Human Evolution


Evolution is the complexity of processes by which living organisms established on earth and have been expanded and modified through theorized changes in form and function. Human evolution is the biological and cultural development of the species Homo sapiens sapiens, or human beings. Humans evolved from apes because of their similarities. This can be shown in the evidence that humans had a decrease in the size of the face and teeth that evolved. Early humans are classified in ten different types of families. Creationists believe that humans were always humans.

Humans are classified in the mammalian family Primates. In this arrangement, 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. Two-leg walking seems to be one of the earliest of the major hominine characteristics to have evolved. In the course of human evolution the size of the brain has been more than tripled. The increase in brain size may be related to changes in hominine behavior (See figure 3). The third major trend in hominine development is the gradual decrease in the size of the face and teeth.

According to the Microsoft Encarta Encyclopedia \'98, the fossil evidence for direct ancestors of modern humans is divided into the category Australopithecus and Homo, and begins about 5 million years ago (See figure 1). Between 7 and 20 million years ago, primitive apelike animals were widely distributed on the African and, later, on the Eurasian continents (See figure 2). Although many fossil bones and teeth have been found, the way of life of these creatures, and their evolutionary relationships to the living apes and humans, remain matters of active discussion among scientists.

The evidence for human evolution begins with the australopithecines. All the australopithecines were bipedal and therefore possible hominines. In details of their teeth, jaws, and brain size, however, they modify enough among themselves to be divided into five species: Australopithecus anamensis, A. afarensis, A. africanus, A. robustus, and A. boisei. Genus Homo are also divided in five different spices: Homo erectus, H. habilis, H. sapiens, and H. sapiens sapiens. According to Britannica Encyclopædia, Australopithecus anamensis lived in Kenya between 4.2 million and 3.9 million years ago. A. afarensis lived in eastern Africa between 3 and 4 million years ago. This australopithecine had a brain size a little larger than chimpanzees. Some had canine teeth more sticking out than those of later hominines. No tools of any kind have been found with A. afarensis fossils.

According to Microsoft Encarta Encyclopedia \'98, between about 2.5 million and 3 million years ago, A. afarensis clearly evolved into A. africanus. A. africanus had a brain similar to that of its ancestor. However, although the size of the chewing teeth remained large, the canines, instead of sticking out, grew only to the level of the other teeth. No stone tools have been found in association with A. africanus fossils. The more recent include the A. robustus, limited to southern Africa, and A. boisei, found only in eastern Africa. The robust australopithecines represent a specialized adaptation because their principal difference from other australopithecines lies in the large size of their chewing teeth, jaws, and jaw muscles.

According to Microsoft Encarta Encyclopedia \'98, Homo erectus lived from about 1.8 million to 30,000 years ago. Until recently, Homo erectus was considered an evolutionary ancestor of modern humans, or Homo sapiens. Homo erectus had a larger brain than earlier hominines. Homo erectus was also a taller, with an evenly face and smaller tooth. Scientists believe this species lived in Africa between 2 million and 1.5 million years ago. H. habilis is the earliest known member of the genus Homo. H. habilis had a larger brain than australopithecines. Australopithecines had long arms and short legs, similar to the limbs of apes. Even, H. habilis were similar modern humans with its limbs and small body size relative to its height. H. habilis had smaller molars teeth and a less raised face than earlier Hominines. H. habilis was taller than australopithecines, but shorter than Homo erectus. H. sapiens are not identical in aspect with modern humans. H. sapiens sapiens, first appeared more than 90,000 years ago.

The opposition doesn\'t think the same way as scientists do. Creationists say that human ancestors