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Background/aim: Traumatic dental injuries (TDI) are treated by repositioning and splinting. Ideally, injured teeth should possess some mobility for optimal periodontal and pulp healing. Splints should be easy to apply in emergencies, affordable, and esthetically acceptable. The aims were to compare some clinically used splints with regard to stiffness (measured in Nm(-1)), esthetics, cost, and ease of application.Materials and Methods: Six splints were applied to dental models using an acid-etched bonding technique. One central incisor was adjusted to give 1 mm of horizontal movement at the incisal edge. The mobilized tooth was then connected to adjacent teeth with either twistflex wire (TF), titanium trauma splint (TTS), single (SFG) and double fiberglass (DFG), nylon (fishing) line (FL), or power chain (PC). A horizontal force was then gradually applied to the incisor in a standardized manner with a spherical probe (1.65 mm radius), monitoring force with a 50N load cell and displacement with a linear variable differential transformer (LVDT). Signals were amplified, converted digitally (14-bit analog-to-digital converter), and displayed in real time to show the splint stiffness. Splints were also ranked with regard to esthetics, application time needed, and ease of application cost.Results: FL and PC were the least stiff, averaging 5.7 and 6.3 Nm(-1), respectively. TTS averaged 6.9 Nm(-1), while SFG and TF averaged 18.5 and 18.4 Nm(-1), respectively. DFG was the stiffest, averaging 24.3 Nm(-1). PC and SFG were the fastest to apply. FL showed the best esthetic score, followed by TTS and PC. TTS was the most expensive splint, while FL, PC, SFG, DFG, and TF showed similar costs.Conclusions: Of these TDI splints, DFG should be avoided for flexible splinting because it is too stiff. PC may be an interesting novel alternative, affording sufficient mobility due to its low stiffness. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives The diet of tufted capuchins ( Sapajus) is characterized by annual or seasonal incorporation of mechanically protected foods. Reliance on these foods raises questions about the dietary strategies of young individuals that lack strength and experience to access these resources. Previous research has demonstrated differences between the feeding competencies of adult and juvenile tufted capuchins. Here we test the hypothesis that, compared to adults, juveniles will process foods with lower toughness and elastic moduli. Materials and Methods We present data on variation in the toughness and elastic modulus of food tissues processed by Sapajus libidinosus during the dry season at Fazenda Boa Vista, Brazil. Food mechanical property data were collected using a portable universal mechanical tester. Results Results show that food tissues processed by the capuchins showed significant differences in toughness and stiffness. However, we found no relationship between an individual's age and mean or maximum food toughness or elastic modulus, indicating both juvenile and adult S. libidinosus are able to process foods of comparable properties. Discussion Although it has been suggested that juveniles avoid mechanically protected foods, age-related differences in feeding competence are not solely due to variation in food toughness or stiffness. Other factors related to food type (e.g., learning complex behavioral sequences, achieving manual dexterity, obtaining physical strength to lift stone tools, or recognizing subtle cues about food state) combined with food mechanical properties better explain variation in juvenile feeding competency. Am J Phys Anthropol 159:199-209, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

SUMMARY Mammalian enamel, the contact dental tissue, is something of an enigma. It is almost entirely made of hydroxyapatite, yet exhibits very different mechanical behavior to a homogeneous block of the same mineral. Recent approaches suggest that its hierarchical composite form, similar to other biological hard tissues, leads to a mechanical performance that depends very much on the scale of measurement. The stiffness of the material is predicted to be highest at the nanoscale, being sacrificed to produce a high toughness at the largest scale, that is, at the level of the tooth crown itself. Yet because virtually all this research has been conducted only on human (or sometimes 'bovine') enamel, there has been little regard for structural variation of the tissue considered as evolutionary adaptation to diet. What is mammalian enamel optimized for? We suggest that there are competing selective pressures. We suggest that the structural characteristics that optimize enamel to resist large-scale fractures, such as crown failures, are very different to those that resist wear (small-scale fracture). While enamel is always designed for damage tolerance, this may be suboptimal in the enamel of some species, including modern humans (which have been the target of most investigations), in order to counteract wear. The experimental part of this study introduces novel techniques that help to assess resistance at the nanoscale. [ABSTRACT FROM AUTHOR]

