Cavemen

To see the family of monkey people on Sierra 117, go just past the point where Johnson's Pelican gets shot down; you will see a concrete column with the number 3 on it. Stay beside the left wall and go as high as you can. When you reach a point that you have to drop down to the ledge that the Jackal with a Carbine is/was standing, turn around.

The Monkey People are right there against the wall.