The "Science" of Paleoanthropology (Human Fossils) — Exposed!

In this article, an evolutionary paleoanthropologist describes the subjectivity and questionable science inherent in his own discipline!

All quotations are from Roger Lewin. 1997. Bones of Contention. 2nd edition. Chicago: University of Chicago Press. Page number references from this book are given at the beginning of each section. Bold print indicates emphasis added.

[page 5] Paleoanthropology, like all sciences, is an activity done by people and is therefore prey to the same kinds of subjective interpretations and personal interests that influence other activities done by people, such as politics. No scientist likes to be shown to be less than scientific, and yet virtually everyone I talked to helped me to do just that.

[pages 18-19] . . . scientists, contrary to the myth that they themselves publicly promulgate, are emotional human beings who carry a generous dose of subjectivity with them into the supposedly "objective search for The Truth."
     In fact, a completely unbiased, unprejudiced exploration of nature is a methodological impossibility, as biologist and philosopher of science Sir Peter Medawar is fond of pointing out. Without a set of expectations to act as a guide, such a search would be a chaotic and largely unprofitable enterprise. Moreover, the way in which scientists typically report their findings, in formal papers submitted to learned journals, is, he says, "notorious for misrepresenting the process of thought that led to whatever discoveries they describe." Preconceptions are rarely acknowledged, because this, after all, would be "unscientific." And yet preconceptions are an individual scientist's guide to how to view the world with a degree of order that allows structured questions to be asked. . . .
     [Donald] Johanson readily agrees that paleoanthropology is no different from other sciences in this respect. "The fossil finders themselves have often brought with them their own personal prejudices and beliefs . . . We see discoveries as bolstering our specific interpretation of what the family tree should look like." [Richard] Leakey's view is similar. "In our family we were working with the human sciences, and I was never shown examples of objectivity in the true sense of what science is supposed to be like."

[page 20] Paleoanthropology is thus no different from other sciences in being controversial. What sets it off from other sciences is the degree of controversy it engenders. Yes, controversy is found in all sciences, but in paleoanthropology discernibly more so. Yes, preconceived ideas shape the progress of all sciences, but nowhere else to the degree that occurs in the search for human origins. And yes, personalities are important in the flow of all sciences, but, again, in the science of man emphatically so. "All sciences are odd in some way," notes Duke University anthropologist Matt Cartmill, "but paleoanthropology is one of the oddest." [cf. p. 319]

[page 27] It is an unfortunate truth that fossils do not emerge from the ground with labels already attached to them. And it is bad enough that much of the labeling was done in the name of egoism and a naive lack of appreciation of variation between individuals: each nuance in shape was taken to indicate a difference in type rather than natural variation within a population. This problem has in some part been eased in [the last half-century]. But it remains inescapably true that applying the correct label is astonishingly difficult, not least because such labels are in a sense arbitrary abstractions; and especially so when the material on which the analysis is being done is fragmentary and eroded. "It is an incredibly difficult problem," says Lord Zuckerman. ''It is one so difficult that I think it would be legitimate to despair that one could ever tum it into a science."

[pages 42-43] During her reading of the paleoanthropological literature, [Misia] Landau was intrigued not only by these grand narratives and philosophical assumptions, but also by the way in which practitioners talked about the hard evidence: the fossils. And here one can focus much more closely on current writings. There is a strong tendency, she claims, for fossils to be presented as if they were lucid texts to be read unambiguously, rather than scrappy fragments of unknown morphologies to be interpreted. "Let the fossils speak for themselves" is a phrase that's frequently spoken or written. Moreover, even when fossils are being described in the most technical terms, authors often invest their words with unspoken arguments: there are texts beneath the texts, she suggests. "The question to ask, then, is not what do fossils tell us about human evolution but what is it about human evolution—and not only human evolution—that through fossils is getting said." . . .
     In fact, "virtually all our theories about human origins were relatively unconstrained by fossil data," observes David Pilbeam. "The theories are . . . fossil-free or in some cases even fossilproof." This shocking statement simply means that there is and always has been far more fleshing out of the course and cause of human evolution than can fully be justified by the scrappy skeleton provided by the fossils. As a result, he continues, "our theories have often said far more about the theorists than they have about what actually happened."

