Scientists have many different theories about the origins, or beginnings, of modern humans. In general they believe that human beings developed over time from early apelike ancestors. This process of development is called evolution. Scientists do not all agree about exactly how the ancestors evolved into modern humans. In fact, they are forming new theories about this all the time. Most scientists do agree, however, that modern humans belong to a scientific family known as hominids and that they developed in stages.
Background
Scientists believe that apes and humans are related because they developed from a common ancestor millions of years ago. This does not mean that humans evolved from modern chimpanzees or other apes. Both humans and individual apes evolved independently after they separated from the common ancestor. Although human beings share almost 99 percent of their genetic material with chimpanzees, the differences between them are great. For example, humans use spoken language, walk on two legs, and have much larger brains than chimpanzees. Because of these and other differences, chimpanzees and humans are considered separate species.
Scientists have only a small amount of evidence to use in determining human origins. This evidence is generally found in the form of fossils, or remains of earlier creatures that have been preserved in the earth. The study of fossils is called paleontology. In Africa, Asia, and Europe, scientists have found skeletal remains and tools from very early time periods. Each discovery provides new knowledge and new theories about how humans developed.
To make it easier to discuss all the different types of plants and animals in the world, scientists have created a system to group living things based on their characteristics. According to this system, humans are grouped with monkeys and apes as well as several other creatures in the primate order. Within that order is a family called the hominids. The term hominid generally refers to modern humans and all of the early ancestors of humans from the time that they began to develop separately from apes. Some scientists include the great apes—gorillas, chimpanzees, and orangutans—in the hominid family as well because of their similarity to humans.
Australopithecines
- Australopithecus afarensis was one of the earliest human ancestors. …
Scientists believe that apes and humans began evolving separately from each other about 5 to 8 million years ago. Fossils show that several different forms of early human ancestors existed before modern humans developed. Among the earliest of these forms was a group known as the australopithecines. It is thought that australopithecines existed between 5 million and 1 million years ago. They were still apelike in that they had large teeth and fur coats and were able to climb easily. Also, compared with modern human brains, the australopithecines' brains were very small. Unlike apes, however, they walked on two feet.
From the many remains that have been discovered, scientists have identified several species of australopithecines. All of these remains were found in Africa. The first of these early hominids to have been discovered was examined by the anthropologist Raymond A. Dart in South Africa in 1924. He named it Australopithecus (meaning “southern ape”) africanus. One of the most famous fossils is that of a partial skeleton known as Lucy. Discovered in Ethiopia in 1974, the remains are believed to be about 3.2 million years old. A set of footprints found preserved in volcanic ash in Tanzania shows that australopithecines walked upright on two legs. These footprints, known as the Laetoli footprints after the site where they were discovered, date to about 3.5 million years ago. Both Lucy and the hominid that left the Laetoli footprints are thought to have belonged to the species Australopithecus afarensis.
Modern humans
- The earliest recognized members of the genus Homo belong to the …
- An ancestor of modern humans known as Homo erectus appeared in East …
About 2 million years ago, hominids began to take on the characteristics of modern humans. Scientists place these later hominids in a different group than the australopithecines. The new classification has the scientific name of
Homo, and individual species of
Homo are given specific names. These hominids were considered separate from australopithecines because they had larger brains and smaller teeth and jaws. Their behavior also became more humanlike. One of the earliest species,
Homo habilis, used stone tools extensively to butcher animals. A later species,
Homo erectus, was the first to use fire. This allowed them to eat a greater variety of foods and to move to colder climates. It is believed that
Homo erectus gradually migrated from Africa into Asia and parts of Europe.
- By about 35,000 years ago, most of Africa, Asia, and Europe were occupied by modern forms of …
All of the early
Homo species either evolved into later species or died out altogether, eventually leaving only
Homo sapiens. This is the species of modern human beings. The species is thought to have developed about 200,000 years ago. How modern humans emerged is a question that scientists are still studying. Some scientists believe that the first modern humans evolved in Africa first and then spread out over Asia and Europe. Other scientists think that modern humans evolved in Africa, Europe, and Asia at the same time, from hominids that were already there.
In addition to physical features, certain aspects of how modern humans live distinguish them from earlier hominids. An early group of modern humans known as Cro-Magnons created the first prehistoric artwork about 30,000 years ago. They carved figures of animals and people and they painted the walls of the caves in which they lived. Some 10,000 years ago humans also progressed from living as wandering hunters and gatherers to living in communities and farming the land.
The last major development in modern humans was the use of language. All primates (apes, monkeys, and humans) communicate in some way. They might use facial expressions, body language, or screams to communicate with others. However, these types of communication are limited. Spoken language allows for feelings and ideas to be expressed, as well as for information about the past and the future to be shared. It is very difficult to determine when humans first developed the use of language. Fossils generally do not reveal any clues as to whether the ancestors of modern humans had developed language. However, evidence shows that written language was being used at least 5,500 years ago, so spoken language must be at least that old. Many questions remain about the origins of language, just as many questions remain about the entire process of human evolution.