Ever wondered what gives redheads their distinct fiery locks?
In its latest Reactions video, the American Chemical Society (ACS) explains the science behind why some of us are born with red hair.
Researchers say its all down to a recessive genetic trait caused by a series of mutations in the melanocortin 1 receptor (MC1R for short) – a gene located on chromosome 16.
Chemically speaking, skin and hair pigmentation is caused by two different kinds of melanin – eumelanin and pheomelanin.
While most humans produce the brown-black eumelanin that results in varying shades of skin colour and hair from blonde to black, redheads have MC1R that causes cells to produce the reddish pheomelanin instead, resulting in paler skin and fiery locks.
As MC1R is a recessive gene trait, both parents need to carry that gene (even if they aren’t redheads themselves) to have a child with red hair.
In addition, it appears the way red hair pigment is produced in the cells also has an effect on sensitivity to pain.
The ACS researchers say studies have shown redheads have higher sensitivity to pain and a slightly greater sensitivity to cold than others in the population.
“Some studies have suggested redheads might need more anaesthesia during surgery as well”, they add.
Although the cause for pain sensitivity has not been determined by the scientists, one of the theories is that MC1R gene expression takes place in the periaqueductal grey area of the brain, which, in part, governs the pain sensation experienced by the human body.