Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [70]
He contrasted the australopithecine’s arms and hands with those of modern apes. Modern apes possess long arms and long hands, with long palms, long fingers and short thumbs, developed so that they can suspend themselves beneath branches and move by arm-swinging from branch to branch. When walking on the ground, they use their long arms as supports and walk on their knuckles. By comparison, human ancestors like australopithecines never went through a knuckle-walking stage, but instead retained a primitive hand that was specialised only in its opposable thumb for branch-grasping.
‘It was this long opposable thumb and relatively short palm and fingers that provide the necessary manual ability for tool-use and toolmaking’, said Clarke. ‘It is the combination of this hand and the large complex brain that has enabled humans to develop into the only advanced cultural animal on earth’.
The cave systems in the Sterkfontein area continued to yield spectacular finds. In 2008, a research team led by Lee Berger, a palaeontologist at the University of the Witwatersrand, discovered the first of four fossilised skeletons in a pitlike excavation at Malapa, once part of an ancient underground cave system about 150 feet deep. The Malapa fossils—two adult females, an adolescent boy and an infant—were found within a few feet of each other, suggesting they had died at the same time or soon after one another. The theory was that they had probably died after falling or climbing down a vertical shaft leading to the underground cave system. Within days of their death, a sudden rainstorm and mudflow had washed their bodies—along with the bodies of sabre-toothed cats, hyenas, wild dogs and horses—into a deeper, waterlogged recess where they were encased in calcified rock.
The fossils were dated about 1.9 million years old. Living on the cusp of the emergence of Homo, they possessed a mixture of features: Some were modern, with small teeth, long legs, projecting noses, advanced pelvises; others were archaic, with long arms and small brains. Berger’s team decided they should be assigned as australopithecines rather than to Homo and gave them the name Australopithecus sediba—a Sesotho word meaning ‘fountain’ or ‘wellspring’.
Announcing the finds in 2010, Berger followed the long tradition among palaeontologists of making grand pronouncements about their field discoveries. ‘We do feel that possibly sediba might be the Rosetta Stone for defining for the first time just what the genus Homo is’, he said.
Mary Leakey, seen here at Laetoli at the end of a trail of hominid footprints fossilised in volcanic ash. The trail dates from 3.6 million years ago and shows that hominids had acquired the upright, bipedal, free-striding gait of modern humans by that time.
A single adult footprint from the trail at Laetoli. The footprints show a well developed arch to the foot and no divergence of the big toe.
Mary Leakey at work with the American palaeoanthropologist Tim White during excavations at Laetoli in 1978.
Donald Johanson and Tim White announce the naming of a new hominid species Australopitchecus afarensis in 1979, provoking a furious controversy.
Proconsul africanus: The reconstructed skull of a Miocene era primate discovered at Rusinga Island, Kenya.
The Taung child skull—Australopithecus africanus—discovered in 1924.
An Australopithecus robustus skull discovered at Swartkrans, South Africa, in 1949.
Nutcracker Man, or Zinjanthropus boisei, a robust australopithecine discovered at Olduvai by Mary Leakey in 1959.
A Homo habilis skull found in East Turkana, Kenya, in 1973.
A collection of hominid fossil skulls, together with femur and tibia fragments, found at East Turkana. The skulls are: a Homo habilis specimen known as 1470 after its classification number (centre); Australopithecus africanus (bottom); and Australopithecus