COMMENT SUSTAINABILITY Citizens and POLICY End the bureaucracy THEATRE Shakespeare’s ENVIRONMENT James Lovelock businesses must track that is holding back science world was steeped in on surprisingly optimistic governments’ progress p.33 in India p.36 practical discovery p.39 form p.41 The foot of the apeman that palaeo­ ‘handy man’, anthropologists had been Homo habilis. recovering in southern Africa since the 1920s. This, the thinking went, was replaced by the taller, larger-brained Homo erectus from Asia, which spread to Europe and evolved into Nean­ derthals, which evolved into Homo sapiens. But what lay between the australopiths and H. erectus, the first known human? BETTING ON AFRICA Until the 1960s, H. erectus had been found only in Asia. But when primitive stone-chop­ LIBRARY PICTURE EVANS MUSEUM/MARY HISTORY NATURAL ping tools were uncovered at Olduvai Gorge in Tanzania, Leakey became convinced that this is where he would find the earliest stone- tool makers, who he assumed would belong to our genus. Maybe, like the australopiths, our human ancestors also originated in Africa. In 1931, Leakey began intensive prospect­ ing and excavation at Olduvai Gorge, 33 years before he announced the new human species. Now tourists travel to Olduvai on paved roads in air-conditioned buses; in the 1930s in the rainy season, the journey from Nairobi could take weeks. The ravines at Olduvai offered unparalleled access to ancient strata, but field­ work was no picnic in the park. Water was often scarce. Leakey and his team had to learn to share Olduvai with all of the wild animals that lived there, lions included. They found the first trace of the poten­ Fifty years after tial toolmaker, two hominin teeth, in 1955. But these were milk teeth, which are not as easy to link to taxa as permanent teeth. The team’s persistence was rewarded in 1959, Homo habilis when archaeologist Mary Leakey, Louis’s wife, recovered the cranium of a young adult. Bernard Wood explains why the announcement of The specimen still boggles the mind because it is so strange: its small brain, large face, ‘handy man’ in April 1964 threw the field of hominin tiny canines and massive, thumbnail-sized evolution into a turmoil that continues to this day. chewing teeth were not at all like those of H. erectus. Its big molars earned it the nick­ name ‘Nutcracker Man’. alf a century ago, the British–Kenyan to this day. Even with all the fossil evidence Because Nutcracker Man was found in the palaeoanthropologist Louis Leakey and analytical techniques from the past same layers as the stone tools, the Leakeys and his colleagues made a contro­ 50 years, a convincing hypothesis for the assumed that it was the toolmaker, despite its Hversial proposal: a collection of fossils from origin of Homo remains elusive. odd appearance. But when Louis announced the Great Rift Valley in Tanzania belonged In 1960, the twig of the tree of life that the discovery, he was not tempted to expand to a new species within our own genus1. The contains hominins — modern humans, the definition of Homo. That would have announcement of Homo habilis was a turn­ their ancestors, and other forms more closely eliminated any meaningful distinction ing point in palaeoanthropology. It shifted related to humans than to chimpanzees and between humans and australopiths. Instead the search for the first humans from Asia to bonobos — looked remarkably straight­ he erected a new genus and species, Zinjan- Africa and began a controversy that endures forward. At its base was Australopithecus, thropus boisei (now called Paranthropus 3 APRIL 2014 | VOL 508 | NATURE | 31 © 2014 Macmillan Publishers Limited. All rights reserved COMMENT : Homo sapiens Some would lump all early Homo heidelbergensis P. BOISEI WHO WAS RELATED Homo species into Homo Homo antecessor Denisovans erectus; others would split some TO WHOM? Homo oresiensis Fifty years ago, the introduction of into a new non-Homo genus. Homo habilis shook up views of our Homo neanderthalensis genus, and the classication of Homo ergaster/erectus early Homo is still debated. Paranthropus boisei Homo rudolfensis Homo habilis Australopithecus africanus Australopithecus sediba Australopithecus garhi Australopithecus afarensis LIBRARY TRUEBA/MSF/SCIENCE PHOTO : JAVIER 4 million years ago (approx.) 