Born in Africa_ The Quest for the Origins of Human Life - Martin Meredith [68]
‘Early hominins may have climbed trees like modern humans can and occasionally do today; however, this study suggests that vertical climbing and arboreality were not significant parts of their locomotor repertoire’, DeSilva wrote in the journal Proceedings of the National Academy of Sciences. ‘If early hominins were engaging in any substantial amount of arboreal climbing, then they were doing it in a manner ... distinct from modern chimpanzees’.
The development of bipedalism had involved sacrificing climbing skills because the body proportion required for each was different. ‘I think by 3 to 4 million years ago that trade-off was occurring’, said DeSilva. ‘Our ancestors were becoming very capable upright walkers, and it came at the expense of our ability to climb trees’.
Amid all the speculation about the origins of bipedalism, about the only certainty seemed to be that hominid ancestors living in tropical forests managed to develop ways of holding themselves upright in trees, passing on the advantage to generations that began to spend more time on the ground.
CHAPTER 14
LITTLE FOOT
IN THE POST-APARTHEID era, South Africa joined in the run of discoveries, opening up new vistas not only on human ancestors but on modern humans. Throughout the apartheid era, while South Africa was shunned by the rest of the world, South African palaeoanthropologists and palaeontologists had persevered with their research, turning Sterkfontein and Swartkrans into the two richest cave sites in the world. By 1994, Sterkfontein alone had yielded more than 700 australopithecine specimens—males and females, infants, children, adolescents and adults—ranging in age from 3 million years to less than 1 million years. But it was a piece of brilliant detective work in the post-apartheid era that led to the most spectacular discovery of all.
In 1994, Ron Clarke, the field director at Sterkfontein, was searching through boxes of fossil animal bones collected previously from a deep underground cavern known as the Silberberg Grotto when he found several hominid foot bones among the jumble of remains that had been overlooked. The fossils had been chiselled out fourteen years before from breccia blocks originally blasted out from the lowest levels of the Silberberg Grotto by lime workers in the 1920s and 1930s.
Clarke was already renowned in the trade for his exceptional skills as a palaeontologist. Born in England in 1944, he had worked for six years as an assistant to Louis Leakey, displaying a particular talent for reconstructing hominid fossils. He had also helped Mary Leakey excavate the Laetoli footprints. He had been in charge of excavations at Sterkfontein since 1991.
Examining the bones, Clarke concluded that four of them belonged to the left foot of an Australopithecus. The bones revealed apelike as well as humanlike characteristics, indicating that the australopithecine had been both bipedal and prehensile, with a grasping tree-climbing capability, spending time in the trees as well as on the ground. Even on their own, the four conjoining bones represented a highly significant find; they were estimated to date back more than 3 million years, making them the oldest hominid discovery yet made in South Africa. In his initial report, Clarke speculated that the australopithecine had fallen down a narrow shaft into the underground cave system and died there, along with a variety of animals. Because the bones were so small, Phillip Tobias proposed naming the specimen ‘Little Foot’.
Three years later, in May 1997, Clarke happened to open a cupboard in the hominid strong room at the Witwatersrand Medical School and noticed a box labelled ‘Cercopithecoids’, containing monkey fossils taken from the Silberberg Grotto.