About

W. Scott McGraw is an evolutionary anatomist and primate behavioralist with primary research interests in Africa. He is a professor and chair in the Department of Anthropology at The Ohio State University. Dr. McGraw's work involves studying primate behavior and evolution, with a focus on Africa, and he has contributed to science and conservation efforts in African rainforests. His research supports anti-poaching patrols, wildlife education programs in rural African schools, and exchange programs for African and OSU students. Dr. McGraw's expertise and research are documented in his CV, and he is actively involved in various research laboratories within the department.

Research topics

• Biology
• Ecology
• Dentistry
• Microbiology
• Genetics
• Zoology
• Medicine
• Demography
• Virology
• Botany
• Evolutionary biology

Selected publications

• Enamel Prism Angle Variation and Hard‐Object Feeding in Cercopithecoids With Known Diets

  American Journal of Biological Anthropology · 2025-11-01 · 1 citations

  articleOpen access

  OBJECTIVES: To examine relationships between enamel prism angles relative to wear surfaces and dietary hardness in three cercopithecoid genera. We hypothesized that the hard-object feeding (durophagous) Cercocebus atys and Lophocebus albigena would have higher prism angles, making their enamel in this region stiffer and stronger in this region, than the soft-object feeding Cercopithecus. We further investigated whether the habitually durophagous Cercocebus atys and the fallback hard-object feeding Lophocebus albigena had similarly high prism angles. MATERIALS AND METHODS: Molars were sectioned using standard protocols and imaged with a Motic BA 310 Microscope with a Moticam camera. ImageJ FIJI was used to measure prism and wear angles. Measurements were made on 13 Cercocebus atys, 13 Lophocebus albigena, and 11 Cercopithecus molars, though sample sizes varied for different comparisons. RESULTS: Repeated measures regressions of upper functional and non-functional cusps were used to test for the effects of tooth, genus, tooth-genus interaction, and wear angle on prism angle. Genus and wear angle were found to be statistically significant predictors. Pairwise comparisons revealed significantly higher prism angles in Cercocebus atys vs. both Lophocebus albigena and Cercopithecus. There was no significant difference between Lophocebus albigena and Cercopithecus in prism angles. DISCUSSION: Our finding that the prism angles of a fallback hard-object feeder (Lophocebus albigena) are more similar to those of a soft-object feeder (Cercopithecus) than to a habitual hard-object feeder (Cercocebus atys) suggests that the correspondence between durophagy and enamel microstructure is not straightforward, complicating our ability to infer durophagy in the fossil record.

  PublisherOA PDFDOI

• Investigating relationships among strontium, barium, and seasonality in wild baboons

  Archaeometry · 2025-08-06 · 1 citations

  articleOpen access

  Abstract Geochemical profiles of Australopithecus africanus and baboon teeth show fluctuating trace elements, possibly reflecting seasonal diets. Here we use laser ablation–inductively coupled plasma–mass spectrometric measurements of calcium‐normalized strontium and barium ratios (Sr/Ca and Ba/Ca) and ion microprobe analyses of oxygen isotopes (δ 18 O) to contrast elemental changes with seasonal rainfall in wild baboons. We employ 16 teeth from 11 South African, Ethiopian, and Ugandan individuals. Changes in Sr/Ca and Ba/Ca ratios are not consistently linked to wet or dry seasons. Additional studies are needed to identify sources of Sr and Ba, and what such patterns can tell us about seasonal behaviour.

  PublisherOA PDFDOI

• Chewing performance and the structure of primate communities

  Universität Zürich, ZORA · 2025-12-17

  articleOpen accessSenior author

  Ecomorphological theory predicts a relationship between the morphology of a given trait and its ecological performance. In turn, variation in ecomorphology is viewed as integral to the structuring of animal communities. This reasoning is practically axiomatic, but the full logic chain is seldom integrated into a single study. We tested the functional relationship between premolar tooth size and chewing performance across a diverse community of wild primates, including chimpanzees and seven monkey species. We found that relatively large premolars were associated with improved food fracture, and that the chewing performance of granivores (seed predators) exceeded that of sympatric folivores and frugivores by 51–56% and 64–68%, respectively. This finding is robust when controlling for variation in chewing effort and seasonal grit ingestion. Evidence of convergent evolution speaks to the fitness advantages of enlarged premolars among granivorous species, and we show that premolar-mediated seed-eating shapes the composition of primate communities across nine African forest sites. Our findings are relevant to palaeoanthropology and the puzzling megadontia of some fossil hominin lineages, as our data favour a diet of stress-limited brittle foods, not ductile foods, as the principal selective pressure favouring the performance benefits of enlarged premolars.

