Everything in us is in our DNA.
When we think about the topology of the DNA and its connections with climate and environment we must realize that our bodies and our cells cannot match with all types of environment. Things like chemical environment and animal poisons can also affect things which skin color is the best. If animals like snakes are creating white poison, the black skin is better. But if the major toxic agent is black that thing is easier to see from white skin. Also, things like blood leaks are better visible on blond skin.
Genetic adaptation makes African people black because dark pigment protects cells against sunlight. But why do northern people have white skin? The reason for that is in the environment, at spring the snow and sun create scattering light and the dark skin cannot protect cells against powerful UV light. And also dark skin can cause situations.
Where cells are overheating in changes of temperature. In cold weather, people must protect themselves against the environment by using strong clothes. When we are looking at images of people around the world people who live in stable temperatures have black skin.
But people like Beduins and Europeans have blonder skin than people who live in stable temperatures. The temperature changes very much during the 24 hours. And if the skin is black. The temperature can rise in cells very fast. And it can cause damage. The white skin is better in the case where cells must let radiation travel through it to stabilize temperature in them. But white skin lets UV radiation travel the DNA. That means there is no perfect skin or perfect genomes.
The same thing that can make people adapt to certain environments is the risk in another environment. There are also many other things than just radiation that can cause cancer and affect the ability to survive. The cancer is not the only thing that the wrong genome can cause. Genetic disorders can deny the ability to get descendants. Or it can cause the situation that the creature cannot find food. Whenever a life circle is changed that thing forms a mark in the DNA.
Skin color is the most visible example of genetic adaptation. But things like the ability to produce red blood cells are the things that are necessary for people who live in high areas. That thing causes problems with cancer, because if cells are splitting too often. There is the possibility that a person gets leukemia because of endemic carcinogens stress. Whenever a cell divides it has a higher risk of getting a mutation.
