Australopithecus afarensis had a very low forehead, a face that projected far forward, and a very prominent brow ridge. A. afarensis is the earliest species for which we have reliable brain and body size estimates. The brain of A. Afarensis was about one-third the size of the average modern human brain, or about the same size as a modern ape's brain. Males and females varied significantly in body size, with males standing approximately 4 feet 11 inches tall and weighing 100 pounds and females standing about 3 feet 5 inches tall and weighing about 62 pounds. Males also typically had large crests on top of their skulls; females did not. The knee and pelvic bone structure of A. Afarensis was very humanlike, meaning it definitely walked upright. A. Afarensis probably inhabited the savannas and open woodlands.