Tooth use and the physical properties of food

Strait, Suzanne G.

doi:10.1002/(sici)1520-6505(1997)5:6<199::aid-evan2>3.0.co;2-8

Cited by 116 publications

(60 citation statements)

References 48 publications

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“…Variations in tooth shape are a means of adapting to changes in the internal characteristics of foods, such as their strength, toughness, and deformability (39)(40)(41)(42)(43). Clearly, foods are complicated structures; thus it is impossible to describe all of the internal characteristics that might have confronted the earliest hominids' teeth.…”

Section: Tooth Shapementioning

confidence: 65%

Diet and the evolution of the earliest human ancestors

Teaford

Ungar

2000

Proc. Natl. Acad. Sci. U.S.A.

421

230

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Over the past decade, discussions of the evolution of the earliest human ancestors have focused on the locomotion of the australopithecines. Recent discoveries in a broad range of disciplines have raised important questions about the influence of ecological factors in early human evolution. Here we trace the cranial and dental traits of the early australopithecines through time, to show that between 4.4 million and 2.3 million years ago, the dietary capabilities of the earliest hominids changed dramatically, leaving them well suited for life in a variety of habitats and able to cope with significant changes in resource availability associated with long-term and short-term climatic fluctuations. Since the discovery of Australopithecus afarensis, many researchers have emphasized the importance of bipedality in scenarios of human origins (1,2). Surprisingly, less attention has been focused on the role played by diet in the ecology and evolution of the early hominids (as usually received). Recent work in a broad range of disciplines, such as paleoenvironmental studies (3, 4), behavioral ecology (5), primatology (6), and isotope analyses (7), has rekindled interests in early hominid diets. Moreover, important new fossils from the early Pliocene raise major questions about the role of dietary changes in the origins and early evolution of the Hominidae (8-10). In short, we need to focus not just on how the earliest hominids moved between food patches, but also on what they ate when they got there.This paper presents a review of the fossil evidence for the diets of the Pliocene hominids Ardipithecus ramidus, Australopithecus anamensis, Australopithecus afarensis, and Australopithecus africanus. These hominids offer evidence for the first half of human evolution, from our split with prehistoric apes to the earliest members of our own genus, Homo. The taxa considered are viewed as a roughly linear sequence from Ardipithecus to A. africanus, spanning the time from 4.4 million to 2.5 million years ago. As such, they give us a unique opportunity to examine changes in dietary adaptations of our ancestors over nearly 2 million years. We also trace what has been inferred concerning the diets of the Miocene hominoids to put changes in Pliocene hominid diets into a broader temporal perspective. From such a perspective, it becomes clear that the dietary capabilities of the early hominids changed dramatically in the time period between 4.4 million and 2.3 million years ago. Most of the evidence has come from five sources: analyses of tooth size, tooth shape, enamel structure, dental microwear, and jaw biomechanics. Taken together, they suggest a dietary shift in the early australopithecines, to increased dietary flexibility in the face of climatic variability. Moreover, changes in diet-related adaptations from A. anamensis to A. afarensis to A. africanus suggest that hard, abrasive foods became increasingly important through the Pliocene, perhaps as critical items in the diet. Tooth SizeIn 1970, Jolly (11) noted that australopithec...

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Section: Tooth Shapementioning

confidence: 65%

Diet and the evolution of the earliest human ancestors

Teaford

Ungar

2000

Proc. Natl. Acad. Sci. U.S.A.

421

230

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“…Angularity is a measure of jaggedness or change in slope across a surface rather than steepness per se. This finding is consistent with the expectation that a more folivorous form should have more angular surfaces for shearing and slicing tough leaves than a frugivore that needs a flatter, less angular surface for crushing and grinding fruits (20,21). The lack of interaction between wear stage and taxon suggests that differences in angularity are maintained between species throughout the wear sequence.…”

Section: Discussionmentioning

confidence: 99%

A solution to the worn tooth conundrum in primate functional anatomy

Ungar

M’Kirera

2003

Proc. Natl. Acad. Sci. U.S.A.

