Publications That (Should have) Made a Difference: No. 3. 'Thinking Out of The Box'

By Bernard Wood
October 03, 2013

If you go to a meeting of the American Association of Physical Anthropologists (AAPA) and make your way to the bar around 6pm an elderly but sprightly gentleman in a full white beard will be dining on the bar menu, probably with his wife Eleanor. Charles Oxnard, even in what is meant to be his retirement, seldom misses an AAPA meeting and he still publishes, but in the 1970s he was at the height of his considerable powers and influence and the article I feature in this blog (Oxnard, 1975a) dates from this period.

Charles Oxnard is the antithesis of a cookie-cutter scientist. He is a protégée of Solly Zuckerman and his main research interest was the application of multivariate methods to the analysis of the postcranial skeleton. He is a functional morphologist who approached the task of functional analysis using a combination of the comparative method and morphometrics. Although Zuckerman burned his fingers using multivariate analysis (see Director’s blog 24. Fruits of browsing: No. 4. ‘A feisty spat’) the researchers he inspired (e.g., Eric Ashton, Roger Flinn, Felix Lisowski, Charles Oxnard and Tom Spence) persevered with multivariate methods in a series of papers, many of which were published in the Journal of Anatomy. But Charles is unusual in that many of his ideas and results were published not in journals, but in a remarkable series of books, both small (Oxnard, 1973, 1975b) and large (Oxnard, 1983, 1987). The larger format books feature beautiful and thoughtfully drafted figures illustrating the complex relationships within and among the bones of the upper and lower limbs and the limb girdles of primates. Charles combines a facility with quantitative methods with an unusually acute visual sense. No one in our field is better at using images to communicate complex ideas and very few are better wordsmiths.

Most of Charles Oxnard’s research concerns living primates, but he has made the occasional foray into the analysis of the hominin fossil record and his lengthy review in Nature in 1975 deserves more attention than it has received from researchers. My prediction is that it will loom much larger in the history of paleoanthropology than its citation history suggests. Its message has particular resonance these days for, even though it does not use the word homoplasy, it has much to say about that topic. It is also one of the first papers, if not the first, to say explicitly that “bipedality may have arisen more than once” (ibid, p. 389) and one of the first papers to suggest that climbing may have been part of the locomotor repertoire of archaic hominins.

The 1975 review is in two parts. The longer first part presents some of the results of his research program that mostly, but not exclusively, focus on living taxa. The shorter second part plunges into the murkier world of paleoanthropology. Charles’ message in the first part is “it is thus information about function rather than genetic propinquity that is presumably best represented by such quantitative studies of skeletal fragments” (ibid, p. 390). Although he saw the postcranial skeleton as a mosaic, each component of which conveyed its own functional message “the total behaviour and the overall morphology of each living form is unique unto itself” (ibid, p. 391). Oxnard is one of the first researchers to appreciate the efficacy of thinking about how a living animal would look if all you knew about it was fragmentary fossil evidence.

Moving on to what was then called the ‘australopithecine’ fossil evidence, which in those pre-Lucy days did not amount to very much, Oxnard suggests that “in the multivariate investigations reported here [N.B., they mainly concern the talus] the various australopith fossils [N.B., CO and the Zuckerman school were skeptics about Homo habilis] are usually quite different from both man and the African apes (except in those features which are common to all hominoids or to all anthropoids).”… “The fossils … are a mosaic of features unique to themselves and features bearing some resemblances to those of the orang-utan” (ibid, p. 393).

Impressed by these results, I was caught between a ‘rock’ and a ‘hard place’. The ‘rock’ was that I was a graduate student of Michael Day, who was in the vanguard of advocating that one of Oxnard’s ‘australopithecines’ (aka H. habilis) was a biped practicing a type of bipedalism that could not be distinguished from the bipedalism practiced by modern humans. The ‘hard place’ consisted of Oxnard’s compelling results and the results of my own quantitative analyses.

But the really radical aspect of the review comes in the final two pages. In them he states something that does not seem so radical now, but which in 1975 was heretical, namely that “the australopithecines must have lain on an evolutionary side branch for a long time.” (ibid, p. 394). But the really radical proposal was that “perhaps as long as five million years ago or even longer there may have been creatures living that were generally somewhat similar to Homo erectus and therefore classifiable as man in a way that we must now deny to Australopithecus (whether named “H. habilis”, “H. africanus” or whatever else” (ibid, p. 394). So what encouraged him to adopt this radical idea?

Oxnard based it on three lines of fossil evidence:

First, Oxnard claimed, correctly, that a hominin talus [he was referring to KNM-ER 1813] from East Rudolf “dated at between 1.5 and 2.6 Myr” was “much more like that of man” than “the australopithecine talus from Olduvai” (ibid, p. 394).

Second, he cited the existence of “a skull [the ‘skull’ he referred to was the KNM-ER 1470 cranium] dated at almost 3 Myr” that had an endocranial volume that compared with Homo erectus. He claimed its morphology also “contrasted with australopithecines” (ibid, p. 394).

The third line of fossil evidence was “a fragment of arm bone perhaps four or more million years old from Kanapoi” that had been shown to be “very similar to that of modern man” (ibid, p. 394).

But it was Charles Oxnard’s bad luck that the dating evidence he was relying on for the antiquity of the two Koobi Fora fossils he refers to was flawed. It was even worse luck that in the very next paper in the same issue of Nature Garniss Curtis and his colleagues produced evidence that the KBS Tuff was not 2.6 Ma but just over 1.8 Ma (Curtis et al., 1975).

However, two of Charles Oxnard’s other suggestions have proved to be more durable. First, there is compelling evidence that upright bipedalism does have a deep history in the hominin clade (Richmond and Jungers, 2008). Second, there is also compelling evidence for more than one type of foot within the hominin clade and thus there must be more than one type of bipedalism within the hominin clade (Haile-Selassie et al., 2012). Oxnard’s foresight deserves more recognition than it has received.


References

Curtis, G.H., Drake, Cerling, T. and Hampel (1975) ‘Age of the KBS Tuff in Koobi For a Formation, East Rudolf, Kenya’. Nature, 258: 395-398.

Haile-Selassie, Y. et al. (2012) A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations. Nature, 483: 565-569.

Oxnard, C.E. (1973) Form and Pattern in Human Evolution: Some Mathematical, Physical, and Engineering Approaches. University of Chicago Press, Chicago.

Oxnard, C.E. (1975a) ‘The place of the australopithecines in human evolution: grounds for doubt?’ Nature, 258: 389-395.

Oxnard, C.E. (1975b) Uniqueness and Diversity in Human Evolution: Morphometric Studies of Australopithecines. University of Chicago Press, Chicago.

Oxnard, C.E. (1983) The Order of Man: A Biomathematical Anatomy of the Primates. Yale University Press, New Haven.

Oxnard, C.E. (1987) Fossils, Teeth and Sex: New Perspectives on Human Evolution. University of Washington Press, Seattle.

Richmond, B.G. and Jungers, W.L. (2008) ‘Orrorin tugenensis femoral morphology and the evolution of hominin bipedalism’. Science, 319: 1662-1665.