No. 15, a strikingly tall man with side-swept bangs, says: "I want to get married for my parents, but I think lying to them will make me feel terrible.

So the gene could have been favored because it conferred protection against some disease, with thicker hair being swept along as a side effect.

It covers the moon's leading hemisphere - the side that faces forward as it moves in its orbit - which suggests that the black material has been swept up from space as the moon moves around Saturn.