Red-haired women, but not red-haired men, are more sensitive to pain

Red hair is also associated with a higher risk of developing endometriosis, Parkinson's disease, and decreased platelet function. A new study has confirmed that red hair, especially in women, is linked to certain health issues. In a sample of over seven thousand participants, red-haired women did worse than other women in ten health categories and better in only three, being especially prone to colorectal, cervical, uterine, and ovarian cancer. Red-haired men seemed as healthy as other men, doing better in three categories and worse in three. Reproductive success, i.e., number of children, was the only category where redheads of both sexes did better than other respondents. This study has also confirmed that red hair is naturally more frequent in women than in men. To a lesser degree, the same is true for blond hair and green eyes. These bright colors seem to result from a selection pressure that mainly targeted women, perhaps sexual selection.