161

205

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Worn teeth are a bane to paleobiologists interested in the diets of human ancestors and other fossil primates. Although worn teeth dominate fossil assemblages, their shapes are usually not used to reconstruct the diets of extinct species. The problem is that traditional studies of primate dental functional anatomy have focused on unworn morphology. This has limited most functional analyses to only a few well-represented fossil species. This paper introduces a method to characterize and compare worn occlusal morphology in primates using laser scanning and geographic information systems technologies. A study of variably worn chimpanzee and gorilla molars indicates that differences between these species in tooth shape remain consistent at given stages of wear. Although cusp slope decreases with wear in both taxa, angularity values remain unchanged. These results indicate that African ape teeth wear in a manner that keeps them mechanically efficient for fracturing specific foods. Studies of changes in tooth shape with wear add a new dimension to dental functional anatomy, and offer a more complete picture of dental-dietary adaptations. Also, given how rare unworn teeth are in the fossil record, the ability to include worn specimens in analyses opens the door to reconstructing the diets of many more extinct primate groups, allowing us to better understand the adaptive radiation of our order.

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“…A comprehensive understanding of the feeding biomechanics and dental functional anatomy of living anthropoids is required to accurately reconstruct the diets of fossil primates. Although considerable attention has been devoted to the functional morphology of living and fossil anthropoid molars and premolars (Groves and Napier, 1968;Kay, 1978;Lucas, 1980Lucas, , 1982Wood et al, 1983;Benyon, 1986;Ungar and Kay, 1995;Kay and Ungar, 1997;Benyon et al, 1998;Strait, 1998;Ungar, 1998;Smith, 1999;Ungar and Kiera, 2003;Teaford, 2007;Skinner et al, 2008;Kupczik et al, 2009) comparatively little is known about the functional morphology of anthropoid incisors.…”

Section: Introductionmentioning

confidence: 99%

“…1). Therefore, the correlation between pronounced incisal curvature and frugivorous diets among anthropoids is consistent with the hypothesis that MD and CI crown curvature function to resist the elevated occlusal loading and bending stresses associated with frugivory (Lucas and Teaford, 1994;Ungar, 1995;Strait, 1998;Elgart-Berry, 2004;Lucas, 2004;Wright, 2005;Norconk et al, 2009). Alternatively, increased incisor crown curvature may (i) function to resist dental wear by increasing the relative incisor crown surface area, (ii) increase dietary efficiency by optimizing incisor orientation and occlusion, (iii).…”

Section: Introductionmentioning

confidence: 99%

Incisor Crown Bending Strength Correlates With Diet and Incisor Curvature in Anthropoid Primates

Deane

2014

The Anatomical Record

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Anthropoid incisors are large relative to the postcanine dentition and function in the preprocessing of food items. Previous analyses of anthropoid incisor allometry and shape demonstrate that incisor morphology is correlated with preferred foods and that more frugivorous anthropoids have larger and more curved incisors. Although the relationship between incisal crown curvature and preferred foods has been well documented in extant and fossil anthropoids, the functional significance of curvature variation has yet to be conclusively established. Given that an increase in crown curvature will increase maximum linear crown dimensions, and bending resistance is a function of linear crown dimensions, it is hypothesized that incisor crown curvature functons to increase incisor crown resistance to bending forces. This study uses beam theory to calculate the mesiodistal and labiolingual bending strengths of the maxillary and mandibular incisors of hominoid and platyrrhine taxa with differing diets and variable degrees of incisal curvature. Results indicate that bending strength correlates with incisal curvature and that frugivores have elevated incisor bending resistance relative to folivores. Maxillary central incisor bending strengths further discriminate platyrrhine and hominoid hardand soft-object frugivores suggesting this crown is subjected to elevated occlusal loading relative to other incisors. These results are consistent with the hypothesis that incisor crown curvature functions to increase incisor crown resistance to bending forces but does not preclude the possibility that incisor bending strength is a composite function of multiple dentognathic variables including, but not limited to, incisor crown curvature.

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Tooth use and the physical properties of food

Cited by 116 publications

References 48 publications

Diet and the evolution of the earliest human ancestors

Diet and the evolution of the earliest human ancestors

A solution to the worn tooth conundrum in primate functional anatomy

Incisor Crown Bending Strength Correlates With Diet and Incisor Curvature in Anthropoid Primates

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