Conversation between two apes explained

My chimp/chump story from last week is a simplified example of how one ape species split into two.  This splitting is called speciation.  The apes in the story are members of the species that was the most recent common ancestor of humans and chimpanzees (and bonobos.)

Let’s pause for one of the digressions I like to [...]

A conversation between two apes

A1:  Hey, man.  I’m hungry.
A2:  Me too.  There isn’t enough fruit any more.
A1:  That’s because there aren’t enough trees.
A2:  There should be some fruit in those trees over there.
A1:  Are you crazy?  How are you going to get past the tigers?
A2:  Run.
A1:  Run?  On what?  Your legs, ankles, feet and hips are adapted for swinging [...]