New Applications For Constrained Ordination: Reconstructing Feeding Behaviors In Fossil Remingtonocetinae (cetacea: Mammalia)
Archaeocetes; components; Constrained ordination; Eocene; eocene cetaceans; evolution; Feeding; india; Mastication; morphology; odontoceti; Reconstruction; regression; suction; transition; whales
Cooper L N; Hieronymus T L; Vinyard C J; Bajpai S; Thewissen J G M
Experimental Approaches to Understanding Fossil Organisms: Lessons from the Living
2014
1905-07
Book Chapter
n/a
Evidence of Oropharyngeal Dysfunction in Feeding in the Rat Rotenone Model of Parkinson's Disease.
Animal Studies; Deglutition – Drug Effects; Deglutition Disorders; Eating – Drug Effects; Feeding Methods; Isoflavones – Administration and Dosage; Isoflavones – Pharmacodynamics; Mastication; Oropharynx – Pathology; Parkinson Disease; Phenotype; Rats
Swallowing disorders in Parkinson's disease are not responsive to dopamine depletion therapy and contribute to morbidity. They are poorly understood owing to a lack of adequate models. We present the first evidence of oropharyngeal changes in a rotenone toxicity model of Parkinson's disease. Rats were recorded while feeding before and after daily rotenone injections at two different doses (2.75 mg/kg and 3 mg/kg). The higher dose had a much more severe parkinsonian phenotype than the low dose. Timing and amplitude of chewing changed, as did the coordination of chewing and swallowing. Dose-dependent effects were evident. These preliminary results indicate that future research in toxicological models of Parkinson's disease should incorporate the study of oropharyngeal dysfunction. A better understanding of nongenetic models of Parkinson's disease in feeding may open new avenues for research into the neurological and behavioral bases for swallowing dysfunction in Parkinson's disease.
Gould Francois D H; Gross Andrew; German Rebecca Z; Richardson Jason R
Parkinson's disease
2018
1905-07
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1155/2018/6537072" target="_blank" rel="noreferrer noopener">10.1155/2018/6537072</a>
Functional And Evolutionary Significance Of The Recruitment And Firing Patterns Of The Jaw Adductors During Chewing In Verreaux's Sifaka (propithecus Verreauxi)
Anthropology; biomechanics; bone-strain; electromyography; Evolutionary Biology; Force; fusion; lemurs lemur-catta; macaca-fascicularis; mandibular symphysis; masseter force; mastication; muscle; primates; strepsirrhines; wishboning
Jaw-muscle electromyographic (EMG) patterns indicate that compared with thick-tailed galagos and ring-tailed lemurs, anthropoids recruit more relative EMG from their balancing-side deep masseter, and that this muscle peaks late in the power stroke. These recruitment and firing patterns in anthropoids are thought to cause the mandibular symphysis to wishbone (lateral transverse bending), resulting in relatively high symphyseal stresses. We test the hypothesis that living strepsirrhines with robust, partially fused symphyses have muscle recruitment and firing patterns more similar to anthropoids, unlike those strepsirrhines with highly mobile unfused symphyses. Electromyographic (EMG) activity of the superficial and deep masseter, anterior and posterior temporalis, and medial pterygoid muscles were recorded in four dentally adult Verreaux's sifakas (Propithecus verreauxi). As predicted, we find that sifaka motor patterns are more similar to anthropoids. For example, among sifakas, recruitment levels of the balancing-side (b-s) deep masseter are high, and the b-s deep masseter fires late during the power stroke. As adult sifakas often exhibit nearly complete symphyseal fusion, these data support the hypothesis that the evolution of symphyseal fusion in primates is functionally linked to wishboning. Furthermore, these data provide compelling evidence for the convergent evolution of the wishboning motor patterns in anthropoids and sifakas. Am J Phys Anthropol 145:531-547, 2011. (C) 2011 Wiley-Liss, Inc.
