Compared to many other species, all humans have incredibly similar genomes. However, even small changes in our genes or our environment can lead to some very unique traits being developed. Sometimes these differences manifest themselves as a change of hair or eye color, but other times it’s something way cooler and more significant.
Here are some genetic quirks you didn’t realize were normal.
1. Red Hair
Although seemingly everyone has a soulless ginger friend, this hair color occurs only in 4-5% of people. In Northern Europe, redheads are born more often, making some researchers believe that such mutation is a genetic response to the lack of sun, shorter days, and longer nights, but nobody knows for sure. It could very well just be the lack of negative selection that removes unnecessary mutations.
2. Lactose Tolerance
Lactose tolerance is one of the finest examples of human evolution that is now being actively discussed. While milk is considered commonplace among modern humans, other mammals stop drinking it when they reach maturity because they lose the ability to digest it. Ten thousand years ago, Europeans began to domesticate cows. During that period, a mutation has occurred, allowing some people to continue producing the necessary enzymes that make drinking milk safe for us. Well, for most of us.
3. Blue Eyes
Although only about 8% of the world’s population has blue eyes, the mutation that gave rise to this beautiful feature is incredibly old for our species. The first blue-eyed person lived in Spain seven thousand years ago. Prior to that, everyone had brown eyes, but researchers have established why they turned blue. The gene responsible for the amount of brown pigment produced by the iris was turned off, resulting in cool blue eyes.