Heba Medhat
Delving into life’s origin and human evolution, the piece examines theories such as Darwin’s natural selection, genetic drift, and microevolution. It discusses the evolutionary progression of the Homo genus and homology among apes and humans. The article also underscores challenges in Darwinian evolution, making it a compelling read for those interested in the complexities of human evolution.
Human Evolution?
Even though technological advances have helped researchers understand the functions of the basic structures of human life, debate continues regarding how life on earth originated. Various scientific fields from anthropologists to biologists have wide ranging disagreements as to the length of time that brought life on earth to its current form to the methods that affected life as we know it.
These ongoing debates underscore one basic fact; no one knows the truth of how life began on earth. Did all life spring from a common single-celled life form millions of years ago?
Charles Darwin (1809-1882) is often considered the father of modern evolutionary thought. He conjectured that all types of organisms arise and develop through the process of natural selection of inherited mutations that increase the individual's ability to compete, survive and reproduce even in men. In natural selection, if a population faces conditions of hardship, some organisms may have a helpful trait that allows them to survive that hardship and pass that beneficial trait to offspring.
Darwin's observation for the theory:
For any species population sizes would increase exponentially if all the individuals that are born reproduce successfully
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Members of a population vary extensively in their characteristics, most variation inherited
Darwin's hypothesis is that natural selection was the mechanism for differential reproductive success
Although Darwin’s observations on natural selection can be explained through variations within a species, this observation does not show movements from one species to another through genetic modification and there is no evidence that a line of rabbits, for example, eventually become a species of squirrel.
The lack of evidence to support Darwin’s speculations have given rise to other evolutionary concepts, such as genetic drift which produces random changes in the frequency of traits in a population. For instance, when people who have the gene causing a specific genetic trait, like freckles, reproduce with people who do not have the gene. Microevolution refers to changes in the gene frequencies in a single population over relatively short periods of time. According to the Wion Web Team, in “Human ‘microevolution forming more arteries, less wisdom teeth in babies,” scientists have found that babies are now being born with a slightly smaller jaw and extra bones in their legs and feet.
Holly M. Dunsworth, in, “The Origin of the Genus Homo,” found that a generally accepted model of the evolutionary progression of humans is based on three different branches “Macroevolutions.” Homo (H.) habilis is known for being the first stone tool makers. H. erectus was the first obligate, fully committed biped and with a body adapted for modern striding locomotion, H. erectus was the first in the human lineage to disperse outside of Africa. H. radolfensis had a relatively large brain and large teeth compared to H. habilis. The relationship among H. habilis, H. rudolfensis and H. erectus is not very clear. Some scientists think that H. habilis was the ancestor of H. erectus, but others disagree. Some also suggest that H. habilis and H. rudolfensis are different sexes of the same species.
Among Apes and humans, homology exists which means similarity in physical structure. The embryological structure shows the conservation of homeotic and they are genes that control body formation. Molecular Homologies include genes, proteins, and protein products, shared among organisms inherited from a common ancestor. Similar structure means similar DNA which means similar ancestry.
In fact, there are problems with Darwinian evolution; there are no fossil records supporting Darwin; the failure of biological evidence, and the failure of Chemistry to provide Genetic code.
Chimpanzee blood has similar traits to human blood. They have A, B, AB, and O. However, chimpanzee blood cannot be used for human transfusions because chimpanzee and human blood differ in too many details that still need to be investigated.
Humans have one pair of chromosomes fewer than monkeys. This similarity in the genome made some scientists believe in the possibility of hybridization between humans and chimpanzees, which might result in a new creature called (humanzee). In the 1920s, the Russian biologist, Ilya Ivanovich Ivanov, was very interested in human-chimpanzee. He managed to get support from the Soviet authorities and the Pasteur Institute. He went to the primate center in French Guinea, he succeeded in impregnating three females with human sperm. But none of the three females became pregnant.
Some other sources mention the occurrence of hybridization experiments between monkeys and humans in China in the sixties, and this time, after fertilization, a female monkey became pregnant, but without this pregnancy being completed. It is also reported that another attempt was made in the United States in the 1920s. Where not only did the female chimpanzee become pregnant, but she gave birth to a live baby, the scientists did not keep it.
Oliver
And in the 1970s, a super-intelligent monkey named Oliver sparked a lot of rumors. Where it was said that this chimpanzee, which was performing in the circus, was the product of a human and a monkey. Because of his strange behavior, suspicions increased. But tests on the genome showed that Oliver had the same number of chromosomes as any other monkey. Oliver had light-colored eyes that were also unusual for an ape. He was comfortable as a biped and walked like a man naturally.
There are still debates about Homo genes which prevent a consensus on what constitutes the Homo genes. There are no new discrete anatomical traits that appear or disappear in Homo. As a result, there is a disagreement regarding the attribution of the habilis and rudolfensis materials.