Paleobiological Implications of the Ardipithecus ramidus Dentition

The University Museum, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 Japan.
Science (Impact Factor: 33.61). 10/2009; 326(5949):69-99. DOI: 10.1126/science.1175824
Source: PubMed


The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus. Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.

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    • "Tooth identifications follow the same convention as the text. Measurement protocols followed Suwa et al. (2009, see their SOM). 480 L.J. HLUSKO ET AL. "

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    • "Two possible classes of food sometimes suggested to be central to early hominid diets, as noted, are animal resources and low-fiber underground storage organs (Hatley and Kappelman 1980; Milton 1987; Wrangham et al. 1999; Conklin-Brittain et al. 2002; Laden and Wrangham 2005; Yeakel et al. 2007; Dominy et al. 2008). Arguing by analogy and structural similarity to living species, both can be considered likely foods in Ardipithecus (Suwa et al. 2009) and especially Australopithecus, whose postcanine teeth strongly converge on those of bears and pigs, taxa which consume both of these gross food categories and are wellknown for their exceptionally generalist foraging strategy (Hatley and Kappelman 1980 and see below). The changes that likely occurred in gut morphology/physiology throughout human evolution, from at least as ancient a form as Australopithecus , are also consistent with, although not necessarily indicative of, exploitation of similar resources (Milton 1987; Conklin-Brittain et al. 2002; Mann 2007; Haile-Selassie et al. 2010). "
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    ABSTRACT: Beginning with Darwin, some have argued that predation on other vertebrates dates to the earliest stages of hominid evolution, and can explain many uniquely human anatomical and behavioral characters. Other recent workers have focused instead on scavenging, or particular plant foods. Foraging theory suggests that inclusion of any food is influenced by its profitability and distribution within the consumer's habitat. The morphology and likely cognitive abilities of Ardipithecus, Australopithecus, and early Homo suggest that while hunting and scavenging occurred, their profitability generally would have been considerably lower than in extant primates and/or modern human hunter-gatherers. On the other hand, early hominid diet modelers should not focus solely on plant foods, as this overlooks standard functional interpretations of the early hominid dentition, their remarkable demographic success, and the wide range of available food types within their likely day ranges. Any dietary model focusing too narrowly on any one food type or foraging strategy must be viewed with caution. We argue that early hominid diet can best be elucidated by consideration of their entire habitat-specific resource base, and by quantifying the potential profitability and abundance of likely available foods.
    The Quarterly Review of Biology 12/2014; 89(4):319-57. DOI:10.1086/678568 · 4.89 Impact Factor
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    • "The SCC is the principal mechanism (in addition to body mass) that plays a central role in male-male competition both within and between groups of higher primates. The SCC is so important in this regard that in gibbons, which live as isolated territorial pairs, the female canine has been masculinized and females have evolved a full SCC, only slightly smaller than that of their male counterparts (Suwa et al. 2009b). Yet Ardi is the only primate that until that point had abandoned the SCC as a central adaptation to successful reproduction. "

    09/2014; 70(3):337. DOI:10.3998/jar.0521004.0070.301
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