Leaf clipping is a behavior that has been observed in different chimpanzee populations.
This behavior is an intriguing one because in all populations,
the chimpanzees would take a leaf like that and, holding it in the central petiole,
would put that in the mouth and rip little blades of the leaves away
and do like me--eat nothing of it.
It just produces a sound of being ripped.
That is leaf clipping.
So why would chimpanzee bother doing something where they don't eat?
And what came out is that actually in the Mahale--chimpanzees in Tanzania--
when they do that behavior, it's to attract the attention of sexually active females.
And, it's only done by males.
So it's a sexual courtship kind of behavior.
If a chimpanzee in Thai Forest does that, it's also a male,
but he does it when he prepares to do a drumming sequence.
So he's alone in front of his buttress tree, and he's doing this leaf clipping
and then will do the display on drumming.
And when you are in Bissau--which is in Guinea, it's 250 kilometers away from Thai Forest--
the chimpanzees would do that--the same behavior again, but it's to attract a play partner.
So we have here exactly the same behavior with the same form, but it has acquired a social meaning.
And this meaning is in each group different.