Hylander W L; Vinyard C J; Wall C E; Williams S H; Johnsonl K R
American Journal of Physical Anthropology
2011
2011-08
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/ajpa.21529" target="_blank" rel="noreferrer noopener">10.1002/ajpa.21529</a>
Ternporalis Function In Anthropoids And Strepsirrhines: An Emg Study
adductor muscle force; Anthropology; biomechanics; electromyography; Evolutionary Biology; fusion; galago crassicaudatus; invivo bone strain; jaw-adductor muscle force; macaca-fascicularis; mandibular symphysis; masseter force; mastication; patterns; postorbital septum; primates; temporalis
The major purpose of this study is to analyze anterior and posterior temporalis muscle force recruitment and firing patterns in various anthropoid and strepsirrhine primates. There are two specific goals for this project. First, we test the hypothesis that in addition to transversely directed muscle force, the evolution of symphyseal fusion in primates may also be linked to vertically directed balancing-side muscle force during chewing (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). Second, we test the hypothesis of whether strepsirrhines retain the hypothesized primitive mammalian condition for the firing of the anterior temporalis, whereas anthropoids have the derived condition (Weijs [1994] Biomechanics of Feeding in Vertebrates; Berlin: Springer-Verlag, p. 282-320). Electromyographic (EMG) activities of the left and right anterior and posterior temporalis muscles were recorded and analyzed in baboons, macaques, owl monkeys, thick-tailed galagos, and ring-tailed lemurs. In addition, as we used the working-side superficial masseter as a reference muscle, we also recorded and analyzed EMG activity of the left and right superficial masseter in these primates. The data for the anterior temporalis provided no support for the hypothesis that symphyseal fusion in primates is linked to vertically directed jaw muscle forces during mastication. Thus, symphyseal fusion in primates is most likely mainly linked to the timing and recruitment of transversely directed forces from the balancing-side deep masseter (Hylander et al. [2000] Am. J. Phys. Anthropol. 112:469-492). In addition, our data demonstrate that the firing patterns for the working- and balancing-side anterior temporalis muscles are near identical in both strepsirrhines and anthropoids. Their working- and balancing-side anterior temporalis muscles fire asynchronously and reach peak activity during the power stroke. Similarly, their working- and balancing-side posterior temporalis muscles also fire asynchronously and reach peak activity during the power stroke. Compared to these strepsirrhines, however, the balancing-side posterior temporalis of anthropoids appears to have a relatively delayed firing pattern. Moreover, based on their smaller W/B ratios, anthropoids demonstrate a relative increase in muscle-force recruitment of the balancing-side posterior temporalis. This in turn suggests that anthropoids may emphasize the duration and magnitude of the power stroke during mastication. This hypothesis, however, requires additional testing. Furthermore, during the latter portion of the power stroke, the late activity of the balancing-side posterior temporalis of anthropoids apparently assists the balancing-side deep masseter in driving the working-side molars through the terminal portion of occlusion.
Hylander W L; Wall C E; Vinyard C J; Ross C; Ravosa M R; Williams S H; Johnson K R
American Journal of Physical Anthropology
2005
2005-09
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1002/ajpa.20058" target="_blank" rel="noreferrer noopener">10.1002/ajpa.20058</a>
Food Oral Processing: Conversion Of Food Structure To Textural Perception
chewing behavior; Fracture; fracture properties; fundamental mechanical parameters; human; large-deformation properties; mastication; nasal aroma; physical properties; proteins/polysaccharide mixed gels; release; rheology; sensory perception; sensory texture; time-intensity; viscoelastic model foods
Food oral processing includes all muscle activities, jaw movements, and tongue movements that contribute to preparing food for swallowing. Simultaneously, during the transformation of food structure to a bolus, a cognitive representation of food texture is formed. These physiological signals detected during oral processing are highly complex and dynamic in nature because food structure changes continuously due to mechanical and biochemical breakdown coupled with the lubricating action of saliva. Multiple and different sensations are perceived at different stages of the process. Although much work has focused on factors that determine mechanical (e. g., rheological and fracture) and sensory properties of foods, far less attention has been paid to linking food transformations that occur during oral processing with sensory perception of texture. Understanding how food structure influences specific patterns of oral processing and how these patterns relate to specific textural properties and their cognitive representations facilitates the design of foods that are nutritious, healthy, and enjoyable.
Koc H; Vinyard C J; Essick G K; Foegeding E A
Annual Review of Food Science and Technology, Vol 4
2013
2013
Book Chapter
<a href="http://doi.org/10.1146/annurev-food-030212-182637" target="_blank" rel="noreferrer noopener">10.1146/annurev-food-030212-182637</a>
Dietary signals in the premolar dentition of primates.