[pages 54-55] In his position as director of the American Museum, [Henry Fairfield] Osborn was the natural spokesman in favor of evolution against the likes of William Jennings Bryan, who was the chief prosecutor at the Scopes trial. This Osborn carried out with enormous exuberance, bringing his powerful personality to bear on every public medium he could exploit. He wrote articles for The New York Times and made frequent radio broadcasts, berating the fundamentalists' attacks on evolutionary theory. And he was delighted to be able to claim evidence for the existence of early human progenitors in the United States—namely, a tooth discovered by paleontologist Harold Cook early in 1922 in Bryan's own home state, Nebraska. Osborn, being an orator of some considerable force, if not the subtle talent of Bryan, was able to make great play of that association. Alluding to the quotation from the Book of Job (12:8) "Speak to the earth, and it shall teach thee," Osborn wrote in 1925: "The earth spoke to Bryan, and spoke from his own native state of Nebraska."
     Named by Osborn Hesperopithecus haroldcookii, or more popularly Nebraska Man, the tooth was considered to be that of a very early anthropoid which had inhabited the shadowy beginnings of humanity. For Osborn, a devout man, its discovery was an answer to his prayers in the cause of evolution. Eventually, however, the tooth was shown to be that of a peccary (a kind of pig), and not that of an anthropoid at all, which revelation proved to be more than a little embarrassing for the museum's director.

[pages 60-61] . . . the infamous Piltdown Man, the "fossil" that held the British anthropological establishment in its thrall for nigh on four decades. . . .
     In the face of varying degrees of skepticism from North America and continental Europe, the British anthropological establishment concluded in near unanimity that [the Piltdown] jaw and cranium were indeed from one individual, that it was an ancient form of humanity, and what is more, its unusual form was precisely what would have been predicted, given prevailing theory. Virtually every major voice in British anthropology proclaimed that although the cranium was clearly very modern in aspect, many apelike features could also be discerned; and that while the jaw certainly looked like that of an ape, the trained eye could readily discern important human characteristics in it.
     In fact, as was discovered a long forty years after its first announcement, the Piltdown Man was a hoax, a fraudulent seeding of the Piltdown gravel pits with fragments from a modern human cranium and an orangutan's jaw. Unsolved to this day, the Piltdown forgery remains one of the great whodunits of modern times.
     The puzzle of the culprit's-or culprits'-identity has of course fascinated amateur historical sleuths for years, with the result that virtually everyone involved in the discovery and study of Piltdown has at some time or other been fingered as the perpetrator. As a result, says Michael Hammond, a sociologist of science at the University of Toronto, the real story of it all has been somewhat obscured: "namely, what could have led so many eminent scientists to embrace such a forgery?" How is it that trained men, the greatest experts of their day, could look at a set of modern human bones—the cranial fragments—and "see" a clear simian signature in them; and "see" in an ape's jaw the unmistakable signs of humanity? The answers, inevitably, have to do with the scientists' expectations and their effects on the interpretation of data.

[page 64] . . . paleoanthropology, a science that is often short on data and long on opinion.

[pages 68-69] The scientific literature of [Marcellin] Boule's time is replete with expression of Edwardian revulsion and even moral indignation at the supposed brutishness of Neanderthals. lt would, however, be a mistake in Boule's case to conclude that his technical assessments were based on this perceived brutishness. In fact, it was rather the other way around. His preconceptions—primarily that human history was like a bush, not a ladder—demanded that Neanderthals be as different as possible from modern humans, and so he needed to exaggerate those differences which did exist and even invent some which didn't. The result was that Neanderthal looked more brutish than he really was. . . . most anthropologists [now, i.e. in 1997] agree that Neanderthal should be called Homo sapiens neanderthalensis—in other words a subspecies and a very close relative to our own.