Leaf defences vary widely among tree species, affecting rates of herbivory, survival and reproduction., Two contrasting hypotheses account for variation in leaf defences among species. The first predicts that a slow life history, which is characteristic of larger seeded species adapted to resource-limited environments, is associated with well-defended leaves. The second, apparency theory, predicts that elevated leaf defences are necessitated for species that are more detectable to herbivores., Here we use comparative methods and a global data set to test (i) the relationship between seed size and leaf defences and (ii) the relationship between clumping (spatial apparency) and leaf defences., We found that seed size was positively related to leaf fracture toughness, but not phenolics or tannin concentration and that spatial aggregation was unrelated to leaf defences., Synthesis. Our results suggest that larger seed size and increased leaf toughness are correlated as part of a trait syndrome associated with a slow, resource-limited life history, not clumped dispersion and increased spatial apparency. [ABSTRACT FROM AUTHOR]

ABSTRACT Recent biomechanical analyses examining the feeding adaptations of early hominins have yielded results consistent with the hypothesis that hard foods exerted a selection pressure that influenced the evolution of australopith morphology. However, this hypothesis appears inconsistent with recent reconstructions of early hominin diet based on dental microwear and stable isotopes. Thus, it is likely that either the diets of some australopiths included a high proportion of foods these taxa were poorly adapted to consume (i.e., foods that they would not have processed efficiently), or that aspects of what we thought we knew about the functional morphology of teeth must be wrong. Evaluation of these possibilities requires a recognition that analyses based on microwear, isotopes, finite element modeling, and enamel chips and cracks each test different types of hypotheses and allow different types of inferences. Microwear and isotopic analyses are best suited to reconstructing broad dietary patterns, but are limited in their ability to falsify specific hypotheses about morphological adaptation. Conversely, finite element analysis is a tool for evaluating the mechanical basis of form-function relationships, but says little about the frequency with which specific behaviors were performed or the particular types of food that were consumed. Enamel chip and crack analyses are means of both reconstructing diet and examining biomechanics. We suggest that current evidence is consistent with the hypothesis that certain derived australopith traits are adaptations for consuming hard foods, but that australopiths had generalized diets that could include high proportions of foods that were both compliant and tough. Am J Phys Anthropol 151:339-355, 2013.© 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Cell wall fibre and lamina density may interactively affect leaf toughness and leaf lifespan. Here, we tested this with seedlings of 24 neotropical tree species differing in shade tolerance and leaf lifespan under standardized field conditions (140-867 d in gaps; longer in shade). We quantified toughness with a cutting test, explicitly seeking a mechanistic linkage to fibre., Lamina density, but not fracture toughness, exhibited a plastic response to gaps vs shade, while neither trait was affected by leaf age. Toughness corrected for lamina density, a recently recognized indicator of material strength per unit mass, was linearly correlated with cellulose content per unit dry mass., Leaf lifespan was positively correlated with cellulose and toughness in shade-tolerant species but only weakly in gap-dependent species. Leaf lifespan was uncorrelated with lamina thickness, phenolics and tannin concentrations. In path analysis including all species, leaf lifespan was directly enhanced by density and toughness, and indirectly by cellulose via its effect on toughness. Different suites of leaf traits were correlated with early seedling survival in gaps vs shade., In conclusion, cellulose and lamina density jointly enhance leaf fracture toughness, and these carbon-based physical traits, rather than phenolic-based defence, explain species differences in herbivory, leaf lifespan and shade survival. [ABSTRACT FROM AUTHOR]

Primate teeth adapt to the physical properties of foods in a variety of ways including changes in occlusal morphology, enamel thickness, and overall size. We conducted a comparative study of extant primates to examine whether their teeth also adapt to foods through variation in the mechanical properties of the enamel. Nanoindentation techniques were used to map profiles of elastic modulus and hardness across tooth sections from the enamel-dentin junction to the outer enamel surface in a broad sample of primates including apes, Old World monkeys, New World monkeys, and lemurs. The measured data profiles feature considerable overlap among species, indicating a high degree of commonality in mechanical properties. These results suggest that differences in the load-bearing capacity of primate molar teeth are more a function of morphology-particularly tooth size and enamel thickness-than of underlying mechanical properties. Am J Phys Anthropol 148:171-177, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Teeth are brittle and highly susceptible to cracking. We propose that observations of such cracking can be used as a diagnostic tool for predicting bite force and inferring tooth function in living and fossil mammals. Laboratory tests on model tooth structures and extracted human teeth in simulated biting identify the principal fracture modes in enamel. Examination of museum specimens reveals the presence of similar fractures in a wide range of vertebrates, suggesting that cracks extended during ingestion or mastication. The use of 'fracture mechanics' from materials engineering provides elegant relations for quantifying critical bite forces in terms of characteristic tooth size and enamel thickness. The role of enamel microstructure in determining how cracks initiate and propagate within the enamel (and beyond) is discussed. The picture emerges of teeth as damage-tolerant structures, full of internal weaknesses and defects and yet able to contain the expansion of seemingly precarious cracks and fissures within the enamel shell. How the findings impact on dietary pressures forms an undercurrent of the study. [ABSTRACT FROM AUTHOR]

