People with red hair and light skin can be considered winners from an evolutionary perspective. According to a large-scale genetic study published in the journal Nature, active natural selection for the red hair gene has been ongoing in Europe for more than 10,000 years.
By analyzing the DNA of approximately 16,000 ancient human remains and more than 6,000 modern individuals, Harvard University scientists have proven that human biological evolution continued at a high pace even after the development of agriculture.
What evolutionary factors led to the preservation and spread of genetic variants for red hair and light skin?
Scientists identified nearly 500 genetic variants that have become increasingly common in our recent history. In addition to red hair and light skin, natural selection favored genes that reduce the risks of balding, diabetes, and rheumatoid arthritis.
Researchers suggest that red hair and light skin are survival mechanisms for northern climates. This skin type produces Vitamin D much more efficiently under low-light conditions, which was critical for people whose diets were poor in this vitamin.
The Strange Advantage of Diseases
The study also revealed paradoxical trends. For example, the risk factor for Celiac disease (gluten intolerance) emerged 4,000 years ago and has been spreading ever since. Despite the autoimmune risk, individuals with this gene had a higher chance of survival. Presumably, this variant protected them from other infectious pathogens of that period.
A similar pattern emerged regarding Tuberculosis. A gene that significantly increases the risk of this disease actively proliferated between 9,000 and 3,000 years ago before beginning to decline again.
Another Interesting Finding of the Study
In the past, when humans obtained food through hunting and gathering, the ability to store fat (so-called “thrifty genes”) was vital for surviving periods of famine. However, as soon as humans turned to agriculture and food supplies stabilized, storing excess fat was no longer necessary. On the contrary, it led to health problems, causing natural selection to strip away the advantage from individuals carrying these genes.
