If your friends are always drinking you under the table or you remain sober long after all your drinking pals have achieved a buzz, don't blame yourself. Don't blame your weight or muscle mass. Don't blame your experience at the bar or lack thereof. Blame your eyes.
According to several recent studies, eye color is a pretty good indicator of alcohol tolerance (along with pain tolerance, risk for diabetes, and hand-eye coordination). Congratulations, blue eyed drinkers, you can hold your liquor better than your dark eyed peers. We’re just not entirely sure why yet.
One possible culprit is melanin, the pigment that darkens brown eyes. A study from Georgia State University found that more melanin would make people more susceptible to the effects of alcohol, increasing responsiveness to booze in terms of “perception, reaction time, motor skills, personality and physiological reaction.” The researchers had a few suggestions for the cause behind this difference. On the one hand, melanin could speed up neural transmissions in brown-eyed people, firing alcohol’s effects into the brain faster. Alternatively, the endocrine system, which controls hormones responsible for all sorts of bodily functions, could respond differently to light waves that do or do not enter the eyes depending on eye color. In either case, the less melanin in your system, the more drinks it takes to feel the booze.
Meanwhile, researchers from the University of Vermont, who compared alcoholism rates among people with different eye colors, suggested genetic sequences determining eye color and love of drink were neighbors on the same chromosome. Given that eye color doesn’t derive from one single gene but variations in 12 or 13 of them, it seems entirely possible there would be some genetic overlap between alcohol responsiveness and eye color.
Whatever the reason, when it comes to how you hold your booze, you definitely can believe your eyes.