what remains copy/1988 what remains.pdf · would not be interested. leakey, johanson and other ......

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WHAT REMAINS

Harriet Ritvo

paleoanthropology is very now-high tech, mass media, supercharged. This is the unmistakable message of

Roger Lewin's opening passage in Bones of Contention: Controversies in the Search for Human Origins (Simon and Schuster). Richard Leakey and Donald Johanson, two of the most visible and charismatic combatants in recent debates about the fossil remains of our ancestors, confront each other not in a seminar room or a laboratory or even at a dusty excavation site in eastem Africa, but in an improvised television studio presided over by Walter Cronkite at the American Museum of Natural History in New York. Their subject must be hot,-otherwise Cronkite would not be interested. Leakey, Johanson and other paleontological highfliers operate at a jet-age pace and on a jet-age scale. More like corporate executives than run of-the-mill professors and scientists, they move constantly from continent to continent, giving lectures, raising money and crossing swords. Nor are they up-to-the-minute only in professional style. In recent decades the time-honored

method of describing and interpreting fossil remains, es sentially a petrified version of comparative anatomy, has been supplemented by techniques derived from such in novative fields as geophysics and (most spectacularly)

molecular biology. But paleoanthropology is also very then. To some ex

tent, this is inevitable. Both its subject (human ancestors) and its primary material (their fossilized remains) are extremely old. (How old is open to question and lies be hind many of the controversies that Lewin chronicles. But in any case, multiple millions of years.) Except when dramatically presented in the pages of popular magazines or in a blockbuster museum exhibition like the "Ancestors" show assembled by the American Museum of Natural His tory in 1984, these fragmented and worn bits of petrified skeleton often look archaic in a double sense. As they illustrate their own great age, they also underline the

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HARRIET RITVO

traditional attributes of the discipline that studies them. Locked away in drawers or crowded into the overcata logued but underexplained museum cabinets of past gen erations, they implicitly define paleoanthropology as an old-fashioned, perhaps even a Victorian, pursuit.

In this case-although, as Lewin repeatedly points out, not in every case-the fossils speak authoritatively. The study of human and hominid fossil remains emerged as an organized discipline in the nineteenth century, along with the allied fields of paleontology and anthropology. (Hu

man remains include those of all species belonging to the genus Homo, of which we are the only current representa tive; we are also the only current representative of the family Hominidae, which includes, in addition to Homo, at least one extinct genus, Australopithecus. The bound aries and, to some extent, the definitions of all these cate gories are controversial.) Despite recent methodological advances, the scientific objectives of paleoanthropologists remain similar to those of the founders of their discipline. They still search for significant fossils, then meticulously describe them and finally identify their appropriate taxo nomic niche-that is, either assign them to a previously described species or construct al entirely new species to accommodate them.

The work of paleoanthropologists is not shaped solely by technical concerns, however. Paleoanthropology also engages broad questions, and these connect it with yet older intellectual traditions. Philosophers and theologians debated the role of humanity in the scheme of things long before the problem was appropriated by scientists in the last century. Lewin implicitly reiterates this chronology by entitling the concluding chapter, in which he addresses some of these grander issues, "Man's Place in Nature,"

which is borrowed from the great Victorian scientist Thomas Henry Huxley. Perhaps paradoxically, it is the very persistence of unscientific concems that gives paleo anthropology its current magnetism; indeed, although they do not always admit it, professional paleoanthropologists share such concerns with their nonspecialist public. Lewin is himself a scientist (he trained as a biochemist before embarking on a distinguished career as a scientific journal

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ist), but his own reactions to the fossil presence of distant human precursors reveal a depth of mystical feeling that their technical sigficance cannot entirely explain. Of one of the exhibits in "Ancestors," he says, "There is something inexpressibly moving about cradling in one's hands a cra nium drawn from one's own ancestry"; holding one of the first australopithecine skulls to be discovered moves him to exclaim, "Cradle the little fossil in the palm of your hand, look into its now-blank eye sockets, and you get a feeling of staring way back into your own past." The bones are not intrinsically impressive or evocative enough to in spire such rhapsodies. One of the photographs reproduced in Bones of Contention shows a long tableful of Donald Johanson's revolutionary Ethiopian finds, including the "first family" and the celebrated Lucy. Only Lucy has a recognizably humanlike form, or indeed any recognizable forn, and even she is quite fragmentary; the rest are sim ply broken pieces. Visually, the most compelling (if least germane) element of the picture is the army of about a hundred modem chimpanzee skulls ranged behind the fos sils. But Lewin's language signals the true source of all this fascination-a sense of communion with his own begin nings that almost transcends the natural.

