Hominins, sedges, and termites: New carbon isotope data from the Sterkfontein Valley and Kruger National Park. J Hum Evol 48: 301-312

Institute for Neuroscience, University of Texas at Austin, Austin, Texas, United States
Journal of Human Evolution (Impact Factor: 3.73). 04/2005; 48(3):301-12. DOI: 10.1016/j.jhevol.2004.11.008
Source: PubMed


Stable carbon isotope analyses have shown that South African australopiths did not have exclusively frugivorous diets, but also consumed significant quantities of C4 foods such as grasses, sedges, or animals that ate these foods. Yet, these studies have had significant limitations. For example, hominin sample sizes were relatively small, leading some to question the veracity of the claim for australopith C4 consumption. In addition, it has been difficult to determine which C4 resources were actually utilized, which is at least partially due to a lack of stable isotope data on some purported australopith foods. Here we begin to address these lacunae by presenting carbon isotope data for 14 new hominin specimens, as well as for two potential C4 foods (termites and sedges). The new data confirm that non-C3 foods were heavily utilized by australopiths, making up about 40% and 35% of Australopithecus and Paranthropus diets respectively. Most termites in the savanna-woodland biome of the Kruger National Park, South Africa, have intermediate carbon isotope compositions indicating mixed C3/C4 diets. Only 28% of the sedges in Kruger were C4, and few if any had well-developed rhizomes and tubers that make some sedges attractive foods. We conclude that although termites and sedges might have contributed to the C4 signal in South African australopiths, other C4 foods were also important. Lastly, we suggest that the consumption of C4 foods is a fundamental hominin trait that, along with bipedalism, allowed australopiths to pioneer increasingly open and seasonal environments.

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    • "Apparently they do not. Isotope analyses imply that P. robustus consumed greater amounts of C 3 sources than P. boisei: it overlaps entirely in its isotope composition with Australopithecus africanus (Sponheimer et al., 2005; Lee-Thorp et al., 2010), but not in microwear texture (Scott et al., 2005). Inspection RI PLFURZHDU WH[WXUHV SURYLGHG E\ *ULQH et al. (2012) reveals P. robustus to be unique amongst extant and extinct primates, i.e., it does not unequivocally cluster with any other extant primate analysed thus far. "
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    ABSTRACT: The dietary ecology of early hominins, particularly East and South African Paranthropus, remains poorly understood. Here I argue that an integrative approach that combines current knowledge on isotope composition, microwear textures, dental morphology and comparative studies on the extant baboon Papio cynocephalus has the potential to shed light on the possible diet(s) of Paranthropus boisei and P. robustus. Baboons eat a variety of C 4 foods, which differ considerably in nutritional value and material properties. East and South African paranthropines apparently spent longer periods of time feeding on similar C 4 foods; their morphology suggests that they exploited opposite ends of the C 4 plant food niche spectrum that is utilised by baboons. Paranthropus boisei consumed predominantly hard brittle foods, while P. robustus fed on hard tough resources. Because of the high nutrional value of some C 4 foods, a shift in dietary preferences from C 3 to C 4 sources need not have been accompanied by an extension of total feeding time. To what extent differences in food selection and time spent feeding on C 4 foods between P. boisei and P. robustus were due to habitat differences between East and South Africa, or constitute true species preferences, needs to be investigated further.
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    • "Plants adapted to the gradual cooling environment of the Neogene with the rise of many C4 lineages in parallel (Christin et al., 2011; Sage et al., 2011), with the grasses in particular predisposed to C4 evolution (Christin et al., 2013). The expansion of C4-dominated savannahs during the cooling latter stages of the Pliocene 2.8e2.4 mya (millions of years ago) is associated with an increase in the consumption of C4 foods in the diet of hominins such as Australopithecus afarensis, reflecting a greater dependence on warm season grasses and sedges as well as C4-grazing animals (Sponheimer and Lee-Thorp, 1999; Sponheimer et al., 2005, 2013; Lee-Thorp et al., 2010; Wynn et al., 2013; Cerling et al., 2013a, b). Whether this shift involved an increase in the direct exploitation of plants is still unknown, but the dietary shift of the time has been associated with major episodes in brain and digestive evolution in the genus Homo (Aiello and Wheeler, 1995). "
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    ABSTRACT: The colonization of the human environment by plants, and the consequent evolution of domesticated forms is increasingly being viewed as a co-evolutionary plant–human process that occurred over a long time period, with evidence for the co-evolutionary relationship between plants and humans reaching ever deeper into the hominin past. This developing view is characterized by a change in emphasis on the drivers of evolution in the case of plants. Rather than individual species being passive recipients of artificial selection pressures and ultimately becoming domesticates, entire plant communities adapted to the human environment. This evolutionary scenario leads to systems level genetic expectations from models that can be explored through ancient DNA and Next Generation Sequencing approaches. Emerging evidence suggests that domesticated genomes fit well with these expectations, with periods of stable complex evolution characterized by large amounts of change associated with relatively small selective value, punctuated by periods in which changes in one-half of the plant–hominin relationship cause rapid, low-complexity adaptation in the other. A corollary of a single plant–hominin co-evolutionary process is that clues about the initiation of the domestication process may well lie deep within the hominin lineage.
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    • "Implications of seasonal extractive foraging for hominin evolution Although the fossil record is expected to obscure the effects of seasonality on behavior, stable isotope analyses indicate seasonal variation in diet for at least one hominin, Paranthropus robustus (Sponheimer et al., 2006). This variation agrees well with evidence of tool use for extractive foraging by South African hominins, including P. robustus (Backwell and d'Errico, 2001; d'Errico and Backwell, 2009) and C 4 isotopic signatures of some extractable foods such as termites and plant underground storage organs (Sponheimer et al., 2005; Yeakel et al., 2007; Dominy et al., 2008). Perhaps compellingly, the consumption of termites by modern chimpanzees, an important referential model, is seasonal and especially important in harsh environments (McGrew, 1979; McGrew and Collins, 1985; Moore, 1996; Bogart and Pruetz, 2008). "
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    ABSTRACT: The parallel evolution of increased sensorimotor intelligence in humans and capuchins has been linked to the cognitive and manual demands of seasonal extractive faunivory. This hypothesis is attractive on theoretical grounds, but it has eluded widespread acceptance due to lack of empirical data. For instance, the effects of seasonality on the extractive foraging behaviors of capuchins are largely unknown. Here we report foraging observations on four groups of wild capuchins (Cebus capucinus) inhabiting a seasonally dry tropical forest. We also measured intra-annual variation in temperature, rainfall, and food abundance. We found that the exploitation of embedded or mechanically protected invertebrates was concentrated during periods of fruit scarcity. Such a pattern suggests that embedded insects are best characterized as a fallback food for capuchins. We discuss the implications of seasonal extractive faunivory for the evolution of sensorimotor intelligence (SMI) in capuchins and hominins and suggest that the suite of features associated with SMI, including increased manual dexterity, tool use, and innovative problem solving are cognitive adaptations among frugivores that fall back seasonally on extractable foods. The selective pressures acting on SMI are predicted to be strongest among primates living in the most seasonal environments. This model is proffered to explain the differences in tool use between capuchin lineages, and SMI as an adaptation to extractive foraging is suggested to play an important role in hominin evolution.
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