Food mechanical properties and dietary ecology

Abstract

Interdisciplinary research has benefitted the fields of anthropology and engineering for decades: a classic example being the application of material science to the field of feeding biomechanics. However, after decades of research, discordances have developed in how mechanical properties are defined, measured, calculated, and used due to disharmonies between and within fields. This is highlighted by "toughness," or energy release rate, the comparison of incomparable tests (i.e., the scissors and wedge tests), and the comparison of incomparable metrics (i.e., the stress and displacement-limited indices). Furthermore, while material scientists report on a myriad of mechanical properties, it is common for feeding biomechanics studies to report on just one (energy release rate) or two (energy release rate and Young's modulus), which may or may not be the most appropriate for understanding feeding mechanics.Here, I review portions of materials science important to feeding biomechanists, discussing some of the basic assumptions, tests, and measurements. Next, I provide an overview of what is mechanically important during feeding, and discuss the application of mechanical property tests to feeding biomechanics. I also explain how 1) toughness measures gathered with the scissors, wedge, razor, and/or punch and die tests on non-linearly elastic brittle materials are not mechanical properties, 2) scissors and wedge tests are not comparable and 3) the stress and displacement-limited indices are not comparable. Finally, I discuss what data gathered thus far can be best used for, and discuss the future of the field, urging researchers to challenge underlying assumptions in currently used methods to gain a better understanding between primate masticatory morphology and diet. Am J Phys Anthropol 159:S79-S104, 2016. V C 2016 American Association of Physical Anthropologists "If I have seen further it is by standing on ye shoulders of Giants." Sir Isaac Newton Materials science is a branch of engineering that "involves investigating the relationships that exist between the structures and properties of materials (pg. 3, Callister (2004))," where structures are defined by the arrangement and internal components of a material (e.g., atomic structure). Over the past several decades, anthropologists and biologists have been measuring/calculating mechanical properties of dietary items to investigate differences in feeding strategies, feeding adaptations, and plant defenses (Choong et al., 1992;Hill and Lucas, 1996;Wright and Vincent, 1996;Darvell et al., 1996;Agrawal et al., 1997;Strait and Vincent, 1998;Yamashita, 1998Yamashita, , 2002Yamashita, , 2003Yamashita, , 2008Lucas et al., 2000Lucas et al., , 2001Lucas et al., , 2009Lucas et al., , 2011Agrawal and Lucas, 2003;Balsamo et al., 2003;Lucas, 2004;Elgart-Berry, 2004;Williams et al., 2005;Teaford et al., 2006;Quyet et al., 2007;Freeman and Lemen, 2007b;Wright et al., 2008;Dominy et al., 2008;Norconk et al., 2009b;Vogel et al., 2009Vogel et al., , 2014Wieczkowski, 2009;Yamas...

Beyond the Map: Enamel Distribution Characterized from 3D Dental Topography

“…This definition of hardness differs from the one used in mechanical science, in which hard objects would only resist localized plastic deformation (Berthaume, 2016). In order to avoid the confusion, this work refers to large hard food particles as stress-limited foods (Lucas et al, 2000).…”

“…Teeth are often used by mammals to ingest, reduce, and fragment food that would be difficult or even impossible to digest otherwise (Lucas, 2004; Berthaume, 2016). In turn, the physical and structural properties of the food exert a selective pressure on dental morphology, especially on enamel.…”

On modeling the large strain fracture behaviour of soft viscous foods

“…Recently, there has been a multidisciplinary interest in feeding mechanics (Wang and Chen 2017) and particularly chewing efficiency, since the latter relates to the ability of organisms to breakdown and digest food (Eng et al 2013;Bierer 2007;Drechsler and Ferrua 2016;Berthaume 2016bBerthaume , 2016a. In humans, advances in thermo-mechanical food processing alter food mechanical properties towards less masticatory effort (Eng et al 2013;Le Révérend and Hartmann 2014;Le Révérend et al 2016).…”

“…Inadequate oral breakdown can lead to maldigestion (Pera et al 2002). Chewing increases the total surface area of the food item, in order to facilitate further breakdown and enzymatic disintegration later in the gastrointestinal tract (Berthaume 2016a;Bornhorst and Singh 2012;Cleary et al 2015). This process is heavily affected by the number of food fragments and the associated average food particle size in the bolus, which is of course a function of food texture (Bornhorst and Singh 2012;Wang and Chen 2017;Drechsler and Ferrua 2016;Loret et al 2011).…”

Tooth Wear Inclination in Great Ape Molars

“…The size and shape of teeth are adapted to respond to the different functional demands required to break down foods with various phys-ical properties [Lucas, 1979;Luke and Lucas, 1983;Lucas and Luke, 1984;Dean and Benyon, 1991;Lucas and Teaford, 1994;Hillson, 2003;Pilbrow, 2007;Berthaume, 2016]. For example, primates that focus on a diet predominantly consisting of leaves are characterized by molars with high cusps, thin enamel and long shearing blades, while primates that rely on hard object foods tend to have posterior teeth with thicker enamel layers, low cusps and a generally flatter occlusal surface [Kay, 1978;Kay and Hylander, 1978;Strait, 1993;M'Kirera and Ungar, 2003;Ungar and M'Kirera, 2003;Berthaume, 2014].…”