Usually, however, Lewin's explications of recent con flicts among paleoanthropologists avoid the heights of ideology and theology, which is not to say that he presents such struggles as resulting simply, as conventional scien tific piety would have it, from the energetic yet dispas sionate pursuit of truth. Instead, in the vein of much recent

work by humanists and social scientists who study science as a cultural phenomenon, he stresses the role of personal ambitions and interpersonal relations, of institutional and disciplinary politics in determining who ends up on which side of any scientific debate, and what they say and do about it. He repeatedly challenges the widely held as sumption that scientific methods and the interpretation of scientific evidence can be shielded from the influence of researchers' preconceptions and biases, whether these are technically, politically or personally inspired. As a result his lucid and detailed discussions of the issues that have divided the last two generations of paleoanthropologists

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are spiced with trenchant and engaging insiders' insights into personalities, methods and motives. Sometimes these come from the horse's mouth, and sometimes Lewin re casts or distills them. In any case it is a testimonial to his judiciousness that he seems to give equal time and sym pathy to all parties, even though he has collaborated on two books with Richard Leakey, one of the major bellig erents; it may also be a testimonial to his personal quali ties that many of the notables who figure in his narrative

were willing to contribute appreciative squibs for the back of the jacket.

This emphasis on sociological and political explanations sometimes leads Lewin to slight the deeper ideologies that also help determine (or overdetermine) the profes sional behavior of scientists. He is inclined, for example, to overlook the fact that the subject matter of paleoan thropology overlaps significantly with that of Genesis.

Thus he attributes the recurrent desire of scientists to locate distinctively hominid ancestors (as opposed to those we share with chimpanzees, gorillas and other apes) in the remotest possible past to the personal desire for glory (superlatives like "oldest" tend to grab headlines in professional journals as well as in popular magazines) or the disciplinary desire to claim the largest possible chrono logical territory, rather than to a persistent, if unacknowl edged and indeed unconscious reluctance to accept the

message of kinship embodied a century ago in Darwin's Descent of Man. Similarly, Lewin chalks up the easily aroused public interest in old hominid bones simply to the narcissism characteristic of Homo sapiens.

Although Lewin's interpretations of the positions taken by scientists can be reductive along this single dimension, this is primarily a matter of emphasis, not of omission. As Lewin is both full and fair in recounting the gossip sur rounding paleoanthropological debates, so his explana tion of the substance of those debates is as generously and clearly detailed as the limits of his nontechnical format allow. Bones of Contention is structured around a series of arguments that have engaged students of human origins for the last half century or so. It begins in the 1920s, with the furor provoked by Raymond Darts claim, now recog

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nized as both justified and extremely sigficant, that the fossil he called "the Taung child" should be classified as a hominiid, although in a new genus, Australopithecus, not in Homo. Nothing so primitive had been placed among our close relatives before, and most of Dart's colleagues dismissed his find, often with either condescension or out rage, as an extinct ape species. The book concludes where it begins, with Lucy and the ongoing debate about the taxonomical and genealogical significance of the unpre cedented wealth of hominid fossils uncovered in eastern Africa during the past two decades. How many species these bones represent, which are Australopithecus and

which are Homo, what relation they bear to each other and to modern Homo sapiens, and therefore when and in

what form the line leading to us separated from other hominids, are all still at issue. Th-ese controversies and the others that Lewin describes carry high stakes on every level-personal, institutional and ideological. Although Lewin usually chooses to explicate them in terms of per sonal and institutional motivations, his full discussion also provides strong evidence of the influence of ideology.