Lucas and colleagues recently proposed a model based on fracture and deformation concepts to describe how mammalian tooth enamel may be adapted to the mechanical demands of diet (Lucas et al.: Bioessays 30[20081 374-385). Here we review the applicability of that model by examining existing data on the food mechanical properties and enamel morphology of great apes (Pan, Pongo, and Gorilla). Particular attention is paid to whether the consumption of fallback foods is likely to play a key role in influencing great ape enamel morphology. Our results suggest that this is indeed the case. We also consider the implications of this conclusion on the evolution of the dentition of extinct hominins. [ABSTRACT FROM AUTHOR]

A number of living primates feed partyear on seemingly hard food objects as a failback. We ask here how hardness can be quantified and how this can help understand primate feeding ecology. We report a simple indentation methodology for quantifying hardness, elastic modulus, and toughness in the sense that materials scientists would define them. Suggested categories of fallback foods-nuts, seeds, and root vegetables-were tested, with accuracy checked on standard materials with known properties by the same means. Results were generally consistent, but the moduli of root vegetables were overestimated here. All these properties are important components of what fleidworkers mean by hardness and help understand how food properties influence primate behavior. Hardness sensu stricto determines whether foods leave permanent marks on tooth tissues when they are bitten on. The force at which a food plastically deforms can be estimated from hardness and modulus. When fallback foods are bilayered, consisting of a nutritious core protected by a hard outer coat, it is possible to predict their failure force from the toughness and modulus of the outer coat, and the modulus of the enclosed core. These forces can be high and bite forces may be maximized in fallback food consumption. Expanding the context, the same equation for the failure force for a bilayered solid can be applied to teeth. This analysis predicts that blunt cusps and thick enamel, will indeed help to sustain the integrity of teeth against contacts with these foods up to high loads. [ABSTRACT FROM AUTHOR]

This contribution investigates the evolution of diet in the Pan– Homo and hominin clades. It does this by focusing on 12 variables (nine dental and three mandibular) for which data are available about extant chimpanzees, modern humans and most extinct hominins. Previous analyses of this type have approached the interpretation of dental and gnathic function by focusing on the identification of the food consumed (i.e. fruits, leaves, etc.) rather than on the physical properties (i.e. hardness, toughness, etc.) of those foods, and they have not specifically addressed the role that the physical properties of foods play in determining dental adaptations. We take the available evidence for the 12 variables, and set out what the expression of each of those variables is in extant chimpanzees, the earliest hominins, archaic hominins, megadont archaic hominins, and an inclusive grouping made up of transitional hominins and pre-modern Homo. We then present hypotheses about what the states of these variables would be in the last common ancestor of the Pan– Homo clade and in the stem hominin. We review the physical properties of food and suggest how these physical properties can be used to investigate the functional morphology of the dentition. We show what aspects of anterior tooth morphology are critical for food preparation (e.g. peeling fruit) prior to its ingestion, which features of the postcanine dentition (e.g. overall and relative size of the crowns) are related to the reduction in the particle size of food, and how information about the macrostructure (e.g. enamel thickness) and microstructure (e.g. extent and location of enamel prism decussation) of the enamel cap might be used to make predictions about the types of foods consumed by extinct hominins. Specifically, we show how thick enamel can protect against the generation and propagation of cracks in the enamel that begin at the enamel–dentine junction and move towards the outer enamel surface. [ABSTRACT FROM AUTHOR]

