“Cancer may have been instrumental in driving the evolution of black skin in early human history, say experts.
New evidence has led scientists to believe that dark skins appeared more than a million years ago to prevent our African ancestors dying from skin cancer.
The change occurred after ancient humans shed most of their body hair and ventured out into the sun-drenched African savannah.
Previously, like present-day chimpanzees, they would have had pale skin under their hair.
But according to recent findings indicates that the lethal effects of the sun's rays may have exerted powerful selection pressure on early humans between 1.2 and 1.8 million years ago.
Only those individuals with darker, more protected, skin would have escaped dying young from skin cancer and been free to pass their genes onto future generations.
The theory has been rejected up to now because it was thought skin cancer rarely killed people at a young enough age to affect reproduction.
But new evidence points to the fact that albino black people from parts of Africa with the highest exposure to ultraviolet radiation from the sun almost all develop skin cancer and die young.”
And now let's consider if cancer was crucial in changing the skin color from white to black in Africa or other factors affected on the change.
As we know from biology lessons skin under influence of UV radiation produces melanin - dark pigment protecting us against this radiation. Black people's skin contains it more than skin of Caucasian race.
Not only people have this pigment, animals also. It occurs in bodies of invertebrates and vertebrates. I could be a form of an adaptation to environment or a disorder of a disease. A development of the dark-colored pigment melanin in the skin or its appendages is called melanism. We can consider two main kinds of melanism: adaptive and industrial.
As Wikipedia writes about adaptive melanism:
“Most commonly, dark individuals become fitter to survive and reproduce in their environment as they are better camouflaged. This makes some species less conspicuous to predators, while others, such as black panthers, use it as a foraging advantage during night hunting. Typically, adaptive melanism is heritable: A dominant gene, which is entirely or nearly entirely expressed in the phenotype, is responsible for the excessive amount of melanin.
Adaptive melanism has been shown to occur in a variety of animals, including mammals such as squirrels, many felines and canids, and coral snakes. Adaptive melanism can lead to the creation of morphs, the most notable example being the peppered moth, whose evolutionary history in the United Kingdom is offered as a classic instructional tool for teaching the principles of natural selection.”
We will not describe industrial melanism because it is not important in our considerations.
One more effect connected with melanism is that that in cold climate birds with melanism can absorb sunlight and in this way control body temperature without energy wasting.
And now I would like to stop and consider the text above.
If birds with melanism in cold climate can more economically control their body temperature than others so why people do not it in similar way? Why black Africans have not evolved in Siberia only in Africa and dark-colored Indians live in Southern India where is warm climate but more white Indians live in northern India where is colder?
From lessons of physics we know that white color reflects sunlight. For protection against Sun we wear white clothes. So why white people was not created on equator? They would save energy expenditure for body cooling. Nature is not stupid and prodigal. Sometimes it makes mistakes for example Black African - albino but it is exception not rule. And time to time nature tests new solutions so we think that it was nature's mistake but in real it was experiment. I suppose that bright even white pigments exist which could protect skin against hard sunlight as effective as melanin. So why nature has not chosen one of them?
Consider the sentence: ”dark individuals become fitter to survive and reproduce in their environment as they are better camouflaged.”
Is it not a key to the riddle why Black People are black and Caucasians ones - white?
In nature there is a contest between predators and their victims. It could be that skin color was not the reaction for sunlight but for predators and because of natural selection in Africa evolved Black People and in Europe White ones. We can note that in Northern Europe there are white people with clear complexion and blond hair, in a region of Mediterranean Sea - people with olive skin and black hair and next far in the direction of the equator - Black People. Another observation is that in Norther Europe there is a lot of snow, in the region of Mediterranean Sea - snow falls occasionally, but in the equatorial zone, except the top of Kilimanjaro and Mt Kenya, snow does not fall at all. Another important thing is that in the equatorial zone night and day are 12 hours, but on North there is polar night and polar day. During polar night when the sky is without clouds light from the Moon and stars is reflected from sow and it is not totally dark. In Africa, India, Indonesia big cats live who hunt usually during night. In this case white man is excellent target for them. In the final phase of hunting eyes decide about success of the hunt. A nose and ears are good to roughly localize the victim but the final attack cannot be successful without eyes. White man has not chance to hide in darkness. For a Black person it is enough to stop smile to hide white teeth and close his eyes and he is invisible in the dark. So it is easier for big cat to hunt for White men. For big cats would be easier to hunt for people than antelopes because people run much slower. So maybe selection pressure of predators eliminated brighter people from the equatorial zone.
Another situation we have to the North where gray wolf lives. In Europe, especially Norther Europe gray wolves dominated. Their main food is small animals like hares, badgers and also deers and roes. They were especially aggressive during winter when they have not enough food and because of cold they had to eat more. So probably very good victims for them were human beings. Of course wolves have excellent noses but to the final attack they must see the victim. So in this case Black person is excellent visible on snow. So probably in the northern region of our plane selection pressure promoted white complexion.
And what about people with intermediate skin color from the region of Mediterranean Sea?
Probably there extreme skin tones were eliminated because prides of lions and packs of wolves who drove up to this area. In this zone it is a little snow so probably it was the safest for people to have intermediate skin color.
Fallowing this clue we can consider why Black people from USA or Jamaica who are descendants of Black people from Central Africa run excellent sprints and Black people from Eastern Africa: Kenya, Ethiopia run long distances good. But usually White people are losers in these competitions. I am thinking about a general tendency, not about some special cases. Here could be explanation: climate and predators. When lion attacked a group of people she followed them maybe 400 - 800 meters and caught the slowest one or stopped hunt on them. So the slowest people were eliminated.
Regarding to residents of East Africa, poor in water and forests, I have this working hypothesis. A group of people, who ate everything what was eatable in one area should find quite fast another place rich in water and food. These places were separated by vast savannas. Being in the open area during day and without water threatened death. Probably people moved during night running because of two reasons. First one - before dawn they should proper wooded area rich in water and food and the second one - running shorter time they were exposed to attacks of big cats.
Running people overcame long distances and again selection pressure saved only the best adapted it means the best long-distance runners.
In Europe, the case was differently. Escape from wolves on foot through the snow was doomed to fail. Only salvation was climbing a tree, hiding somewhere in the snow or cross-country skiing. The oldest found ski are around 8 thousands year old and probably the discovered ski are not the oldest ski which was used in the world. The oldest ones are not discovered yet or did not survived to our times. In skiing white people win despite the fact that Black people or Indians live in Europe or North America and have the same opportunities to practice skiing as White people.
So my assumptions may prove to be true.
For a summary of my reflections I would like to ask why scientists seriously consider the hypothesis of cancer which leaded to change color of skin from white to black but do not consider the hypothesis of predators as selection pressure used by nature to evolve black and white skins with some intermediate colors?
Is it possible that political correctness does not allow them to research the influence of predators on human's skin color?