Thus it is easy to connect the widespread desire of field paleoanthropologists to discover the oldest possible human ancestor with an equally widespread but superficially con tradictory reluctance to include in the human lineage any form that seems too closely related to modern apes. In deed, internal contradiction is an intrinsic feature of this paleoanthropological position, since none of its adherents rejects evolution, and therefore all must recognize that, at some point in the past, there existed a species that gave rise to all modern hominoids (hominoidea is the taxo nomical category-a superfamily-that includes humans and apes). But from this point of view, shared ancestors look more acceptable as they recede into the mists of time. Thus Henry Fairfield Osborn, the president (1908 33) of the American Museum of Natural History and a vocal opponent of the notion that anything like Dart's "ape-man" could be a close human ancestor, projected instead a genealogy based on a series of "dawn-men," none of which seemed to diverge much from the modern human

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form, no matter how remote and ancestral they were al leged to be.

This fastidious formulation was recognized as implausi ble even at the time when professional consensus rejected Dart's claims. William King Gregory, a colleague of Os born's at the American Museum, characterized his position as "'pithecophobia," or fear of apes. Nevertheless, the un easiness about apelike relatives that underlay the rejection of the Taung child in the 1920s and 1930s survived the en shrinement of australopithecines in the hominid pantheon. In the 1960s it led paleoanthropologists to accept too easily the claim that a fossil species called Ramapithecus pun jabicus, which ultimately turned out to be an early orang utan, not directly related to modem humans, chimpanzees and gorillas, was in fact a hominid. What made this claim attractive, despite Ramapithecus's primitiveness in some respects-the creature was very small, for one thing, about the size of a baboon-was the age of the fossil, estimated at about 15 million years. As Lewin points out, if it were assumed that Ramapithecus was not the first hominid, this chronology allowed scientists to place the division between pongids (the family that includes modem apes) and hominids as far back as 30 million years. The rapidity

with which this dating made its way into anthropology textbooks is an indication of its potent appeal.

One reason that what turns out to have been an egre gious misclassification of Ramapit hecus was so widely and easily accepted is that it was based on very little--several jaw pieces. Making large inferences on the basis of small or fragmentary evidence is neither unusual nor irrespon sible paleontological procedure. Indeed, it is mandatory. Living forms are not predictably fossilized, and only some fossils are accessible even to the most skilled and intrepid hunters. Except in very unusual circumstances, inferences about the history of life are bound to be based on incom plete evidence. Awareness of this limitation usually makes paleontologists, including paleoanthropologists, very cau tious-but it also gives their imagination some scope. They can often hypothesize without fear of contradiction by counterevidence. Thus, although this paucity of pri

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mary material should make scientists eager for any un examined scrap, it sometimes has the opposite effect, lead ing, as Dart found to his dismay, to the rejection of new data that challenge cherished theories.

Ramapithecus was removed from the homimid family by evidence far removed from the traditional anatomical analysis of paleoanthropology. Working with genetic ma terial taken from modem hominoids, molecular biologists discovered that humans, chimpanzees and gorillas had shared a common ancestor no more than nine million years ago, and probably more recently. Thus a distinct hominid lineage had not arisen at the time that Rama pithecus flourished, and so no creature living then could be a part of it. At first most paleoanthropologists joined in rejecting this new source of data, defending their turf as

well as theeir ideological predilections. But, as in the case of the Taung child, ultimately orthodoxy changed. At pres ent, arguments about the ancientness of the hominid lin eage, such as that between Johanson and Leakey, with Leakey representing what Lewin identifies as the tra ditional British yen for the oldest possible date, take place within the limits of the new time scale proposed by molecular biology. (On the other hand, some cows are still too sacred to examine. As a result, the taxonomical impli cations of some related findings-that humans, climpan zees and gorillas are closer to each other than to orang utans, and that the human and the chimpanzee are slightly closer to each other than either is to the gorilla-have been largely disregarded. Taken together, these findings should seriously undermine the currently accepted distinction be tween the hominid and pongid families. Or, to put it an other way, they suggest that humans and apes should share a taxonomical category lower than superfamily.)

rThe lingering reluctance to acknowledge the close re lationship between humans and apes, whether in

their extant forms or their extinct ones, is not the only cur rent paleoanthropological habit of mind rooted in a re ligious natural history that has long since lost any explicit authority. The interpretation of fossil remains-or, more frequently, the refusal to accept otherwise plausible inter

