Our Ancestors: Hominids
An extinct group of primates that lived from about 12 to 14 million years ago, for a time regarded as a possible ancestor of Australopithecus and, therefore, of modern humans. Fossils of Ramapithecus were discovered in N India and in E Africa, beginning in 1932. Although it was generally an apelike creature, Ramapithecus was considered a possible human ancestor on the basis of the reconstructed jaw and dental characteristics of fragmentary fossils. A complete jaw discovered in 1976 was clearly nonhominid, however, and Ramapithecus is now regarded a member of Sivapithecus, a genus considered to be an ancestor of the orangutan."
Ramapithecus was very apelike in appearance.
About 4 million years ago, parts of what is now eastern Africa were inhabited by small hominids who walked upright all the time. Those are our earliest direct ancestors. We have no fossil remains of them, but we know that they developed into two subgroups. One of these groups is called Australopithecus. The earliest fossil hominid is of a female Australopithecus, whose bones are 3.2 million years old. She was discovered in Ethiopia in 1974 by American scientist Donald Johanson, named Lucy.
An ape woman called Lucy. Lucy is the nickname of the fossil female Australopithecus. By studying the knee and hip joints, scientists are certain she was a female who walked upright like a modern human. She was about 1.2 m ( 4 ft.) tall and died at about age 23.
By about 2.5 million years ago, two distinct kinds of Australopithecus had emerged. One was larger and stronger, and is called robust type. The other was more slender. It is called the gracile type. Both probably carried sticks and threw stones. But no tools have been found with their remains. All types of Australopithecus became extinct about 1 million years ago.
Nothing is known about the other side of the hominid family tree until around 2.5 million years ago, when the first true humans appeared. The earliest type is know as Homo habilis ("skillful man"). The earliest fossil remains of Homo habilis coincide with the first real tools-crudely shaped pieces of stone. Big stones were used for smashing animal bones to get at the marrow, and sharp flakes of rock were used to cut up the meat.
About 1.5 million years ago the next type emerged, Home erectus ("erect man"). These humans were able to make better tools, by chipping stones into cutting tools called hand axes. Groups of Homo erectus in different areas of Africa developed different techniques of making stone tools. By about 1 million years ago, Homo erectus used fire, had invented cooking, and had begun to spread out from Africa.
Lucy belonged to the earliest known species of Australopithecus called afarensis. Her brain was only about quarter the size of a modern human's brain. Although her descendants grew taller and stronger, their brains remained about the same size and they never learned to make tools.
The brain of Homo habilis was about half the size of a modern human's brain, but was twice as large as that of Australopithecus. This increase in brain power enabled Homo habilis to learn how to make the first crude stone tools, which could be used to cut up meals.
Homo erectus had a brain about two-thirds modern size. The increase in brain size over Homo habilis was quite small. However, it was enough to enable Homo erectus to develop quite sophisticated stone tools, and to learn how to make and use fire. After fire was mastered, Homo erectus moved north to cooler climates, using fire to keep warm.