Along with the increase in skull size, the shape of the skull also suggests enlargement of the brain and of the frontal lobe in particular. Australopithecine skulls do not look much different from ape skulls. There is a prominent jaw, a small sloping forehead and a relatively small brain casing. Modern humans, in contrast, have flatter faces, very steep foreheads, and small jaws. Our foreheads, which lie just in front of the frontal lobe, cover about 50 percent of our faces. Likewise our brain casing is greatly enlarged relative to the rest of our skull.