  PublisherDOI

• Postural behavior of wild aye-ayes in Madagascar’s Ihofa Forest

  Folia Primatologica · 2025-02-19

  articleSenior author

  We studied an adult female and a juvenile male aye-aye (Daubentonia madagascariensis) in Madagascar's Ihofa forest from May to December 2017 to investigate whether the postural diversity of this lemur varied with age, maintenance activity, and habitat use. We used bout sampling (female N = 488, male N = 355) to record postures during feeding and resting and tested for differences using χ 2 . For both individuals, bimanual and unimanual cling were the most common postures used during feeding (78.4% and 82.9%) and these behaviors were strongly associated with the use of vertical supports - trunks and bamboo - in the main canopy. When feeding on branches and boughs, pronograde postures such as tri-pedal crouch and crouch were most common. Most rest occurred on horizontal branches using primarily pronograde postures. Our data indicate that although aye-ayes exploit multiple forest strata, the great majority of feeding is accomplished using orthograde postures from vertical supports, even in forest strata dominated by horizontal supports. These findings support recent arguments about the significance of vertically oriented behaviors in the evolution of early mammalian arboreal quadrupeds.

  PublisherDOI

• Chewing performance and the structure of primate communities

  Proceedings of the Royal Society B Biological Sciences · 2025-12-17

  articleOpen accessSenior author

  Ecomorphological theory predicts a relationship between the morphology of a given trait and its ecological performance. In turn, variation in ecomorphology is viewed as integral to the structuring of animal communities. This reasoning is practically axiomatic, but the full logic chain is seldom integrated into a single study. We tested the functional relationship between premolar tooth size and chewing performance across a diverse community of wild primates, including chimpanzees and seven monkey species. We found that relatively large premolars were associated with improved food fracture, and that the chewing performance of granivores (seed predators) exceeded that of sympatric folivores and frugivores by 51-56% and 64-68%, respectively. This finding is robust when controlling for variation in chewing effort and seasonal grit ingestion. Evidence of convergent evolution speaks to the fitness advantages of enlarged premolars among granivorous species, and we show that premolar-mediated seed-eating shapes the composition of primate communities across nine African forest sites. Our findings are relevant to palaeoanthropology and the puzzling megadontia of some fossil hominin lineages, as our data favour a diet of stress-limited brittle foods, not ductile foods, as the principal selective pressure favouring the performance benefits of enlarged premolars.

  PublisherOA PDFDOI

• Evolutionary History of the Endangered Sanje Mangabey (Cercocebus sanjei) in the Udzungwa Mountains, Tanzania: Inferences from Phylogeography and Historical Niche Modelling

  Primates · 2025-09-16

  preprintOpen access

  Understanding whether a species' distribution results from recent and/or anthropogenic events or ancient vicariant factors is critical for conservation planning. The Endangered Sanje mangabey (Cercocebus sanjei), endemic to Tanzania's Udzungwa Mountains, is currently divided into two populations located approximately 100 km apart. These represent distinct evolutionary lineages that diverged around 0.77 million years ago (MYA). We aimed to investigate i) the phylogeographic history and recent changes in size and range of the two Sanje mangabey populations, and ii) whether lack of suitable habitat between populations and consequent difficulty to disperse may have influenced the 0.77 MYA divergence time. We used 64 mitochondrial control region sequences obtained from non-invasive DNA. The probability of suitable habitat across Tanzania and the Udzungwa Mountains was modelled at three time points: Mid-Holocene (6,000 YA), Last Glacial Maximum (22,000 YA), and the Last Interglacial period (120,000-140,000 YA). We found six haplotypes, clustered into two haplogroups. Significant differentiation was estimated between populations, which show no evidence for recent range expansion or contraction. The ecological niche modelling revealed fluctuating extents of suitable habitat across southern Tanzania. Large genetic differentiation between populations may have been influenced by a general trend in aridification in East Africa across the last 40,000 years, resulting in a shift of montane forests to gradually higher elevations. Intermediate populations may have become extinct as suitable habitat retracted, leaving relict populations with relatively stable demographic histories ancestral to the present-day populations. This study supports their preliminary designation as separate evolutionary significant units, a conclusion with conservation management implications.

