The declaration of the ancient Indian Sanskrit adage “Vasudaiva kutumbakam” (=the whole world is one family) is in concurrence with the findings of the science that infer human beings originated in Africa, who with time upon proliferation, migrated and populated diverse parts of the globe.
The present day global human population presents so many variations in skin, eye and hair colors. Many natural geological processes that affected the Earth have contributed to the mutations in human genes that in turn created new variants in the physical characteristics leading to diversity of human races.
Major volcanic episodes after the origin of human beings like that of Mt. Toba, Sumatra (ca.74, 000 years ago) probably had drastic effect on extant human races. The heavy clouds of dust storms and the nuclear winter that followed the devastating volcanic eruption may have produced serious mutational effects on the physiology and genetic characters of human beings that eventually survived the catastrophe.
Similarly other natural calamities like earthquakes,desertification and migration/diversion/drying up of rivers have influenced human migrations and in turn interactions with differing human groups.
Post LGM evolution of skin colors
The Last Glaciation Maximum (or the Pleistocene ice age) around 10,000 years ago caused drastic lowering of ultraviolet rays in the atmosphere especially in the northern hemisphere. This led to the reduction of melanin pigment in the skin and modification of genetic characters with development of fair skinned people in the cold areas and intermediate colors (ranges of fair to brown shades) in the temperate zones. The melanin content in the skin dictates the color of skin in human beings.
The brown skinned people were developed due to mutation in genes. Polymorphisms in three genes, SLC24A5, TYR and SLC45A2 that are related to the melanin content in the skin collectively account for most of the natural variations of skin pigmentation in the south Asian people. Human skin and hair color is also said to be controlled in part by MCIR gene.
Human skin color is geographically stratified and correlate with environmental level of ultraviolet radiation. Genetic studies suggest that the Europeans and East Asians acquired fair skin colors through different genetic means. The evolution of the light skin post-dates the Ice Age with SLC24A5 and the blue-eye variant of OCA2 both genes showing to significant rise in frequency within the last 10,000 years.
Most of the significant stages in the global human evolution in terms of culture and civilization post date the ice age and by then different colored human beings in different parts of the globe had evolved.
®
No comments:
Post a Comment