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1. Relationships between sex, body mass and tooth wear in Cayo Santiago rhesus monkeys (Macaca mulatta)

   Guatelli-Steinberg, Debbie; Maldonado, Elizabeth; Kensler, Terry B; Kohn, Luci AP; Zhao, Martin Q; Wang, Q. (January 2021, American journal of physical anthropology)

   null (Ed.)

   Understanding factors affecting tooth wear in primates is of interest because as teeth wear, their chewing efficiency can change—in some species positively and in others negatively. It is well known that teeth wear with age, but relationships between sex and tooth wear and between body size and tooth wear are less well understood. Here we analyze molar wear scores from a cross-sectional sample of 212 Cayo Santiago rhesus monkey (Macaca mulatta) adults examined in 1985. Because males are generally larger than females --potentially processing more food over their lifetimes--we hypothesized that with age included in an ordinal logistic regression model, males would exhibit significantly greater wear than females. We further hypothesized that males of larger body mass would exhibit greater wear than males of smaller body mass. Finally, because many of the females were pregnant or lactating at the time of dental examination, we hypothesized that there would be no relationship between body mass and wear in females. We found that with age included in ordinal logistic regression models, males had significantly more worn molars than females, larger males had more worn molars than smaller males, and that for females, molar wear was not significantly related to body mass. These results suggest that over the life course, animals with larger body sizes (males vs. females and larger vs. smaller males) may accumulate more wear than those with smaller body sizes. Future analyses to be conducted on the Cayo Santiago monkeys’ skeletal remains will further evaluate this possibility. Funding Sources: The Cayo Santiago colony is supported by NIH 5P40OD012217. This project is supported by NSF grants to DG-S., LK., MZ, and QW (NSF #1926528, 1926481, 1926402, and 1926601). 

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2. Relationships between sex, body mass and tooth wear in Cayo Santiago rhesus monkeys (Macaca mulatta)

   Guatelli-Steinberg, Debbie; Maldonado, Elizabeth; Kensler, Terry B; Kohn, Luci AP; Zhao, Martin Q; Wang, Q. (January 2021, American journal of physical anthropology)

   null (Ed.)

   Understanding factors affecting tooth wear in primates is of interest because as teeth wear, their chewing efficiency can change—in some species positively and in others negatively. It is well known that teeth wear with age, but relationships between sex and tooth wear and between body size and tooth wear are less well understood. Here we analyze molar wear scores from a cross-sectional sample of 212 Cayo Santiago rhesus monkey (Macaca mulatta) adults examined in 1985. Because males are generally larger than females --potentially processing more food over their lifetimes--we hypothesized that with age included in an ordinal logistic regression model, males would exhibit significantly greater wear than females. We further hypothesized that males of larger body mass would exhibit greater wear than males of smaller body mass. Finally, because many of the females were pregnant or lactating at the time of dental examination, we hypothesized that there would be no relationship between body mass and wear in females. We found that with age included in ordinal logistic regression models, males had significantly more worn molars than females, larger males had more worn molars than smaller males, and that for females, molar wear was not significantly related to body mass. These results suggest that over the life course, animals with larger body sizes (males vs. females and larger vs. smaller males) may accumulate more wear than those with smaller body sizes. Future analyses to be conducted on the Cayo Santiago monkeys’ skeletal remains will further evaluate this possibility. Funding Sources: The Cayo Santiago colony is supported by NIH 5P40OD012217. This project is supported by NSF grants to DG-S., LK., MZ, and QW (NSF #1926528, 1926481, 1926402, and 1926601). 

   more » « less
3. Relationships between sex, body mass and tooth wear in Cayo Santiago rhesus monkeys (Macaca mulatta)

   Guatelli-Steinberg, Debbie; Maldonado, Elizabeth; Kensler, Terry B; Kohn, Luci AP; Zhao, Martin Q; Wang, Q. (January 2021, American journal of physical anthropology)

   null (Ed.)

   Understanding factors affecting tooth wear in primates is of interest because as teeth wear, their chewing efficiency can change—in some species positively and in others negatively. It is well known that teeth wear with age, but relationships between sex and tooth wear and between body size and tooth wear are less well understood. Here we analyze molar wear scores from a cross-sectional sample of 212 Cayo Santiago rhesus monkey (Macaca mulatta) adults examined in 1985. Because males are generally larger than females --potentially processing more food over their lifetimes--we hypothesized that with age included in an ordinal logistic regression model, males would exhibit significantly greater wear than females. We further hypothesized that males of larger body mass would exhibit greater wear than males of smaller body mass. Finally, because many of the females were pregnant or lactating at the time of dental examination, we hypothesized that there would be no relationship between body mass and wear in females. We found that with age included in ordinal logistic regression models, males had significantly more worn molars than females, larger males had more worn molars than smaller males, and that for females, molar wear was not significantly related to body mass. These results suggest that over the life course, animals with larger body sizes (males vs. females and larger vs. smaller males) may accumulate more wear than those with smaller body sizes. Future analyses to be conducted on the Cayo Santiago monkeys’ skeletal remains will further evaluate this possibility. Funding Sources: The Cayo Santiago colony is supported by NIH 5P40OD012217. This project is supported by NSF grants to DG-S., LK., MZ, and QW (NSF #1926528, 1926481, 1926402, and 1926601). 

