More Australopithecine
On Shelf #1: Between 3 to 2 million years ago, perhaps in response to changing climate conditions, some australopithecine groups adapted to a new more arid, harsher environment by eating harder and tougher foods. As you can see in these skulls of species that some refer to as “robust australopithecines”, jaws and teeth as well as the bony structures of the face that supported the much larger chewing muscles needed for the new diet became larger. There are two specimens displayed here both discovered by teams led by the Leakey family of Kenya. On the left, the so-called “Black Skull” KNM-WT17000 (Paranthropus aethiopicus [found in 1985 by Alan Walker in the West Turkana region of Kenya; ~2.5 Mya]), which acquired its dark coloration from the high amount of manganese in the surrounding earth, and on the right, originally placed in the now-defunct genus “Zinjanthropus” by it’s discoverer and so nicknamed Zinj (Paranthropus boisei [found in 1959 by Louis and Mary Leakey in Kenya’s Olduvai Gorge; ~1.5-2 Mya]).
• The nickname “Zinj” is an Arabic word meaning “East Africa”, probably itself derived from “Zanzibar”, an island that is now a part of the country of Tanzania, and that was a central hub in the Indian Ocean trade network of Muslim traders for centuries.
• Note the sagittal crest, the ridge of bone that runs across the top of the head. This is where one set of chewing muscles from the lower jaw (the temporalis muscle) attached to the skull. Also note the exaggerated size of the cheekbones, there is another set of chewing muscles (the masseters) from the lower jaw that attach there.
• You can feel on yourself where those chewing muscles attach to the face and skull in modern humans. By comparison, our muscles are very small. The temporalis in modern humans attaches just above the ear. You can feel them working by placing your fingers just above your ears, while opening your mouth widely and then closing and clenching your jaws. You can feel our masseter by placing your fingers at your cheekbones and moving your jaws open and closed. (Why do you think the muscles of chewing in modern humans have become so small?)