[page 73] "The Piltdown skull, when properly reconstructed, is found to possess strongly simian peculiarities," noted [Sir Grafton] Elliot Smith. "In respect of these features it harmonizes completely with the jaw, the simian form of which has not only been admitted, but also exaggerated by most writers." In other words, Elliot Smith was able to see signs of humanity in the orang jaw and features of an ape in the human cranium. "That the jaw and cranial fragments . . . belonged to the same creature there has never been any doubt on the part of those who have seriously studied the matter," he opined somewhat peremptorily in 1914. . . .
     Being a neurologist, Elliot Smith also examined the form of the brain impressed on the inner surface of the cranium. "There are clear indications," he said, "that mere volume is not the only criterion of mental superiority. Those parts of the organ which develop latest in ourselves were singularly defective in [Piltdown]." There are clear echoes here of Boule's assessment of the Neanderthal's supposed inferior mental capabilities, simply because of an assumed primitiveness. Remember, Elliot Smith was in fact describing a fully modern human brain.

[page 75] "All the collateral lines of evidence appeared to be mutually confirmatory and in complete harmony with each other," commented [Sir Wilfred] Le Gros Clark when he discussed the [Piltdown] forgery at a lecture at Britain's Royal Institution not long after its exposure. "So much so, indeed, that . . . none of the experts concerned were led to examine their own evidence as critically as otherwise they would have done." A clearer message for the process of science can hardly be imagined.

[pages 85-86] "I will never again cling so firmly to one particular evolutionary scheme," announced David Pilbeam at the beginning of 1978. "I have come to believe that many statements we make about the hows and whys of human evolution say as much about us, the paleoanthropologists and the larger society in which we live, as about anything that 'really' happened."
     This dramatic public recantation shocked the paleoanthropological profession, because it represented more than a shift in just one person's philosophy of science. For a decade and a half Pilbeam, with his Yale colleague Elwyn Simons, had embodied the science's virtually unanimous commitment to one particular view of human origins. Namely, that humans split away from ape ancestors at least 15 million years ago; and that the first member of the line leading to us was a baboon-sized creature known as Ramapithecus. . . .
     The dethroning of Ramapithecus—from putative first human in 1961 to extinct relative of the orangutan in 1982—is one of the most fascinating, and bitter, sagas in the search for human origins. Some practitioners describe it as an exemplary illustration of how the science should proceed: that is by changing its hypotheses on the basis of each new item of evidence. Others, by contrast, charge that there are echoes of the Piltdown affair, in the sense of experts seeing in the fossils precisely what they want to see. There is no doubt, however, that in addition to the confection of egos and reputations that spices any academic fight, the controversy over Ramapithecus shows once again how the great difficulty of inferring relationships from fossil shapes can lead to serious intellectual battles.

[page 123] "Contrary to Simons' and my original view, Ramapithecus itself does not have a parabolic dental arcade," says Pilbeam. "I 'knew' Ramapithecus, being a hominid, would have a short face and a rounded jaw—so that's what I saw." Pilbeam and Simons were not uniquely guilty of this error. It occurs often, such is the uncertainty of interpreting fragmentary anatomy in fossils.

[pages 126-127] The clearest message of the Ramapithecus affair, however, is the power of preconceptions, which in this case led competent scientists to ignore the evidence of other competent scientists because the conclusions drawn from the evidence were at variance with established ideas. All scientists are guided to some degree by a set of assumptions, usually implicit rather than explicit. "I try hard to detect them in my own thinking," says Pilbeam, "to isolate those assumptions that are not articulated because they are so 'obvious,' yet will seem so silly a few years from now. I am also aware of the fact that, at least in my own subject of paleoanthropology, 'theory'-heavily influenced by implicit ideas-almost always dominates 'data.' . . . Ideas that are totally unrelated to actual fossils have dominated theory building, which in tum strongly influences the way fossils are interpreted."