• A new test for measuring leaf fracture toughness by cutting with a single inclined razor blade is described here, this having been developed to overcome some of the inadequacies of conventional double-bladed cutting tests, such as scissoring and shearing. • The accuracy and precision of this test were determined by measuring the fracture toughness of various leaf types and homogeneous films, and comparing the results with those obtained by scissoring. • The new test was found to display a low friction of cutting with great precision in measurements. Fracture toughness measurements of the specimens were considerably lower for the new test than those obtained by scissoring, owing to greater blade sharpness and reduced damage to the specimens during cutting. Despite this, the rankings of fracture toughness measurements for the specimens are similar for both the new test and scissoring, thus demonstrating the test's consistency with scissoring. • The new test was found to be successful in measuring the fracture toughness of leaf blades and other thin, film-like materials. It was also able to overcome some of the difficulties of conventional double-bladed cutting tests, especially the estimation of energy expenditure that is extraneous to the work of cutting. [ABSTRACT FROM AUTHOR]

White salty and yellow alkaline noodles were prepared raw and also as cooked for varying periods between 2 and 14 min by boiling in distilled water and then tested in tension at room temperature on a universal testing machine to characterize their stress–strain and fracture behaviors. From these tests, it was deduced that a period of∼ 7 min of cooking time for both types of noodles produced the greatest notch sensitivity. A sensory panel was constructed to evaluate the sensorily perceived optimal cooking time of these products. This perception correlated well with the notch sensitivity results obtained from the tensile tests. From a materials perspective, solids that are notch-sensitive have firm mechanical links between their structural components. Raw, undercooked and overcooked noodles variably lack this. These results suggest that notch sensitivity may be important in sensory perception and help in constructing a physical definition of “cookedness” for these types of food. [ABSTRACT FROM AUTHOR]

Ateles spp. and Alouatta spp. are often sympatric, and although they are mainly frugivorous and folivorous, respectively, they consume some of the same fruit species. However, they differ in terms of color vision, which is thought to be important for fruit detection. Alouatta spp. have routine trichromatic color vision, while Ateles spp. presents the classic polymorphism of platyrrhines: heterozygous females have trichromatic color vision, and males and homozygous females have dichromatic vision. Given these perceptual differences, one might expect Alouatta spp. to consume more reddish fruits than Ateles spp., since trichromats have an advantage for detecting fruits of that hue. Furthermore, since Ateles spp. have up to six different color vision phenotypes, as do most other platyrrhines, they might be expected to include fruits with a wider variety of hues in their diet than Alouatta spp. To test these hypotheses we studied the fruit foraging behavior of sympatric Alouatta palliata and Ateles geoffroyi in Costa Rica, and modeled the detectability of fruit via the various color vision phenotypes in these primates. We found little similarity in fruit diet between these two species (Morisita=0.086). Furthermore, despite its polymorphism, A. geoffroyi consumed more reddish fruits than A. palliata, which consumed more greenish fruits. Our modeling results suggest that most fruit species included in the diet of A. geoffroyi can be discriminated by most color vision phenotypes present in the population. These findings show that the effect of polymorphism in platyrrhines on fruit detection may not be a disadvantage for frugivory. We suggest that routine trichromacy may be advantageous for other foraging tasks, such as feeding on young leaves. Am. J. Primatol. 67:399–409, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Although most arguments explaining the predominance of polymorphic color vision in platyrrhine monkeys are linked to the advantage of trichromacy over dichromacy for foraging for ripe fruits, little information exists on the relationship between nutritional reward and performance in fruit detection with different types of color vision. The principal reward of most fruits is sugar, and thus it seems logical to investigate whether fruit coloration provides a long-distance sensory cue to primates that correlates with sugar content. Here we test the hypothesis that fruit detection performance via trichromatic color vision phenotypes provides better information regarding sugar concentration than dichromatic phenotypes (i.e., is a color vision phenotype with sufficient red-green (RG) differentiation necessary to “reveal” the concentration of major sugars in fruits?). Accordingly, we studied the fruit foraging behavior of Ateles geoffroyi by measuring both the reflectance spectra and the concentrations of major sugars in the consumed fruits. We modeled detection performance with different color phenotypes. Our results provide some support for the hypothesis. The yellow-blue (YB) color signal, which is the only one available to dichromats, was not significantly related to sugar concentration. The RG color vision signal, which is present only in trichromats, was significantly correlated with sugar content, but only when the latter was defined by glucose. There was in fact a consistent negative relationship between fruit detection performance and sucrose concentration, although this was not significant for the 430 nm and 550 nm phenotypes. The regular trichromatic phenotypes (430 nm, 533 nm, and 565 nm) showed higher correlations between fruit performance and glucose concentration than the other two trichromatic phenotypes. Our study documents a trichromatic foraging advantage in terms of fruit quality, and suggests that trichromatic color vision is advantageous over dichromatic color vision for detecting sugar-rich fruits. Am. J. Primatol. 67:411–423, 2005. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Here we describe correlations among visual ecology and the physiochemical properties of fruits and leaves consumed by four species of catarrhine primate: Cercopithecus ascanius, Colobus guereza, Pan troglodytes, and Piliocolobus badius. Collectively, their diet was diverse, with each species relying on fruits and leaves to different extents. The mean chromaticity of both foods, as perceived by the green-red and yellow-blue signals that catarrhines decode, was distinct from background foliage. However, selection on the basis of color was evident only for leaves. Primates consumed leaves with higher green-red values than the leaves they avoided–sensory mechanism that correlated with key nutritional variables, such as increased protein and reduced toughness. Moreover, the monkeys ingested leaves near dusk, when reddish targets may be more salient. Similar patterns were never observed with respect to edible fruits, the chromaticities of which did not differ from unconsumed fruits or correlate with nutritional properties. We also found that primate biomass is higher in seasonal sites. We conclude that these findings are consistent with the notion that routine trichromatic vision evolved in a context where seasonal folivory was pivotal to survival. Am. J. Primatol. 62:189-207, 2004. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Explains the presence of anthocyanins in leaves. Color distributions of young leaves; Percentage of species that flush red leaves at tropical forest sites; Measurement of upper surface color of mature and youngest leaves.