Adaptation; Feeding; Functional morphology; Mastication; Teeth
Dietary adaptations specific to the premolar row remain largely undocumented across primates. This study examines how relative premolar size varies among broad dietary groups (i.e., folivores, frugivores, insectivores, hard-object feeders) using a phylogenetically and ecologically diverse sample of species. We quantified relative premolar size with shape ratios computed using mandibular length, body mass, palate area, and M(1) area to evaluate hypotheses that link variation in relative premolar size to differences in tooth loading, energy requirements, the probability of tooth-food-tooth contact during mastication, and shifts in preferred bite point. Our results revealed the following dietary signals. First, primate folivores have large premolar rows relative to palate area in comparison to frugivores and insectivores. This contrast is consistent with the hypothesis that folivores require large postcanine teeth relative to the size of the oral cavity to increase the probability of particle fracture during mastication. Second, hard-object feeders are distinct from other groups in having P(4)s that are large relative to their M(1)s. This morphology is not associated with an increase in the size of the premolar row relative to mandibular length. This combination challenges the idea that hard-object feeders have large premolars as an adaptive response to resisting the loads incurred when processing mechanically challenging foods. We therefore interpret the large P(4)/M(1) ratios of hard-object feeders as indicating greater functional integration across the premolar-molar boundary owing to a mesial shift in preferred bite point. Finally, in a restricted subset of anthropoids, we found that, relative to mandibular length, premolar area increases with dietary elastic modulus (E) and toughness (R), indicating that relative premolar size is evolutionarily sensitive to food mechanical properties. Thus, our results show that relative premolar size is correlated with diet, highlighting the importance of this region for understanding the evolutionary history of primate dietary adaptations.
Scott Jeremiah E; Campbell Ryan M; Baj Luisa M; Burns Maegan C; Price Mia S; Sykes Jaime D; Vinyard Christopher J
Journal of human evolution
2018
2018-08
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1016/j.jhevol.2018.04.006" target="_blank" rel="noreferrer noopener">10.1016/j.jhevol.2018.04.006</a>
The dental microwear of hard-object feeding in laboratory Sapajus apella and its implications for dental microwear formation.
ingestion; mastication; scanning electron microscopy; dental impressions; New World monkey
OBJECTIVES: This study seeks to determine if (a) consumption of hard food items or a mixture of food items leads to the formation of premolar or molar microwear in laboratory capuchin monkeys (Sapajus apella) in one feeding session and (b) rates of microwear formation are associated with the number of food items consumed. MATERIALS AND METHODS: Five adult male capuchins were used in two experiments, one where they were fed unshelled Brazil nuts, and the other where they were fed a mixture of food items. Dental impressions were taken before and after each feeding session. Epoxy casts made from those impressions then were used in SEM analyses of rates of microwear formation. Upper and lower premolars and molars were analyzed. Qualitative comparisons were made and Spearman's rank-order correlations used to examine the relationship between rates of microwear formation and number of Brazil nuts consumed. RESULTS: Premolars and molars generally showed new microwear in the form of pits and scratches. However, the incidence of those features was low (0-6%). Rates of microwear formation were highest during the consumption of Brazil nuts. DISCUSSION: Variations in the rate of microwear formation on the premolars likely reflected patterns of ingestion whereas consistency in the rate of microwear on the molars likely reflected patterns of chewing. While dental microwear formation seemed to be correlated with the number of hard objects consumed, rates did differ between individuals. Differences in results between the two experiments demonstrate some of the limitations in our knowledge of dental microwear formation.
Teaford Mark F; Ungar Peter S; Taylor Andrea B; Ross Callum F; Vinyard Christopher J
American journal of physical anthropology
2020
2020-03
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
Journal Article
<a href="http://doi.org/10.1002/ajpa.24000" target="_blank" rel="noreferrer noopener">10.1002/ajpa.24000</a>
The Influence of Experimental Manipulations on Chewing Speed During In Vivo Laboratory Research in Tufted Capuchins (Cebus apella)
anthropoid primates; Anthropology; bone strain; elastic model foods; Evolutionary Biology; experimental conditions; human mastication; jaw-muscle electromyography; lemurs lemur-catta; macaca-fascicularis; mandibular corpus; mastication; national-park; platyrrhine; symphyseal fusion
Even though in vivo studies of mastication in living primates are often used to test functional and adaptive hypotheses explaining primate masticatory behavior, we currently have little data addressing how experimental procedures performed in the laboratory influence mastication. The obvious logistical issue in assessing how animal manipulation impacts feeding physiology reflects the difficulty in quantifying mechanical parameters without handling the animal. In this study, we measured chewing cycle duration as a mechanical variable that can be collected remotely to: 1) assess how experimental manipulations affect chewing speed in Cebus apella, 2) compare captive chewing cycle durations to that of wild conspecifics, and 3) document sources of variation (beyond experimental manipulation) impacting captive chewing cycle durations. We find that experimental manipulations do increase chewing cycle durations in C. apella by as much as 152 milliseconds (ms) on average. These slower chewing speeds are mainly an effect of anesthesia (and/or restraint), rather than electrode implantation or more invasive surgical procedures. Comparison of captive and wild C. apella suggest there is no novel effect of captivity on chewing speed, although this cannot unequivocally demonstrate that masticatory mechanics are similar in captive and wild individuals. Furthermore, we document significant differences in cycle durations due to inter-individual variation and food type, although duration did not always significantly correlate with mechanical properties of foods. We advocate that the significant reduction in chewing speed be considered as an appropriate qualification when applying the results of laboratory-based feeding studies to adaptive explanations of primate feeding behaviors. Am J Phys Anthropol 145: 402-414, 2011. (C) 2011 Wiley-Liss, Inc.
