Early Humans: The Origin of Man

Living species are put into classification charts by biologists to determine the relationships among them. We, as humans, belong to a large mammalian family called the Order of Primates; it has many members, both living and extinct, and includes lemurs, monkeys, apes, and humans. Within this order, humans belong to a group known as Hominids, which includes all two-legged, man-like species, whether extinct or living. In this family are extinct erect walking apes, ourselves as humans, and our direct ancestors.

Humans are members of Genus Homo ("Man") and our species name is Homo sapiens ("wise man"). We are sometimes classified even further into a group known as Homo sapiens sapiens. All living humans are members of this subspecies, and even though there are many differences between people in different areas (such as American men and those in another place such as Ghana), all of us are very closely related.

Charles Darwin was the first to present a credible scientific theory of human origins. His famous book On the Origins of Species by Means of Natural Selection, stated that species originated by means of evolution- gradual changes over a long period of time. He said that there were two basic mechanisms at work in this process: variation, which continually occurred within species. This means that individuals of a species differ slightly from one another. He noticed such things as a litter of pups having different traits, or thousands of salmon offspring differing from each other. He also noticed that each individual within a species was not equally identically to another in its means of survival or reproduction. Some individuals were better adapted than others. This drove him to develop the concept of natural selection; certain members of a species will outlast others because their particular characteristics are better adapted to suit the environment in which they live. They would have more offspring as well. Darwin's overall conclusion was that new species came into existence on earth because of variation and natural selection.

Darwin's theory organized vast amounts of biological data collected by other naturalists up until his time. In the late 19th century, researchers combined Gregor Mendel's work with Darwin's theories to provide a better explanation of variation. The discovery of DNA structure in 1956 further confirmed this theory. This solidified Darwin's work as one of the central ideals of modern biology.

Darwin applied his theories to the issue of human origin in his 1871 book, The Descent of Men. Darwin believed that apes and humans must have one remote common ancestor because of their anatomical similarities. He also suggested that the site of human origins was Africa because it was home to gorillas and chimpanzees, which he regarded as our closest living relatives. Fossil discovered ironed out these assumptions. Proconsul africanus (woodland ape) was a gibbon-sized animal that roamed the forests during the Miocene period, roughly 18 million years ago. This creature came about after monkeys and apes had already divided into different types of species. Proconsul appears to be the best match for the origin point of our large family of species. It is most likely the distant ancestor from which all modern species of apes and hominids (including humans) evolved.

Darwin's work influenced a Dutch naturalist by the name of Eugene Dubois to confirm his theories. He believed that humans evolved in tropical Asia; he searched there and found a skull cap and thigh bone which he believed to be in-between apes and humans. He named his findings "Pithicanthropus erectus", or "erect man." The species was later renamed "Homo erectus," or "upright man." Evidence shows that it was the first human-like species to migrate out of Africa and survive in a number of environments, mainly Europe and Asia. Discoveries in the twentieth century confirmed Darwin's theories, and there are now family tree composites that date back as far as 5 million years.

Other species were discovered before Darwin and Dubois' time, such as Australopithecus ramidus, australopithecus afarensis, Australopithecus africanus, homo habilis, and Australopithecus robustus. The next species discovered was Homo erectus, which eventually involved into Homo sapiens, present-day humans. The discoveries made by researchers over the course of many years shaped the history of the human race, and will be further studied forever in the scientific world.