neanderthal “man” and evidence of other "cave men" in the 19th century. The idea that humans were similar to certain great apes was obvious to people for some time, but the idea of biological evolution of species in general was not legitimized until after Charles Darwin published Origin of Species in 1859. Though Darwin's first book on evolution did not touch on the question of human evolution—"light will be thrown on the origin of man and his history," was all Darwin wrote on the subject—it was clear to contemporary readers what was at stake. Debates between Thomas Huxley and Richard Owen focused on the idea of human evolution, and by the time Darwin published his own book on the subject (Descent of Man), it was already a well-known interpretation of his theory—and the aspect of it which made it highly controversial. Even many of Darwin's original supporters (such as Alfred Russel Wallace and Charles Lyell) balked at the idea that human beings could have evolved their apparently boundless mental capacities and moral sensibilities through natural selection.

Related Topics:
Paleoanthropology - Neanderthal - 19th century - Charles Darwin - Origin of Species - 1859 - Thomas Huxley - Richard Owen - Descent of Man - Alfred Russel Wallace - Charles Lyell - Natural selection

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Since the time of Carolus Linnaeus the great apes were ranked as being the closest animals to human beings, based on morphological similarity. In the 19th century it was speculated that our closest living relatives were chimpanzees and gorillas, and based on the natural range of these creatures, it was surmised that human ancestor fossils would ultimately be found in Africa and that humans share a common ancestor with African apes.

Related Topics:
Carolus Linnaeus - Great ape - Common ancestor

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It was not until the 1920s that fossils other than neanderthalensis were discovered. In 1925, Raymond Dart described Australopithecus africanus. The type specimen was the Taung Child, an Australopithecine infant discovered in Taung, South Africa. The remains were a remarkably well-preserved tiny skull and an endocranial cast of the individual's brain. Although the brain was small (410 cc), its shape was rounded, unlike that of chimpanzees and gorillas, more like a modern human brain. Also, the specimen exhibited short canine teeth and the position of the foramen magnum was evidence of bipedal locomotion. All these traits convinced Dart that the Taung baby was a bipedal human ancestor, a transitional form between "apes" and humans. Another 20 years would go by before Dart's claims were taken seriously, following the discovery of more fossils that resembled Dart's find. The prevailing view of the time was that a large brain evolved before bipedal locomotion. It was thought that intelligence on par with modern humans was a prerequisite to bipedalism.

Related Topics:
Raymond Dart - Australopithecus africanus - Type specimen - Taung Child - Taung - South Africa - Foramen magnum

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The Australopithecines are now thought to be the immediate ancestors of the genus Homo, the group to which modern humans belong. Both Australopithecines and Homo are part of the family Hominidae, but recent data has brought into doubt A. africanus position as a direct ancestor of modern humans; it may well have been a dead-end cousin. The Australopithecines were originally classified as either gracile or robust. The robust variety of Australopithecus has since been reclassified as Paranthropus. (In the 1930's when the robust specimens were first described, the Paranthropus genus was used. During the 1960s the robust variety was moved into Australopithecus. The recent trend has been back to the original classification as a separate genus.).

Related Topics:
Hominidae - Paranthropus

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