  PublisherDOI

• Inter‐Observer Processing and Measurement Error Are Low for <scp>2D</scp> Dental Measurements on Shared <scp>microCT</scp> Scans

  American Journal of Biological Anthropology · 2025-01-31

  articleOpen access

  OBJECTIVES: Sharing micro-computed tomographic (μCT) scans of teeth increases data accessibility and reduces the need for repeated scans of any given specimen. However, the use of the same TIFF stacks or DICOMs by multiple individuals has the potential to introduce new sources of error. Here, we explore whether use of the same μCT scans by different persons produces comparable results. MATERIALS AND METHODS: Worn (N = 11) and unworn (N = 4) Cercocebus atys upper molars (UM1 N = 8, UM2 N = 7) were μCT scanned using a Bruker Skyscan 1172 High Resolution Ex Vivo Scanner at a resolution of 22 μm. Two individuals (K.N.G. and M.C.O.) created a 2D mesial slice for each TIFF stack (tooth). Worn teeth were reconstructed by K.N.G. and M.C.O. Three researchers (M.C.O., K.N.G., and J.R.) measured tooth shape, linear enamel thickness, average enamel thickness, and relative enamel thickness (AET and RET). Inter-observer percent error was calculated for each measurement. Univariate ANOVAs were calculated to evaluate variance due to slice maker, reconstructor, tooth, and measurer when percent error averaged > 5%. RESULTS: For unworn teeth, error was generally low and largely due to the person doing the measurement. For worn teeth, wear reconstructor was a statistically significant source of variation for AET and RET. DISCUSSION: We found that (1) inter-observer error was generally low, (2) linear measurements are prone to error, (3) worn teeth did not present an additional source of error as compared to unworn teeth, and (4) different people can use the same μCT scans to reliably reconstruct, slice, and measure teeth.

  PublisherOA PDFDOI

• On the phylogenetic history of the Sanje mangabey (Cercocebus sanjei)

  Research Square · 2024-11-21 · 1 citations

  preprintOpen access
  PublisherOA PDFDOI

• To conserve African tropical forests, invest in the protection of its most endangered group of monkeys, red colobus

  Conservation Letters · 2024-04-30 · 11 citations

  articleOpen access

  Abstract Forest loss and overhunting are eroding African tropical biodiversity and threatening local human food security, livelihoods, and health. Emblematic of this ecological crisis is Africa's most endangered group of monkeys, the red colobus (genus Piliocolobus ). All 17 species, found in forests from Senegal in the west to the Zanzibar archipelago in the east, are threatened with extinction. Red colobus are among the most vulnerable mammals to gun hunting, typically disappearing from heavily hunted forests before most other large‐bodied animals. Despite their conservation status, they are rarely a focus of conservation attention and continue to be understudied. However, red colobus can act as critical barometers of forest health and serve as flagships for catalyzing broader African tropical forest conservation efforts. We offer a plan for conservation of red colobus and their habitats and discuss conservation and policy implications.

  PublisherOA PDFDOI

• Tropical field stations yield high conservation return on investment

  UNC Libraries · 2024-10-16

  articleOpen access

  Conservation funding is currently limited; cost‐effective conservation solutions are essential. We suggest that the thousands of field stations worldwide can play key roles at the frontline of biodiversity conservation and have high intrinsic value. We assessed field stations’ conservation return on investment and explored the impact of COVID‐19. We surveyed leaders of field stations across tropical regions that host primate research; 157 field stations in 56 countries responded. Respondents reported improved habitat quality and reduced hunting rates at over 80% of field stations and lower operational costs per km 2 than protected areas, yet half of those surveyed have less funding now than in 2019. Spatial analyses support field station presence as reducing deforestation. These “earth observatories” provide a high return on investment; we advocate for increased support of field station programs and for governments to support their vital conservation efforts by investing accordingly.

  PublisherDOI

Frequent coauthors

• David J. Daegling

  University of Florida

  58 shared

• Sery Gonedelé Bi

  Swiss Centre for Scientific Research

  18 shared

• Eloi Anderson Bitty

  Université Félix Houphouët-Boigny

  17 shared

• Erin E. Kane

  Boston University

  16 shared

• Debbie Guatelli‐Steinberg

  The Ohio State University

  15 shared

• John G. Fleagle

  Stony Brook University

  13 shared

• Klaus Zuberbühler

  University of Neuchâtel

  13 shared

• Fiona Maisels

  Wildlife Conservation Society

  11 shared