The researchers discounted two theories commonly put forward to explain protruding brow ridges: that they were needed to fill the space where
the flat brain cases and eye sockets of archaic hominins met, and that the ridge acted to stabilise their skulls from the force of chewing.
One display
case contains the casts of an array of hominid skulls: the robust, massive - jawed 1.6 - million - year - old Paranthropus robustus from Swartkrans, South Africa; the
flat - faced 1.7 - million - year - old Paranthropus boisei from East Turkana, Kenya; the tiny skull and fossilized
brain of the 2.5 - million - year - old Taung child, or Australopithecus africanus, found at Sterkfontein, South Africa.