Darwin Skin Color

One of the most revolutionary figures of evolutionary history, Charles Darwin, knew that skin color was one of the most important ways that people varied. However, he never wrote about these variations in The Origin of Species. In his 1871 work, The Descent of Man, he wrote, “Of all the differences between the races of man, the colour of the skin is the most conspicuous and one of the best marked…” Darwin however, rejected the idea that human skin pigmentation was related to climate. Today, we know that darkly pigmented people are found near the equator and lightly pigmented people are found nearest the poles of Earth. The earliest humans evolved in high UV regions of equatorial Africa. UVB radiation is very important in the production of vitamin

Number, size, and distribution of melanosomes in the epidermis, the outer layer of tissue, is largely responsible for skin color. Melanosomes store and transport melanin which is the most common light-absorbing pigment found in humans. Melanin reflects and absorbs light that allows us to see the different types of skin color. There are two different types of melanin: pheomelanin, which is a reddish yellow and eumelanin, which is brownish black. Exposure to too much ultraviolet light can cause mutations within skin cell DNA. However, melanin protects DNA by forming super nuclear caps that absorb the UV light. As humans evolved, we lost the hair covering our skin which led to an increase in the production of melanin. UV intensity predicts skin color; the darkest pigmentations are found near the equator or high altitudes while light skin pigmentation is found in areas far from the equator. MC1R, the melanocortin one receptor gene, is closely linked to skin pigmentation and hair color. However as seen within the African population, there is little diversity of this gene which leads to little variances of skin color and hair color in that population. MC1R has much wider variation among European and Asian populations due to the fact they are more lightly pigmented groups which is shown by the many variations of skin and hair color of

Once homo sapiens began to spread across the globe, pigmentation was subject to many evolutionary forces: new environmental pressures, mutation, drift, and sexual selection. Hundreds of thousands of years of human evolution and new and changing environments are key to New World population variance of skin pigmentation. Skin coloration is highly adaptive and has evolved to the needs of humans as they have spread across the Earth. Differing regions of Earth receive different amounts of UVMED which leads to the types of melanin produced by the skin. Darker skin with more melanin is needed to protect folate and sweat glands in humans. UVMED is more concentrated nearest the equator which is why darker pigmented people are found in that region. In areas of low UVMED, adaptations occur over, relatively speaking, short periods of geologic time. Skin pigmentation has no relevance when assessing phylogenetic relationships among human groups due to the fact that human skin pigmentation is determined by the amount of UVMED in one’s environment. UVR has direct and indirect effects on one’s reproductive fitness. Populations who have inhabited their current environment for about 10-20,000 years follow the predictions of skin pigmentation closely, those who recently migrated to their current area show less relation of predicted skin pigmentation. Cultural practices have also had significant influence on the determination