More Like this

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). 

   more » « less
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). 

   more » « less
4. 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. 

   more » « less
5. Primitive Old World monkey from the earliest Miocene of Kenya and the evolution of cercopithecoid bilophodonty

   https://doi.org/10.1073/pnas.1815423116  

   Rasmussen, D. Tab ; Friscia, Anthony R. ; Gutierrez, Mercedes ; Kappelman, John ; Miller, Ellen R. ; Muteti, Samuel ; Reynoso, Dawn ; Rossie, James B. ; Spell, Terry L. ; Tabor, Neil J. ; et al ( March 2019 , Proceedings of the National Academy of Sciences)

   Old World monkeys (Cercopithecoidea) are a highly successful primate radiation, with more than 130 living species and the broadest geographic range of any extant group except humans. Although cercopithecoids are highly variable in habitat use, social behavior, and diet, a signature dental feature unites all of its extant members: bilophodonty (bi: two, loph: crest, dont: tooth), or the presence of two cross-lophs on the molars. This feature offers an adaptable Bauplan that, with small changes to its individual components, permits its members to process vastly different kinds of food. Old World monkeys diverged from apes perhaps 30 million years ago (Ma) according to molecular estimates, and the molar lophs are sometimes incompletely developed in fossil species, suggesting a mosaic origin for this key adaptation. However, critical aspects of the group’s earliest evolution remain unknown because the cercopithecoid fossil record before ∼18 Ma consists of only two isolated teeth, one from Uganda and one from Tanzania. Here we describe a primitive Old World monkey from Nakwai, Kenya, dated at ∼22 Ma, that offers direct evidence for the initial key steps in the evolution of the cercopithecoid dentition. The simple dentition and absence of bilophodonty in the Nakwai monkey indicate that the initial radiation of Old World monkeys was first characterized by a reorganization of basic molar morphology, and a reliance on cusps rather than lophs suggests frugivorous diets and perhaps hard object feeding. Bilophodonty evolved later, likely in response to the inclusion of leaves in the diet.

    

   more » « less