Thompson C L; Donley E M; Stimpson C D; Horne W I; Vinyard C J
American Journal of Physical Anthropology
2011
2011-07
Journal Article
<a href="http://doi.org/10.1002/ajpa.21514" target="_blank" rel="noreferrer noopener">10.1002/ajpa.21514</a>
Using electromyography as a research tool in food science
chewing behavior; emg; Food Science & Technology; force; mastication; muscle; normalization; patterns; release; surface electromyography; texture-perception
The jaw muscles play key functional roles during feeding. During contraction, a bioelectrical signal propagates along the muscle cell helping to coordinate muscle contraction. This signal can be measured via electromyography (EMG). Food scientists have increasingly adopted EMG as a tool for studying the relationships among food textures and oral processing. Specifically, food scientists have used EMG from the feeding muscles as (1) a general measure of food texture, (2) a measure of oral physiology, (3) an estimate of absolute force and (4) a measure of muscle work. Unfortunately, physiological research indicates that estimates of absolute force and mechanical work are not reliably indicated from EMG as it is best considered an indicator of muscle activity and relative recruitment levels.
Vinyard C J; Fiszman S
Current Opinion in Food Science
2016
2016-06
Journal Article
<a href="http://doi.org/10.1016/j.cofs.2016.06.003" target="_blank" rel="noreferrer noopener">10.1016/j.cofs.2016.06.003</a>
Methods for Studying the Ecological Physiology of Feeding in Free-Ranging Howlers (Alouatta palliata) at La Pacifica, Costa Rica
adductor muscle force; fecal cortisol-levels; Feeding ecology; in-vivo; Jaw-muscle physiology; lemurs lemur-catta; macaca-fascicularis; mandibular function; mastication; mechanical defenses; postorbital septum; Research methods; symphyseal fusion; telemetry system; Zoology
We lack a general understanding of how primates perform physiologically during feeding to cope with the challenges of their natural environments. We here discuss several methods for studying the ecological physiology of feeding in mantled howlers (Alouatta palliata) at La Pacifica, Costa Rica. Our initial physiological effort focuses on recording electromyographic activity (EMG) from the jaw muscles in free-ranging howlers while they feed in their natural forest habitat. We integrate these EMG data with measurements of food material properties, dental wear rates, as well as spatial analyses of resource use and food distribution. Future work will focus on incorporating physiological measures of bone deformation, i.e., bone strain; temperatures; food nutritional data; and hormonal analyses. Collectively, these efforts will help us to better understand the challenges that howlers face in their environment and the physiological mechanisms they employ during feeding. Our initial efforts provide a proof of concept demonstrating the methodological feasibility of studying the physiology of feeding in free-ranging primates. Although howlers offer certain advantages to in vivo field research, many of the approaches described here can be applied to other primates in natural habitats. By collecting physiological data simultaneously with ecological and behavioral data, we will promote a more synthetic understanding of primate feeding and its evolutionary history.