[page 160] As might be imagined, there was a great deal of discussion around the Koobi Fora camp and back at the museum in Nairobi about what [the skull labeled KNM-ER] 1470 might be, for it was not unequivocally any known species. One point of uncertainty was the angle at which the face attached to the cranium. Alan Walker remembers an occasion when he, Michael Day, and Richard Leakey were studying the two sections of the skull. "You could hold the maxilla forward, and give it a long face, or you could tuck it in, making the face short," he recalls. "How you held it really depended on your preconceptions. It was very interesting watching what people did with it." Leakey remembers the incident too: "Yes. If you held it one way, it looked like one thing; if you held it another, it looked like something else. But there was never any doubt that it was different. The question was, was it sufficiently different from everything else to warrant being called something new?"

[page 162] When a new species is named, the author has to cite a so-called type specimen, against which other workers can compare similar fossil material. In addition, the author can add additional specimens, known as "paratypes" and "referred material," which allow further comparisons. With Homo habilis there are seven separate fossils cited in all. Now, according to many authorities, this array of fossils erroneously includes representatives of two species, not just one, as it is meant to. Some of these fossils are accepted as Homo while others may well be Australopithecus africanus. So, although as a collection these seven fossils are meant to define Homo habilis, instead they cast a veil of ambiguity over the species. This creates a problem for people who, when analyzing a new fossil, wish to know if it is Homo habilis or not. The answer is, well, it depends on what you mean by Homo habilis. The required comparison, formally speaking, cannot be unequivocal because of the mixed sample.

[page 271] No scientist likes to see his pet theory swept aside, and this is especially so in paleoanthropology, where individual researchers tend to be more intimately involved with and proprietary about their theories than in other sciences.

[pages 299-300] So, after analyzing the same set of fossils [including "Lucy" and others], three different research groups come to three different conclusions. "No position is overwhelmingly strong," observes David Pilbeam, "which probably means there simply isn't enough fossil material available to allow a fully objective assessment." [Cf. page 334: We are left with the position so often reached earlier in this book: two groups of anthropologists, faced with the same fossil evidence, come to diametrically opposed conclusions.]

[page 307] Racism, as we would characterize it today, was explicit in the writings of virtually all the major anthropologists of the first decades of this [twentieth] century, simply because it was the generally accepted world view. The language of the epic tale so often employed by Arthur Keith, Grafton Elliot Smith, Henry Fairfield Osborn, and their contemporaries fitted perfectly an imperialistic view of the world, in which Caucasians were the most revered product of a grand evolutionary march to nobility. . . .
     Roy Chapman Andrews, Osborn's close colleague at the American Museum, stated the issue bluntly. "The progress of the different races was unequal," he said. "Some developed into masters of the world at an incredible speed. But the Tasmanians, who became extinct about 1870, and the existing Australian aborigines lagged far behind . . . not much advanced beyond the stages of Neanderthal man."

