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- Diet (2)
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Articles 1 - 6 of 6
Full-Text Articles in Life Sciences
Dental Enamel As A Dietary Indicator In Mammals, Peter Lucas, Paul Constantino, Bernard Wood, Brian Lawn
Dental Enamel As A Dietary Indicator In Mammals, Peter Lucas, Paul Constantino, Bernard Wood, Brian Lawn
Paul J. Constantino
The considerable variation in shape, size, structure and properties of the enamel cap covering mammalian teeth is a topic of great evolutionary interest. No existing theories explain how such variations might be fit for the purpose of breaking food particles down. Borrowing from engineering materials science, we use principles of fracture and deformation of solids to provide a quantitative account ofhowmammalian enamelmay be adapted to diet. Particular attention is paid to mammals that feed on ‘hard objects’ such as seeds and dry fruits, the outer casings of which appear to have evolved structures with properties similar to those of enamel. …
Adaptation To Hard-Object Feeding In Sea Otters And Hominins, Paul Constantino, James Lee, Dylan Morris, Peter Lucas, Adam Hartstone-Rose, Wah-Keat Lee, Nathaniel Dominy, Andrew Cunningham, Mark Wagner, Brian Lawn
Adaptation To Hard-Object Feeding In Sea Otters And Hominins, Paul Constantino, James Lee, Dylan Morris, Peter Lucas, Adam Hartstone-Rose, Wah-Keat Lee, Nathaniel Dominy, Andrew Cunningham, Mark Wagner, Brian Lawn
Paul J. Constantino
The large, bunodont postcanine teeth in living sea otters (Enhydra lutris) have been likened to those of certain fossil hominins, particularly the ’robust’ australopiths (genus Paranthropus). We examine this evolutionary convergence by conducting fracture experiments on extracted molar teeth of sea otters and modern humans (Homo sapiens) to determine how load-bearing capacity relates to tooth morphology and enamel material properties. In situ optical microscopy and x-ray imaging during simulated occlusal loading reveal the nature of the fracture patterns. Explicit fracture relations are used to analyze the data and to extrapolate the results from humans to earlier hominins. It is shown …
Fracture Susceptibility Of Worn Teeth, Amanda Keown, Mark Bush, James Lee, Chris Ford, Paul Constantino, Brian Lawn
Fracture Susceptibility Of Worn Teeth, Amanda Keown, Mark Bush, James Lee, Chris Ford, Paul Constantino, Brian Lawn
Paul J. Constantino
An experimental simulation study is made to determine the effects of occlusal wear on the capacity of teeth to resist fracture. Tests are carried out on model dome structures, using glass shells to represent enamel and epoxy filler to represent dentin. The top of the domes are ground and polished to produce flat surfaces of prescribed depths relative to shell thickness. The worn surfaces are then loaded axially with a hard sphere, or a hard or soft flat indenter, to represent extremes of food contacts. The loads required to drive longitudinal cracks around the side walls of the enamel to …
Morphology And Fracture Of Enamel, Sangwon Myoung, James Lee, Paul Constantino, Peter Lucas, Herzl Chai, Brian Law
Morphology And Fracture Of Enamel, Sangwon Myoung, James Lee, Paul Constantino, Peter Lucas, Herzl Chai, Brian Law
Paul J. Constantino
This study examines the inter-relation between enamel morphology and crack resistance by sectioning extracted human molars after loading to fracture. Cracks appear to initiate from tufts, hypocalcified defects at the enamel–dentin junction, and grow longitudinally around the enamel coat to produce failure. Microindentation corner cracks placed next to the tufts in the sections deflect along the tuft interfaces and occasionally penetrate into the adjacent enamel. Although they constitute weak interfaces, the tufts are nevertheless filled with organic matter, and appear to be stabilized against easy extension by self-healing, as well as by mutual stress-shielding and decussation, accounting at least in …
Microwear, Mechanics And The Feeding Adaptations Of Australopithecus Africanus, Paul Constantino, Craig Byron, Paul Dechow, Ian Gross, Peter Lucas, Brian Richmond, Callum Ross, Dennis Slice, Mark Spencer, Dennis Strait, Qian Wang, Gerhard Weber, Bernard Wood, Barth Wright
Microwear, Mechanics And The Feeding Adaptations Of Australopithecus Africanus, Paul Constantino, Craig Byron, Paul Dechow, Ian Gross, Peter Lucas, Brian Richmond, Callum Ross, Dennis Slice, Mark Spencer, Dennis Strait, Qian Wang, Gerhard Weber, Bernard Wood, Barth Wright
Paul J. Constantino
Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpretations regarding the feeding ecology and adaptations of Australopithecus africanus. As part of this debate, the methods used in the mechanical studies have been criticized. In particular, it has been claimed that finite element analysis has been poorly applied to this research question. This paper responds to some of these mechanical criticisms, highlights limitations of dental microwear analysis, and identifies avenues of future research.
Properties Of Tooth Enamel In Great Apes, Paul Constantino, Brian Lawn, James Lee, Peter Lucas, Dylan Morris, Tanya Smith
Properties Of Tooth Enamel In Great Apes, Paul Constantino, Brian Lawn, James Lee, Peter Lucas, Dylan Morris, Tanya Smith
Paul J. Constantino
A comparative study has been made of human and great ape molar tooth enamel. Nanoindentation techniques are used to map profiles of elastic modulus and hardness across sections from the enamel–dentin junction to the outer tooth surface. The measured data profiles overlap between species, suggesting a degree of commonality in material properties. Using established deformation and fracture relations, critical loads to produce function-threatening damage in the enamel of each species are calculated for characteristic tooth sizes and enamel thicknesses. The results suggest that differences in load-bearing capacity of molar teeth in primates are less a function of underlying material properties …