Vinyard C J; Glander K E; Teaford M F; Thompson C L; Deffenbaugh M; Williams S H
International Journal of Primatology
2012
2012-06
Journal Article
<a href="http://doi.org/10.1007/s10764-012-9579-2" target="_blank" rel="noreferrer noopener">10.1007/s10764-012-9579-2</a>
Preference and consequences: A preliminary look at whether preference impacts oral processing in non-human primates
Anthropology; bitter taste; cebus-apella; chewing behavior; electromyography; Evolutionary Biology; fallback foods; Feeding; Food mechanical properties; Food preference; hardness; mastication; mechanical properties; model foods; muscle; patterns; texture
Non-human primates demonstrate food preferences much like humans. We have little insight, however, into how those preferences impact oral processing in primates. To begin describing this relationship, we conducted a preliminary analysis measuring food preference in two tufted capuchins (Cebus apella) and comparing ranked preference to physiological variables during chewing of these foods. Food preference was assessed for each monkey across 12 foods, including monkey biscuits and 11 foods consumed by humans (e.g., various fruits and nuts). Animals chose from randomized pairs of foods to generate a ranked scale across the 12 foods. Contemporaneous with preference testing, electromyographic (EMG) activity was measured for the jaw-closing muscles to assess oral physiology during chewing of these foods. As expected, these capuchins exhibited clear preferences among these 12 foods. Based on their preferences, we identified sets of preferred and non-preferred brittle (i.e., almond versus monkey chow) and ductile (i.e., dates and prunes versus apricots) foods for physiological comparisons that broadly control variation in food mechanical properties (FMPs). As expected, oral physiology varied with FMPs in each animal. Within brittle and ductile groupings, we observed several significant differences in chewing cycle length and relative muscle activation levels that are likely related to food preference. These differences tended to be complex and individual specific. The two capuchins chewed non-preferred apricots significantly faster than preferred dates and prunes. Effect sizes for preference were smaller than those for FMPs, supporting the previous focus on FMPs in primate dietary research. Although preliminary, these results suggest that food preference may influence oral physiology in non-human primates. The prospect that this relationship exists in monkeys raises the possibility that a link between food preference and oral processing in humans may be based on shared tendencies with non-human primates, such as aversion to bitter items or preference for sweet foods. (C) 2016 Elsevier Ltd. All rights reserved.
Vinyard C J; Thompson C L; Doherty A; Robl N
Journal of Human Evolution
2016
2016-09
Journal Article
<a href="http://doi.org/10.1016/j.jhevol.2016.07.001" target="_blank" rel="noreferrer noopener">10.1016/j.jhevol.2016.07.001</a>
Phase II jaw movements and masseter muscle activity during chewing in Papio anubis
adaptations; Anthropology; bone strain; dentition; emg; evolution; Evolutionary Biology; jaw muscles; loading patterns; macaca-fascicularis; macaques; mastication; power stroke; primates; teeth
It was proposed that the power stroke in primates has two distinct periods of occlusal contact, each with a characteristic motion of the mandibular molars relative to the maxillary molars. The two movements are called phase I and phase IT, and they occur sequentially in that order (Kay and Hiiemae [1974] Am J. Phys. Anthropol. 40:227-256, Kay and Hiiemae [1974] Prosimian Biology, Pittsburgh: University of Pittsburgh Press, p. 501-530). Phase I movement is said to be associated with shearing along a series of crests, producing planar phase I facets and crushing on surfaces on the basins of the molars. Phase I terminates in centric occlusion. Phase II movement is said to be associated with grinding along the same surfaces that were used for crushing at the termination of phase I. Hylander et al. ([1987] Am J. Phys. Anthropol. 72:287-312; see also Hiiemae [1984] Food Acquisition and Processing, London: Academic Press, p. 257-281; Hylander and Crompton [1980] Am J. Phys. Anthropol. 52:239-251, [1986] Arch. Oral. Biol. 31:841-848) analyzed data on macaques and suggested that phase IT movement may not be nearly as significant for food breakdown as phase I movement simply because, based on the magnitude of mandibular bone strain patterns, adductor muscle and occlusal forces are likely negligible during movement out of centric occlusion. Our goal is to better understand the functional significance of phase IT movement within the broader context of masticatory kinematics during the power stroke. We analyze vertical and transverse mandibular motion and relative activity of the masseter and temporalis muscles during phase I and II movements in Papio anubis. We test whether significant muscle activity and, by inference, occlusal force occurs during phase IT movement. We find that during phase IT movement, there is negligible force developed in the superficial and deep masseter and the anterior and posterior temporalis muscles. Furthermore, mandibular movements are small during phase II compared to phase I. These results suggest that grinding during phase IT movement is of minimal importance for food breakdown, and that most food breakdown on phase IT facets occurs primarily at the end of phase I movement (i.e., crushing during phase I movement). We note, however, that depending on the orientation of phase I facets, significant grinding also occurs along phase I facets during phase I. (c) 2005 Wiley-Liss, Inc.