[pages 312-318] In the physical realm, any theory of human evolution must explain how it was that an apelike ancestor, equipped with powerful jaws and long, daggerlike canine teeth and able to run at speed on four limbs, became transformed into a slow, bipedal animal whose natural means of defense were at best puny. Add to this the powers of intellect, speech, and morality, upon which we "stand raised as upon a mountain top," as [Thomas Henry] Huxley put it, and one has the complete challenge to evolutionary theory.
     Darwin's answer to this was to look at those faculties which appear to make us special—our brains, our bipedality, our use of tools, our sociality—and suggest that, developed little by little, they would give us a competitive edge in the world of brute nature. It was an explanation that made our earliest ancestors already human, albeit to a rudimentary degree. . . .
     Darwin's ideas on human origins—in which our "special" attributes were self-explanatory through the incremental advantage of natural selection—persisted into the twentieth century, through the era of Arthur Keith and Henry Fairfield Osborn and on into the 1950s. . . .
     When, during the 1930s and '40s, the discoveries of australopithecine fossils in South Africa showed that human forebears stood upright and were equipped with small brains as well as small canine teeth, the Darwinian structure began to come apart. Intelligence could not have been an important engine in human evolution if most of the major physical changes in the skeleton had occurred with virtually no expansion in apparent mental capacity. A new explanation was required, and was soon provided. Tool use now emerged as the focus of human advancement, especially tools used as weapons: the era of the killer ape dawned, which was a vastly less flattering self-image than the one of nobility and spirituality enjoyed by Darwin, Keith and their contemporaries. . . .
     So, bipedality, intelligence, tool use, culture, and society—all those features which make us human and which had been accounted for by Darwin as the outcome of incremental benefits favored by natural selection—now had a different explanation: hunting. . . .
     From the mid 1970s on, the hunting hypothesis and all that it implied began to fall apart, for a number of different reasons. First of all, with new and spectacular discoveries made in East Africa, it began to be clear that the first stone tools in the archeological record do not begin to appear until at least a million years after the earliest hominids had already evolved a fully bipedal gait. In the absence of stone tools as weapons and butchery implements at the beginning of the human line, the argument for hunting as the driving force behind the origin of bipedalism simply vanished. As a result of a subsequent reexamination of the archeological evidence, paleoanthropologists now suspect that fully developed hunting of the sort that so fired the collective imagination a decade ago was adopted only very recently in human history. It may be that our forebears were opportunistic scavengers, not hunters, for most of their career—an idea that many find most unflattering to our self-image. . . .
     From the mid 1970s onward, the hunting hypothesis was also attacked from theoretical standpoints. One, developed by the late Glynn Isaac and promulgated by Richard Leakey in several popular books, emphasized sharing and cooperation as the key behavioral ingredients in hominid origins and human success. Owen Lovejoy, meanwhile, suggested that demographic and nutritional demands spurred the development of bipedalism and monogamous bonding between males and females. As a counterpoint to the male-oriented hunting hypothesis, Adrienne Zihlman and Nancy Tanner suggested that the mother/infant bond and food-sharing among mature females were at the core of hominid origins.
     Whatever the relative merits of these various proposals—and it is not easy to test all of them in the record—each has the clear intention of replacing a distinctly aggressive image of human origins with a distinctly peaceable one. "But why are people trying so hard to do that?" asks Matt Cartmill. "The striking thing about these theories is that they go so far beyond the available evidence in an effort to show that hunting was not important in early hominid evolution—just as the killer ape theorists did to prove that it was crucial." Why? What lies behind it? "When people turn indignantly from one sort of speculation to embrace another, there are usually good, nonscientific reasons for it," Cartmill observes.
     These reasons might include an attempt to turn away from the pessimistic view that humans are bound by their very nature to annihilate themselves through the agency of nuclear war. Or to reject the idea that through our heritage, we are innately programmed to behave in any particular manner at all, and especially in an undesirable manner. But in the long run it is of little account what these reasons are, because they are the reasons of the moment. They are, as John Durant says, "a direct response to contemporary social experience." These peaceable theories of human origins, like the beast-in-man idea, become "a mirror which reflected back only those aspects of human experience which its authors wanted to see. . . . This is precisely what we would expect of a scientific myth."

[page 319] Paleoanthropology has, always has had, as its major goal the search for man's place in nature. The science shares with all historical sciences the limitations of trying to reconstruct events that occurred just once: there are no experiments to be done that can confirm or deny the major themes that are sought. It also shares with all sciences the truism that science is an activity done by people, and is therefore subject to the unavoidably personal and erratic nature of intellectual progress. But paleoanthropology alone among all the sciences operates within [an additional] dimension, with humanity's self-image invisibly but constantly influencing the profession's ethos.
     As Matt Cartmill said, "All sciences are odd in some way, but paleoanthropology is one of the oddest." For this reason, there will always be bones of contention.

For further reading:

Andrew Lansdown, "Differences between humans and animals" [pointed humour]. Creation, Vol. 17 No. 4 (Sep 1995), p. 45. <>