Evolution

10 Pages 2492 Words

Human Evolution, the biological and cultural development of the species Homo
sapiens, or human beings. A large number of fossil bones and teeth have been
found at various places throughout Africa, Europe, and Asia. Tools of stone,
bone, and wood, as well as fire hearths, campsites, and burials, also have been
discovered and excavated. As a result of these discoveries, a picture of human
evolution during the past 4 to 5 million years has emerged.

Human Physical Traits Humans are classified in the mammalian order Primates;
within this order, humans, along with our extinct close ancestors, and our
nearest living relatives, the African apes, are sometimes placed together in the
family Hominidae because of genetic similarities, although classification
systems more commonly still place great apes in a separate family, Pongidae. If
the single grouping, Hominidae, is used, the separate human line in the hominid
family is distinguished by being placed in a subfamily, Homininae, whose members
are then called hominines—the practice that is followed in this article. An
examination of the fossil record of the hominines reveals several biological and
behavioral trends characteristic of the hominine subfamily.

Bipedalism Two-legged walking, or bipedalism, seems to be one of the earliest of
the major hominine characteristics to have evolved. This form of locomotion led
to a number of skeletal modifications in the lower spinal column, pelvis, and
legs. Because these changes can be documented in fossil bone, bipedalism usually
is seen as the defining trait of the subfamily Homininae.

Brain Size and Body Size Much of the human ability to make and use tools and
other objects stems from the large size and complexity of the human brain. Most
modern humans have a braincase volume of between 1300 and 1500 cc (between 79.3
and 91.5 cu in). In the course of human evolution the size of the brain has more
than tripled. The increase...