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pretations-has repeatedly reflected the similarly based notion that at any given time there has been only one ex tant hominid species. W7e find ourselves in such a solitary position today, but this uniqueness is uncharacteristic of the animal groups to which humans are most closely re lated, whether these are defined as hominoids, primates or

mammals; on the contrary, within any taxonomic unit, evolution tends to take the forn of a bush with many branches. And, if it is examined by scientists unburdened by the "rule" of the lone hominid, the fossil record does suggest that many of our forebears had to share the earth, and even the same locality, with other hominids, members of evolutionary lineages that subsequently became extinct. Both Louis Leakey (the father of Richard) and Donald Johanson have made such claims, based on the rich re sults of their excavations in eastern Africa; both have en countered dogmatic criticism as a result.

Paleoanthropologists' persistent preference for figuring human evolution as a ladder rather than a bush bears a suggestive relationship to the scientifically outmoded but still widely shared conviction that human beings repre sent the highest possibilities of nature and the goal toward

which evolution is directed. Religion has not been the only source of unacknowl

edged ideological influence on paleoanthropology. Indeed, Lewin shows that almost any conviction or allegiance can shape interpretations in this highly charged field. Scien tists as well as the general public tend to see their fossil ancestors as reflections of themselves. It is likely that the Piltdown Man fraud (mock fossils composed of the cra nium of a modern human and the jaw of a modern orang utan) perpetrated in the 1910s was successful precisely because British scientists were so pleased to find a human ancestor on their own doorstep. And they stayed loyal to Piltdown Man until he was definitively discredited in 1953, although North American and Continental European an thropologists had doubted from the beginning. But the

British anthropological establishment could be skeptical when it chose, and its Continental counterparts could be credulous. German scientists around the turn of the cen tury were inclined to view the Neanderthal remains that

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had been uncovered in their country as ancestral to hu mans, while their English colleagues were glad to see them pushed aside, making room, as it turned out, for Piltdown Man. When larger geographical questions were at issue, however, Europeans and Americans tended to see things in the same light. Many of what now appear as the major false steps of twentieth-century paleoanthro pology were at least in part the result of a strong and widespread desire not to locate the birthplace of humanity in Africa. Lewin suggests that one reason that Dart's col leagues so persistently rejected his categorization of the

Taung child as a hominid was that such a categorization definitively placed the earliest human ancestors in south ern Africa. Conversely, among the attractions of Rama pithecus as an early hominid was its Indian provenance.

This implicit racism had been a feature of paleoanthro pology from the beginning. Nineteenth-century diagrams of human evolution often traced our development from apelike creatures, through something like cave men, and then through what were considered as lower modern forms, most often including the indigenous peoples of

Australia and Africa. The ladder was crowned by the in habitants of either ancient Greece or modern northwestern Europe, depending on the predilections of the schema tizer. The commitment to a non-African genesis of hu

mankind was an attenuated version of this, and related assumptions doubtless continue to shape contemporary paleoanthropology, despite the fact that the ideology latent in the science of our own time is more difficult to recognize than is that latent in the work of our predeces sors. Among the many strengths of Bones of Contention is that it encourages us to see how, in a variety of ways, science is shaped by the context in which it is done. Al though, as Lewin makes clear in an early chapter, even the "hardest" sciences are so conditioned, paleoanthro pology is a field particularly well suited for such an analy sis. It offers absorbing technical controversies (which can be explained for nonspecialists without sacrificing too much significant complexity), colorful and loquacious characters and theories that have occasionally been in cendiary far outside the arena of scientific debate. Best of

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all, it deals with a subject matter over which scientific dominion is still contested to an extent unusual in the late twentieth century, and about which almost everyone has strong feelings. And although the stock of reliable knowl edge continues to increase, no definitive description of the human evolutionary tree is yet in sight. This is due only in part to such technical problems as the gaps in the fossil record. It may also be implicit in the discipline of paleo anthropology itself. As we continue to reshape the present,

we will inevitably continue to reshape the past.

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what remains copy/1988 what remains.pdf · would not be interested. leakey, johanson and other ......

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