3 2 1 Present Australopithecus Homo habilis Paranthropus Later Homo Australopiths Remains of a boisei Normal-sized : HUMAN ORIGINS PROGRAM/SMITHSONIAN INSTITUTION; : HUMAN ORIGINS PROGRAM/SMITHSONIAN INSTITUTION; walked upright, foot and Nutcracker Man, later Homo H. NEANDERTHALENSIS but were also jawbone were with its distinctively species had adapted for judged too large jaws, is neither larger brains, climbing. human-like for Australopithecus nor longer legs and H. HABILIS an australopith. Homo. smaller jaws. Fossil discovered 1974. Fossil discovered 1964. Fossil discovered 1959. Fossil discovered 1909. boisei), to accommodate it (see ‘Who was (around 600 cubic centimetres) of H. habilis. so easily shoe-horned into a single species as related to whom?’). The proposal was met with considerable those from Olduvai3. I concluded that there In 1960, Jonathan Leakey, Louis and scepticism. Some thought that the fossils were were two distinct types of face within early Mary’s eldest son, found the lower jaw and too similar to Australopithecus africanus to Homo4, and so in 1992, I suggested that a sec­ BLACKBIRD/ALAMY; : SABENA JANE the top of the head of a juvenile hominin. justify a new species. John Robinson, a lead­ ond early Homo species, Homo rudolfensis, Dubbed Johnny’s Child, it very definitely did ing authority on australopiths, suggested that should be recognized5. Two decades later, a not belong to the same species as ‘Zinj’, and H. habilis was a mix of earlier A. africanus team led by palaeontologist Meave Leakey LIBRARY; MUSEUM/SCIENCE PHOTO HISTORY NATURAL 6 the Leakeys began to suspect that it was the and later H. erectus bones. Other research­ (Richard’s wife) confirmed the ‘two-taxon’ AUSTRALOPITHECUS real toolmaker. ers agreed that the species was new. Very few hypothesis I had proposed, using a face and Phillip Tobias, a palaeoanthropologist accepted that it was the earliest human. two lower jaws found at Koobi Fora. But known for his work in South Africa, had Subsequent finds shaped the debate. A they — correctly, I believe — refuted my sug­ already been recruited to analyse Zinj, so the crushed cranium (dubbed Twiggy) from gestion about which jaws went with which Leakeys turned to him to analyse the juvenile the lowest strata at Olduvai nixed Robin­ faces. As ever in palaeontology, new fossils cranium. John Napier, a specialist in hand son’s argument that H. habilis was a mix of test and refine old ideas. anatomy (as well as sleight-of-hand magic an australopith and H. erectus. Another skel­ tricks) was recruited to examine wrist and eton indicated that H. habilis had a stronger DRAWING THE LINE hand bones found with the skull. and relatively longer (or more ape-like) upper In 1999, British anthropologist Mark Collard An adult foot was excavated along with limb than did H. erectus and its ilk. and I looked7 afresh at the boundary between Johnny’s Child, and three years later, a cra­ A handful of additional specimens from Homo and more-primitive hominins by nium with both the upper and lower jaw was Ethiopia to South Africa have since been focusing on features that hint at body size, uncovered, as was a very fragmented cranium added to H. habilis; the biggest contribution posture, locomotion, diet and life history. with well-preserved teeth. Napier had already to early Homo has come from Koobi Fora in For example, how long is the upper limb convinced himself that the juvenile hand Kenya. I have been involved with H. habilis compared with the lower, or the forearm com­ bones were like those of modern humans. My for all but two of its 50 years, starting in 1966, pared with the upper arm? Do molar teeth PhD supervisor, Michael Day at the Univer­ when I analysed the ankle bone excavated erupt early, as in apes, or form slowly and sity of London had come to the same conclu­ alongside Johnny’s Child. Far from being like dawdle in the jaw, as in modern humans? All sion about the foot. And Tobias was certain that of modern humans, the bone is a much are attributes that help to reveal how an ani­ that neither the long crowns of the chewing better match for an australopith. Other fea­ mal makes its living and allocates its energy. teeth in the lower jaw nor the large brain case tures of H. habilis have also turned out to be Although H. habilis is generally larger than could belong to the australopiths known from less like those of modern humans than Louis A. africanus, its teeth and jaws have the same southern Africa. and his team suggested. proportions. What little evidence there is In the mid-1970s, Louis and Mary’s sec­ about its body shape, hands and feet suggest HANDY HYPOTHESES ond son, Richard, offered me the challenge of that H. habilis would be a much better climber Thus, in a paper published in Nature in making sense of the early Homo skulls, crania than undisputed human ancestors. So, if April 1964 (ref. 1), Louis, Tobias and Napier and jaws from Koobi Fora. It was a lonely task H. habilis is added to Homo, the genus has made the case for adding the ‘handy man’ to involving 15 years poring over australopiths an incoherent mishmash of features. Others the genus Homo as H. habilis. They argued and H. erectus fossils in museums around disagree, but I think you have to cherry-pick that the Olduvai fossils met three key crite­ the world.