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4. Dental sculpting and compensatory shearing crests demonstrated in a Wear series of Presbytis rubicunda (Cercopithecoidea, Colobidae) with dental topography analysis

   https://doi.org/10.1002/ajpa.24953  

   Pampush, James D.; Morse, Paul E.; Kay, Richard F. (May 2024, American Journal of Biological Anthropology)

   Abstract ObjectivesMaintaining effective and efficient occlusal morphology presents adaptive challenges for mammals, particularly because mastication produces interactions with foods and other materials that alters the geometry of occlusal surfaces through macrowear and/or catastrophic failure (i.e. “chipping”). Altered occlusal morphologies are often less effective for masticating materials of given diet—but not always—some species exhibit dental sculpting, meaning their dentitions are set up to harness macrowear to hone their occlusal surfaces into more effective morphologies (i.e. secondary morphologies). Here we show that dental sculpting is present in the folivorousPresbytis rubicundaof Borneo. MethodsThirty‐one undamaged lower second molars ofP.rubicundaexhibiting various stages of macroscopic wear were micro‐CT scanned and processed into digital surfaces. The surfaces were measured for convex Dirichlet normal energy (vDNE, a measure of surface sharpness), and degree of surface wear. Regression analyses compared surface sharpness with several measures of wear to test for the presence and magnitude of dental sculpting. ResultsPositive correlations between the wear proxies and vDNE reveal thatP.rubicundawear in such a way as to become sharper, and therefore more effective chewing surfaces by exposing enamel‐dentine junctions on their occlusal surfaces and then honing these junctions into sharpened edges. Compared to another primate folivore in which increasing surface sharpness with macrowear has been demonstrated (i.e.,Alouatta palliata), the worn surfaces are similarly sharp, but the dental sculpting process appears to be different. DiscussionThe results presented here suggest that not only do some primates exhibit dental sculpting and the attendant secondary morphology, but that there appear to be multiple different morphological configurations that can achieve this result.P.rubicundahas thicker enamel and a more stereotyped wear pattern thanA.palliata, although both show positive correlations of occlusal surface sharpness (vDNE) with various wear proxies. These findings shed light on the varied approaches for the maintenance of effective and efficient occlusal surfaces in primates. 

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5. Examining the role of competition in Cercopithecus mitis and Cercopithecus ascanius dietary morphology

   Cicak, Tessa (March 2022, PROGRAM OF THE 91ST ANNUAL MEETING OF THE AMERICAN ASSOCIATION OF BIOLOGICAL ANTHROPOLOGISTS)

   Character displacement, or morphological change in response to competition, is widely documented, but few studies focus on primates. Cercopithecus mitis and Cercopithecus ascanius are typically frugivorous and often associate in multispecies groups, making them good candidates to test the hypothesis that sympatric primates respond to food competition by utilizing alternative resources, resulting in greater differences in molar shape than their allopatric counterparts. Dental impressions were gathered from C. mitis and C. ascanius collected from sympatric sites of Kisangani and Akenge, DRC, and allopatric sites of Kunungu, DRC, and Tana River, Kenya. Sympatric specimens overlapped in time andspace and allopatric samples were chosen with regard to climate and forest structure ensuring adequate comparability between allopatric and sympatric sites. Using micro-CT scans of m1-m3 (n􀀢215), Dental Topographic Analysis variables were extracted using MolaR. Dirichlet Normal Energy, Relief Index, and Orientation Patch Count Rotated were calculated for each tooth position. To quantify the effect of sympatry/allopatry on morphology, a displacement statistic was calculated for each DTA variable at each tooth position. Of the 32 analyses, 19 returned larger sympatric vector values suggestive of competition. While none researched significance, 12 of the analyses had P > 0.5 indicating the pattern is not random. These results are suggestive of competition induced character displacement in C. mitis and C. ascanius. Non-random values were especially common in RFI and DNE vector length results. Higher RFI and DNE scores may indicate higher reliance on fibrous foods at sympatric sites where competition is greater. 

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