A common feature of many pollutant exposure studies is that data from these experiments often consist of either plant biomass or yield, and the response to the pollutant is usually based on a simple comparison of means determined at the end of each growing season. This type of data is now being used to quantify critical of means determined at the end of each growing season. This type of data is now being used to quantify critical levels for different types of vegetation. Such an approach is, however, inappropriate for the relatively short-term exposure studies with three since, due to their longevity, it is not possible to determine a final yield. Instead these studies should be regarded as a type of intervention experiment in which only a small part of the life cycle of the tree is investigated. Moreover, critical levels as they are now defined focus on the cumulative exposure to ozone concentrations over time. Hence, any analysis of the effects of ozone on the growth of trees should similarly focus on the behaviour of growth functions over time and not on a comparison of biomass at the end of a growing season or experiment. Here we report on the statistical analysis of a longitudinal study, where the term 'longitudinal' refers to the analysis of repeated measurements over time, and which was used to investigate relative differences in the growth of Sitka spruce and Norway spruce seedlings during three summers' exposure to ozone over three (Norway) or four (Sitka) growing seasons. Measurements of total seedling height and stem diameter were made at frequent intervals over the period of the experiment and the above-ground growth of individual trees (as log d2h) analysed for each growing season using a statistical model of the form: m(t) = a + b(t-t0). No statistically significant differences in the growth of Norway spruce were observed after three summers of ozone exposures. The growth of Sitka spruce was, however, reduced by ozone during the third growing season and in the following year, even in the absence of the pollutant. For the Sitka spruce, the fitted model was used to calculate the time a which a 10% reduction in growth had occurred in the ozone-exposed trees. In combination with ozone AOT40 indices for the relevant growing seasons, this was then used to determine a critical level of 21.3 ppm-h for this species. Since the growth of the Norway spruce was unaffected by exposure to ozone it was not possible to calculate a critical level other than to surmise that it is in excess of 30 ppm-h. [ABSTRACT FROM AUTHOR]

Two-year-old seedlings of Sitka spruce were exposed to 70 nI I-1 ozone or to filtered air over three successive summers in outdoor large-scale fumigation chambers (Solardomes). Seven months after the last period of exposure to the pollutant and just prior to budburst, upper-surface chlorisis affecting only the older needles of ozone-exposed trees was observed. In many respects, the symptoms appeared to be similar to those characteristic of type 1 spruce damage occurring in parts of mainland Europe. Chlorophyll pigments were reduced in the ozone-exposed older foliage, but no change in the ratio of chlorophylls to carotene was observed. The content of ascorbic acid was clearly related to the amount of foliar damage observed on the trees exposed to ozone and the largest increases were seen in those trees which were most visibly damaged. Although none of the foliage examined was deficient in any of the nutrient cations which were measured, the concentration of Mg in the older needles was significantly reduced by exposure to ozone, irrespective of damage symptoms. Exposure to ozone also resulted in increases in the ratios of K : Mg and Ca: Mg. In the older needles, leaching of Mg-2 and K- by 0.5 mM H2SO4, pH 3.0, was enhanced by prior exposure to ozone, but the amounts removed were small (< 6%). It is suggested that long-term exposure to ozone has a cumulative effect on plant tissue and that the observed chlorosis was the result of accelerated senescence. [ABSTRACT FROM AUTHOR]

