 This grooming behavior involved one chimpanzee taking hold of the hand of another and lifting it into the air, allowing the two to groom each other's armpits.Though this would seem to make grooming of the armpits easier, the behavior actually has no apparent advantage.As the primatologist Frans de Waal explains from his later observations of the hand-clasp grooming behavior in a different group of chimpanzees, "A unique property of the handclasp grooming posture is that it is not required for grooming the armpit of another individual...