Chimpanzees graying differently than people: number of the bleached hair they grow to middle age, then plateaus. This means that gray hair cannot be used as a marker of aging. To such conclusion the team of scientists analyzing photographs 145 wild and captive chimpanzees. As noted in an article for the journal PLoS ONE, humans are the only mammals for which proven link between age and gray hair.
Gray hair in people is one of the most obvious signs of aging. Gray and some other mammals: for example, gorillas (Gorilla spp.) silver back males indicates their sexual maturity. While it still remains unknown whether there is a relationship between loss of pigmentation of hair and aging in any animal except man. Even gray Pets considered rather a symptom of stress than age-related changes.
Team primatologia headed Tapanes Elizabeth (Elizabeth Tapanes) decided to explore this question on the example of chimpanzee (Pan troglodytes), which often appear gray hair on the head, primarily on the chin. Gray chimpanzees can actually be considered old, however, there is no unequivocal evidence that they are turning gray as well as people.
Experts analyzed photos of the wild and 145 captive chimps aged up to sixty years. The selection included data on representatives of two subspecies: the Western (P. t. verus) and Eastern (P. t. schweinfurthii). Then a large group of volunteers (in total 152), unfamiliar with the depicted in the photographs of chimpanzees were asked to assess the degree of gray in each photo on a six-point scale.
People have gray hair sometimes affects all the hair on his head. In contrast, among the studied chimpanzees no individual imaging studies have got six points, that is, not gray, and only one came close to five points, corresponding to 80% non-pigmented hair. Although the share of gray hairs varied greatly from specimen to specimen differences between the genders and representatives of different subspecies were found.
The authors failed to reveal significant correlation between graying and the age of the chimpanzee (p = 0.382). Unlike humans, these primates share bleached hair was growing from year to approximately twenty-nine years before middle age. But then she went on a plateau at the level of sixty percent or higher and the aging does not increase. People have gray hair develops absolutely not: we continue to put the rest of your life.
There are several possible explanations why chimpanzees never fully gray. Perhaps the dark color of their hair has adaptive value, for example, is used for thermoregulation. In addition, gray can distort the appearance of individuals and complicate their recognition in the group.
Thus, the gray cannot be used as a marker of the age of the chimpanzee. This feature is suitable only to very roughly to separate individuals under the age of thirty years older. But man is the only species characterized by the relationship between aging and the amount of gray hair.
Age is not the only reason due to which the hair people lose color. According to a recent study, gray also comes from the strong stress. But if the stress level is reduced, the hair can restore the previous color.
Sergey Knee High