We review here the methods by which long-tailed macaques (Macaca fascicularis fascicularis ) process seeds in Bukit Timah Nature Reserve, Singapore, and the factors that influence this. Feeding observations have revealed that these macaques either destroy seeds in their mouth with their teeth, spit them out whole from the mouth after removing much of the flesh, or else clean the flesh off them at the front of the mouth and then drop them. Absence of these observed behaviors is associated with the presence of intact seeds in the feces, indicating that macaques swallow some seeds whole. All these options were exhibited by one group of macaques and were not random alternatives; evidence links their frequency to the type of fruit (fleshy vs. Dry) and the size of the seed(s). Adaptations of the mouth of long-tailed macaques, such as gape and the presence of well-innervated cheek pouches and relatively large incisor and postcanine teeth, are predicted to influence these thresholds strongly. In a faunally depleted reserve like Bukit Timah, this dispersal is effective, but we see no evidence in this of coevolution between macaques and fruits. Many seeds in the macaque diet are probably dispersed more effectively by other vertebrates, such as birds, bats, gibbons, and civets, when these are present. However, in sites where large vertebrates have been eliminated, macaques may become important for dispersing large, large-seeded fruits. Am. J. Primatol. 45:29–44, 1998. © 1998 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

During the spring, Japanese macaques in Yakushima feed predominantly on mature leaves of trees, vines, and ferns. They are selective in which parts of leaves they eat, and this study examines potential cues and consequences of typical patterns of selection. Toughness and fiber content (NDF) were assessed for 13 of the major leaf-food species from samples collected in the spring of 1994. The toughness of the petiole, the midrib, and two parts of the lamina were tested separately. Petioles were generally the toughest part of the leaf, followed by the midribs. For both midrib and lamina, there was a positive correlation between toughness and fiber content, but the toughness of midribs was at least three times that of laminae at similar fiber contents. A clear relationship was found between the toughness of plant parts and whether or not they were eaten: no plant parts with a toughness greater than 2,300 J M² were consumed even at low fiber levels. Toughness therefore explained food selection patterns much better than did fiber content. Toughness is likely to be assessed at the front of the mouth or during mastication. However, the macaques rarely reject leaves after placing them in the mouth. We suggest, therefore, that toughness may be used to select between feeding sites, rather than between individual leaves. [ABSTRACT FROM AUTHOR]

Studies the bite forces exerted by orang-utans with their teeth in captivity. Feeding behavior; Indentation analysis; Mastication.

Objectives: The diet of tufted capuchins (Sapajus) is characterized by annual or seasonal incorporation of mechanically protected foods. Reliance on these foods raises questions about the dietary strategies of young individuals that lack strength and experience to access these resources. Previous research has demonstrated differences between the feeding competencies of adult and juvenile tufted capuchins. Here we test the hypothesis that, compared to adults, juveniles will process foods with lower toughness and elastic moduli., Materials and Methods: We present data on variation in the toughness and elastic modulus of food tissues processed by Sapajus libidinosus during the dry season at Fazenda Boa Vista, Brazil. Food mechanical property data were collected using a portable universal mechanical tester., Results: Results show that food tissues processed by the capuchins showed significant differences in toughness and stiffness. However, we found no relationship between an individual's age and mean or maximum food toughness or elastic modulus, indicating both juvenile and adult S. libidinosus are able to process foods of comparable properties., Discussion: Although it has been suggested that juveniles avoid mechanically protected foods, age-related differences in feeding competence are not solely due to variation in food toughness or stiffness. Other factors related to food type (e.g., learning complex behavioral sequences, achieving manual dexterity, obtaining physical strength to lift stone tools, or recognizing subtle cues about food state) combined with food mechanical properties better explain variation in juvenile feeding competency., (© 2015 Wiley Periodicals, Inc.)