You can tell how old a male giraffe is by looking at its spots, according to a new study. Researchers looked at 33 years of data on Thornicroft giraffes in Zambia and discovered that the level of darkness of the animal's brown blotches reveals its age, reports BBC Nature. "The main contribution of our work is that we could attach specific ages to coat color changes, which provides something of a 'biomarker' of aging in giraffe," says a Kyoto University scientist.
The shift in shade of the giraffe's fur could be due to changes in testosterone during puberty, he adds. "I suspect that the blackening of the blotches is a public announcement to the other giraffe that a male is going through puberty, something like adolescent boys flexing their muscles to impress the opposite sex."