The Evolution Of Humans Essay Sample

Evolution involves the change of inherited characteristics of biological populations in successive generations. The process give rise to different levels of organization and diversity that includes changes in DNA, species, molecular formations, and the basic proteins forming the organism. Human evolution has been a major subject both in history and biology. Many theories have been advance explaining the origin of man on earth. The most prominent of the theories is the Darwin’s Theory on human evolution.
Darwin theory of evolution is based on natural selection. The theory explains how the environmental factors and other factors interact to favor or not specific species that leads to natural extinction of some species, and eventual progression of the others. There are some basic facts on the Darwin’s theory. These include the following; first, more off springs are produced by particular species than they can possibly survive. Secondly, the offspring’s adapt in varied manner leading to difference in reproduction and eventual survival. Thirdly, the difference that emerges in the process of adaption and reproduction are heritable. The evolution does not change an individual but changes the whole of the population. It is based on these facts that naturally the species are filtered allowing only those that are fit to survive in the changing environment. Functional roles are defined. Mutation and genetic changes also occur.
Gene mutation involves the changes in the DNA sequences of the cells. The results of gene mutation affects or does not affect the overall genetic make-up of the species. If the mutation leads to changes in the proteins, the results are harmful. Gene mutations evolve within the specific gene families from a common ancestor. In the process of gene mutation, the new genes may acquire new functions, while the original genes perform the original functions. The overall effect is a complex species that is superior to its ancestor. Biased mutations lead to different species even when the ancestor is common. This happens if mutation occurs in one of the species belonging to ne family while the species do not experience mutation.
Based on this theory, humans evolved from primates of the genus Homo. It is established that during the late Cretaceous period i.e. about 85 million years ago, the primates diverged from other mammals with the earliest recorded fossil appearing in the Paleocene period (55 million years ago). Between 15 and 20 million years ago, the Hominidae diverged from the Hylobatidae. The Ponginae commonly known as the Orangutans diverged from the family Hominidae about 14 million years ago. The main adaptation characteristics of the Hominin were bipedalism. The initial bipedal Hominin were the Sahelanthopus, Orrorin and the Ardipithicus. Later, the Australopithecus of the genus Homo evolved. About 2.3 million years ago, the first member of the genus Homo i.e. Homo habilis evolved. The brain size of Homo habilis was equal to that of the chimpanzee. It has been suggested that during this period, the human SRGAP2 gene doubled and wired the frontal cortex of the brain.
With the 1 million year that followed the process of encephalization began leading to emergence of Homo erectus whose cranial cavity had doubled. Home Erectus evolved to Homo heidelbergensis, followed by Homo antecessor who were found in Africa. The Homo antecessor evolved to Homo neanderthalensis, and finally in to archaic Homo sapiens between 400, 000 and 250, 000 million years ago. There was little interbreeding between these species. The modern Homo sapiens came to being about 50,000 years ago as many anthropologists suggest. Evidence on such progression is based on fossils found in East Africa.
The adaptation process led to the bipedalism of humans today. Adaptation makes an organism fit in the habitat. The process of adaptation proceeds from natural selection. The process o adaptation leads to either gain or loss of ancestral features. It is based on this fact that current men are less hairy than there common ancestor the chimpanzees. The tails has since become vestigial due to its lack of purpose while it still remains with the chimpanzees. The human teeth have also adapted to soft foods that have been softened by cooking as opposed to what was the case before.
Knowledge on human evolution is crucial today in certain ways; it serves to satisfy human curiosity of his origin. It also offers the best insights on the characteristics of the humans today. Some of the tools used today have their ideology rooted back in the ancient times of the early, middle, and late Stone Ages. Such knowledge has been used in the identification of the chimpanzee in medical tests.
The natural history museum has been one of the key museums documenting human evolution. The museum explaining details the origin of different species human being included. The museum has been displaying reconstructed skulls obtained by archeologists and other scientists involved in the study of species’ evolution. Most of the modern findings on the origin of man are documented in details in the natural history museum.