Wall C E; Vinyard C J; Johnson K R; Williams S H; Hylander W L
American Journal of Physical Anthropology
2006
2006-02
Journal Article
<a href="http://doi.org/10.1002/ajpa.20290" target="_blank" rel="noreferrer noopener">10.1002/ajpa.20290</a>
Mandibular corpus bone strain in goats and alpacas: Implications for understanding the biomechanics of mandibular form in selenodont artiodactyls
adductor muscle force; Anatomy & Morphology; bone strain; functional-significance; jaw; macaca-fascicularis; mandibles; mandibular corpus; mastication; masticatory biomechanics; morphology; movements; stress; symphyseal fusion
The goal of this study is to clarify the functional and biomechanical relationship between jaw morphology and in vivo masticatory loading in selenodont artiodactyls. We compare in vivo strains from the mandibular corpus of goats and alpacas to predicted strain patterns derived from biomechanical models for mandibular corpus loading during mastication. Peak shear strains in both species average 600-700 mu epsilon on the working side and approximately 450 mu epsilon on the balancing side. Maximum principal tension in goats and alpacas is directed at approximately 30 degrees dorsocaudally relative to the long axis of the corpus on the working side and approximately perpendicular to the long axis on the balancing side. Strain patterns in both species indicate primarily torsion of the working-side corpus about the long axis and parasagittal bending and/or lateral transverse bending of the balancing-side corpus. Interpretation of the strain patterns is consistent with comparative biomechanical analyses of jaw morphology suggesting that in goats, the balancing-side mandibular corpus is parasagittally bent whereas in alpacas it experiences lateral transverse bending. However, in light of higher working-side corpus strains, biomechanical explanations of mandibular form also need to consider that torsion influences relative corpus size and shape. Furthermore, the complex combination of loads that occur along the selenodont artiodactyl mandibular corpus during the power stroke has two implications. First, added clarification of these loading patterns requires in vivo approaches for elucidating biomechanical links between mandibular corpus morphology and masticatory loading. Second, morphometric approaches may be limited in their ability to accurately infer masticatory loading regimes of selenodont artiodactyl jaws.
Williams S H; Vinyard C J; Wall C E; Hylander W L
Journal of Anatomy
2009
2009-01
Journal Article
<a href="http://doi.org/10.1111/j.1469-7580.2008.01008.x" target="_blank" rel="noreferrer noopener">10.1111/j.1469-7580.2008.01008.x</a>
Telemetry System for Assessing Jaw-Muscle Function in Free-ranging Primates
Alouatta; analysis; biomechanical; bone strain; electromyography; food properties; form; galago crassicaudatus; macaca-fascicularis; mandibular symphysis; mastication; morphology; old-world monkeys; telemetry; Zoology
In vivo laboratory-based studies describing jaw-muscle activity and mandibular bone strain during mastication provide the empirical basis for most evolutionary hypotheses linking primate masticatory apparatus form to diet. However, the laboratory data pose a potential problem for testing predictions of these hypotheses because estimates of masticatory function and performance recorded in the laboratory may lack the appropriate ecological context for understanding adaptation and evolution. For example, in laboratory studies researchers elicit rhythmic chewing using foods that may differ significantly from the diets of wild primates. Because the textural and mechanical properties of foods influence jaw-muscle activity and the resulting strains, chewing behaviors studied in the laboratory may not adequately reflect chewing behaviors of primates feeding in their natural habitats. To circumvent this limitation of laboratory-based studies of primate mastication, we developed a system for recording jaw-muscle electromyograms (EMGs) from free-ranging primates so that researchers can conduct studies of primate jaw-muscle function in vivo in the field. We used the system to record jaw-muscle EMGs from mantled howlers (Alouatta palliata) at Hacienda La Pacifica, Costa Rica. These are the first EMGs recorded from a noncaptive primate feeding in its natural habitat. Further refinements of the system will allow long-term EMG data collection so that researchers can correlate jaw-muscle function with food mechanical properties and behavioral observations. In addition to furthering understanding of primate feeding biology, our work will foster improved adaptive hypotheses explaining the evolution of primate jaw form.
Williams S; Vinyard C; Glander K; Deffenbaugh M; Teaford M; Thompson C
International Journal of Primatology
2008
2008-12
Journal Article
<a href="http://doi.org/10.1007/s10764-008-9292-3" target="_blank" rel="noreferrer noopener">10.1007/s10764-008-9292-3</a>