Someone with red hair has two copies of the MC1R gene, receiving one from each parent. The gene also carries a certain mutation in most people who have red hair. It's this variant that has been identified as playing a role in why redheads may respond to pain drugs differently than others.
Here's what studies have revealed about redheads and pain: They need about 20 percent more anesthesia to be sedated. They also need more local topical anesthetics, such as lidocaine or Novocain, which is why many redheads have a fear of dentists, according to the American Dentistry Association.
Humans and mice with red hair have a different tolerance for pain because their skin's pigment-producing cells lack the function of a certain receptor. Lack of this receptor function causes changes that tip the balance between pain sensitivity and pain tolerance.
Final Thoughts on Redheads and Alcohol Tolerance
There's not enough evidence to claim redheads have a higher tolerance to alcohol than other people. However, several social and genetic factors (including the MC1R mutation) may lead to a perception that they have a high tolerance and a predisposition to alcoholism.
The skin of a redhead is thinner compared to others and is derived from the ectoderm. Teeth enamel is also derived from the ectoderm and thus is thinner than usual. Since the enamel coating is thin, the inner layer of tooth-dentin is more visible and offers a yellowish appearance.
“Red hair and blue eyes are both recessive traits which means a person needs to inherit both of the genes for red hair and blue eyes, from both parents. In contrast, brown hair and brown eyes are dominant traits, which is why they are much more prevalent.”
Some evidence suggests redheaded adults often appear older than their actual age. For example, one study published in 2016 in Current Biology found that adults who carry two copies of the MC1R gene variant are more likely to look two years older than other people their age.
The conclusions come from a survey of 10,878 white Americans asked about their natural hair colour (Hispanics and African Americans were excluded to eliminate bias). The results showed the average IQ of blonde-haired women was 103.2, 102.7 for brown hair, 101.2 for red hair and 100.5 for black hair.
This is because of a specific gene connected to redheads – the MC1R gene. This gene makes the individual more sensitive to touch than people with other hair colours.
This is to be expected because red hair is associated with fair skin, which is more vulnerable to UV radiation [1]. Less expectedly, red hair is also associated with pain sensitivity, endometriosis, Parkinson's disease, decreased platelet function and, perhaps, defects in the immune system [2–11].
Fun facts about red hair strands
Redheads are less likely to go grey. The pigment in red hair typically fades over time from red to blonde and white, but not grey. Redheads produce more Vitamin D in a shorter amount of time than people with other hair colors.
This was followed by a small study published in the journal Anesthesiology, which found that women with red hair required up to 20% more anesthesia to keep them sedated than did women with dark hair.
Their findings showed that redheads required more anesthetic to block their movement and responses to pain, compared to women with dark hair. This lines up with anecdotal evidence from anesthesiologists and doctors, who claim that redheads need more anesthesia to “go under'' during treatments.
People with red hair also respond more effectively to opioid pain medications, requiring lower doses. People with red hair have a variant of the melanocortin-1 receptor (MC1R) gene. This gene controls the production of melanin, the pigment that gives skin, hair, and eyes their color.
A study headed by Dr. Edwin Liem at the University of Louisville in Kentucky found that redheads are more sensitive to hot and cold, and are hurt by the cold at temperatures nearly 11 degrees Fahrenheit warmer than others.
Contrary to what many people assume, redheads did not originate in Scandinavia, Scotland or Ireland, but in central Asia. Their coloring is due to a mutation in the MC1R gene that fails to produce sun-protective, skin-darkening eumelanin and instead causes pale skin, freckles and red hair.
One of the many facts about redheads is that their hair will never turn grey. The pigment in their hair that causes it to be red will just fade over time, causing their hair to turn blonde or white, but never grey.
Less than 2 percent of the world's population has red hair, making it the rarest hair color in the world. It's the result of the mutated MC1R gene. If both parents carry that gene, their child has a 25% chance of getting lovely, red locks, even if the parents don't have red hair themselves.
According to an article by evolutionary biology professor Mark Elgar, PhD, of the University of Melbourne, blue-eyed redheads are the absolute rarest, with 0.17% of the population having that combination of hair and eye color.
Lifespan: up to 20 years in captivity, 5-10 years in the wild.
Redheads feel hot and cold temperatures more severely than anyone else. In 2005, the University of Louisville discovered this hidden gift and hypothesised that the redhead gene, MC1R may cause the human temperature-detecting gene to become over-activated, making redheads more sensitive to thermal extremes.
Researchers think that the ginger gene, known as MC1R, may cause the temperature-detecting gene to become over-activated, making redheads more sensitive to the cold.