A Brief Update on Developments in Early Hominin ... - ACS Publications

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 29, 2018 | https://pubs.acs.org Publication Date (Web): October 15, 2013 | doi: 10.1021/bk-2013-1147.ch017

Chapter 17

A Brief Update on Developments in Early Hominin Biogeochemistry Matt Sponheimer,*,1 Julia A. Lee-Thorp,2 and Daryl Codron1,3,4 1Department

of Anthropology, 1350 Pleasant St., Hale Sciences 350/233 UCB, University of Colorado-Boulder, Boulder, Colorado 80309, U.S.A. 2Research Laboratory for Archaeology, Oxford University, Oxford OX1 3QY, United Kingdom 3Florisbad Quaternary Research, National Museum, P.O. Box 266, Bloemfontein, 9301, South Africa 4Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty, University of Zurich, 260 Winterthurestrasse, CH-8057, Zurich, Switzerland *E-mail: [email protected]

Although two decades have passed since the first biogeochemical studies of early hominin diet were published, the field has only picked up steam in the last few years. There have been major increases in available hominin carbon isotope data which allow exploration of temporal, taxonomic, and biogeographic differences in hominin diet, as well as further investigation of the relationship between diet and masticatory morphology. There have been fewer recent advances in hominin trace element studies (Sr/Ca, Ba/Ca), although evidence of intraindividual dietary variation, including a weaning signal, are likely to spur future research.

© 2013 American Chemical Society Armitage and Burton; Archaeological Chemistry VIII ACS Symposium Series; American Chemical Society: Washington, DC, 2013.


Introduction To a large extent early hominin biogeochemical studies tell a story from two viewpoints (trace elements and stable carbon isotopes) and two regions (eastern Africa and southern Africa). Until recently, almost all such work was done in South Africa (e.g., (1–3)), and while new carbon isotope data have become available from eastern Africa (4–8), there are still effectively no trace element data from that region (but see (9)). This imbalance in coverage has made it difficult to forge a coherent biogeochemical picture of hominin diet, and the imbalance is not likely to be remedied soon given concerns about diagenesis in eastern Africa (10, 11), and the increasing indifference towards trace element approaches to paleodiet among archaeometrists. Still, there has been progress, especially the massive influx of hominin carbon isotope data over the past few years (see (12)). This newfound abundance almost entirely reflects the newfound willingness of curators to allow biogeochemical analysis of fossils in their charge, rather than increased interest or effort on the part of those seeking permission to do such work. The new carbon isotope data are sufficiently intriguing that they have more than justified recent efforts, and point to unanticipated temporal, morphological, regional, and taxonomic differences in δ13C values (12). Nevertheless, most of the story of hominin diet remains to be told, and a major focus will now become what, if anything, can other biogeochemical dietary proxies add to the emerging picture from carbon isotopes? The purpose of this paper is to provide an update of recent results from carbon isotope and trace element studies of early hominins. No attempt is made to outline the basics of carbon isotopic and trace elemental studies of paleodiet as this has been done recently and at length (13). We argue that the general trends from carbon isotopes are fairly clear, and that further work in that area is likely to focus on narrower questions and, in an attempt to better interpret the carbon isotope data, a move away from stable isotopic research per se. We also argue that it is not presently clear how trace element studies will contribute to the dialog about early hominin diets, despite the fact that there appears to be evidence that biogenic patterning can be retained in fossils from some hominin sites (11). The biogeochemical data discussed herein are archived at http://figshare.com/authors/Matt_Sponheimer/99071.

Carbon Isotopes Early studies made it clear that South African australopiths ate at least some foods 13C-enriched foods such as tropical C4 grasses, C4 sedges, CAM succulents, or animals eating those plants (1, 2). This contrasts with what has been observed in chimpanzees (Pan troglodytes), which consume C3 vegetation (most trees, bushes, and forbs) even in areas with abundant C4 grasses (14, 15). Differences between hominin genera (Australopithecus, Paranthropus, Homo) were lacking (16), however, despite marked differences in masticatory morphology (17). In retrospect, perhaps the most conspicuous result of these early studies was an overall pattern of high intraspecific variability among the hominins (1–3, 18). 296 Armitage and Burton; Archaeological Chemistry VIII ACS Symposium Series; American Chemical Society: Washington, DC, 2013.


The addition of new data from southern Africa, eastern Africa, and central Africa has fleshed out the carbon isotope story (Figure 1) and has allowed new questions to be addressed. Where before the distributions of carbon isotope ratios within all hominin taxa appeared similar, as might be expected for savanna generalists, there is now evidence that hominins spanned the spectrum from almost pure C3 consumers (A. anamensis) to those with that ate few C3 resources (P. boisei), which nearly duplicates the range found among ecologically diverse bovids today (19, 20). Where before there was no evidence of dietary change through time from carbon isotopes, there now exists a strong relationship between δ13C and time among eastern African australopiths (Figure 2) (12). However, the data also intimate that there is a biogeographic tale to be told as the southern and central African data appear to be different from the eastern African data (Figure 1).

Figure 1. Early hominin taxa from southern Africa (open triangles), eastern Africa (open circles), and central Africa (closed circles) arranged from lowest to highest δ13C values. 297 Armitage and Burton; Archaeological Chemistry VIII ACS Symposium Series; American Chemical Society: Washington, DC, 2013.


Figure 2. Linear regression shows that australopith postcanine area predicts australopith δ13C values (r2=0.86, t(5)=5.50, P

A Brief Update on Developments in Early Hominin ... - ACS Publications

Recommend Documents