Alexandra E. Kralick and Kate McGrath. (2021). More severe stress markersin the teeth of flanged versus unflanged orangutans (Pongo spp.). American Journal of Physical Anthropology. 1:13. DOI: 10.1002/ajpa.24387
McGrath, K., Reid, D.J., Guatelli-Steinberg, D., Arbenz-Smith, K., El Zaatari, S., Fatica, L.M., Kralick, A.E., Cranfield, M.R., Stoinski, T.S., Bromage, T.G. and Mudakikwa, A., 2019. Faster growth corresponds with shallower linear hypoplastic defects in great ape canines. Journal of Human Evolution, 137, p.102691
Open source publication available here
Alexandra E. Kralick and Babette S. Zemel. (2020). Evolutionary perspectives on the developing skeleton and implications for lifelong health. Frontiers in Endocrinology. 11: 99. doi: 10.3389/fendo.2020.00099
Alexandra E. Kralick, M. Loring Burgess, Halszka Golwacka, Keely Arbenz-Smith, Kate McGrath, Christopher B. Ruff, King Chan, Michael R. Cranfield, Tara S. Stoinski, Timothy G. Bromage, Antoine Mudakikwa, Shannon C. McFarlin. (2017). A radiographic study of permanent molar development in wild Virunga mountain gorillas of known chronological age from Rwanda. American Journal of Physical Anthropology. 163(1):129-147.
"Habitat Destruction Is Affecting The Facial Features Of Orangutans"
Frontiers for Young Minds is an open access scientific journal that brings the latest research in real time to school kids
Body Size Variation among Adult Male Orangutans and its Implications for Sexual Dimorphism in Pongo spp.
Orangutans are typically described as exhibiting high sexual dimorphism between males and females, although they also show pronounced within-sex size differences. All males eventually become flanged males, with large cheek pads (flanges) and throat pouches. Most males develop flanges during puberty, but not always. Some males delay the maturation of flanges for anywhere from a few to 20 years. These phenotypically “immature” but reproductively capable males are called adult unflanged males. Orangutan skeletons from wild-shot individuals in museum collections offer a unique opportunity to measure features that correlate with body size, such as long bone length, strength, and bi-iliac breadth. We measured adult orangutan skeletons from museums across the USA and Europe. Our results show that adult unflanged male sizes ranged between those of adult flanged males and adult females. These findings indicate that orangutans are not a sexually dimorphic species per se, and raise intriguing questions about the factors that shape male orangutan phenotypic and sexual maturation in the wild.
Manuscript submitted and in review in Integrative and Comparative Biology, e-mail me for a pre-print or request here
We compared an early life stress indicator, linear enamel hypoplasia (LEH), in the canine teeth of two male orangutan (Pongo spp.) morphs. Flanged males have large bi-discoid cheek pads and a laryngeal throat pouch, and they exhibit either the same or higher levels of the stress hormone cortisol throughout development compared to unflanged males, which lack secondary sexual characteristics. Such ‘developmental arrest’ is hypothesized to either reflect a response to experienced high stress (Hypothesis 1), or an adaptation to avoid elevated stress levels and/or having experienced lower stress levels (Hypothesis 2) during early life. As LEH defect depth has been shown to reflect the severity (i.e., intensity and/or duration) of early life stress events, we examined whether unflanged males have shallower LEH defects than flanged males. Flanged males have significantly deeper LEH defects than unflanged adult males. Canine projected crown heights are similar across males regardless of morph. Evidence from great apes shows that, when comparing canines with similar growth patterns, deeper defects reflect more severe stress events during development. Thus, our results suggest that ‘developmental arrest’ of unflanged males is not a response to having experienced stress, but rather an adaptation to avoid the physiological impacts associated with chronic stress and/or experiencing lower stress levels.
I organized an American Anthropological Association (AAA) invited podium symposium that focused on decolonial theory, contextual reflexivity, and animal ethics in great ape skeletal remains research. The panelists and I developed a manuscript for Evolutionary Anthropology that discusses best practices for improving standards of research on and curation of ape remains. The paper currently in review in Evolutionary Anthropology encourages scholars to consider their own positionality when studying ape remains and provides recommendations for making access to remains more equitable, such as centering and amplifying voices in the Global South in conversations and actions, including digital repatriation and co-ownership of remains. The resulting recommendations include contextualizing the individual, piecing individuals back together, challenging/questioning the captive-wild dichotomy, and collaborative international conversations. This serves as one example of how we can be decolonizing our respective research within biological anthropology.
Relative leg-to-arm strength proportions in Bornean and Sumatran orangutans
Differences in habitat continuity and predators have been posited as explanations for higher rates of terrestrial locomotion in Bornean compared to Sumatran orangutans. However, it is unclear whether greater terrestriality in Bornean orangutans is due to recent environmental changes to their habitats. Orangutan skeletons collected a century ago may shed new light on this question as habitat continuity on both islands would have been greater in the past. In this study, cross-sectional geometry ratios were calculated for orangutans from CT scans. Both orangutan taxa show significantly less relative leg-to- arm strength than all gorillas, even those that climb the most (i.e., western lowland gorillas and infant mountain gorillas). Moreover, Bornean orangutans display limb bone strength proportions that are consistent with more terrestriality than their Sumatran counterparts. Thus, recent habitat discontinuity in Borneo does not explain greater terrestriality in Bornean orangutans, as also suggested by camera trap data, and is most likely due to the absence of tigers on Borneo.
Sarah Caminito's Undergraduate Senior Thesis investigates the oranguans in museum collections who broke and re-healed their long bones using a combination of CT scan methodologies
Principal Instructor of Record
2022, 2021, 2020 ANTH 003 920- Intro Human Evolution, University of Pennsylvania
2022 PSPR 005 920- BioCultural Anthropology of Sex and Gender, University of Pennsylvania
2021 PSPR 023 920- Myths of Human Nature, University of Pennsylvania
2021 Human Osteology, Penn Museum Archaeological Field Skills Bootcamp, University of Pennsylvania
Graduate Teaching Assistant
2018, 2017 ANTH 003- Intro Human Evolution, University of Pennsylvania
2018 ANTH 122- Becoming Human, University of Pennsylvania
2018 ANTH 207- Primate Behavior and Ecology, University of Pennsylvania
K-12 Teaching Experience
2014-2015 High School Science Teacher, Teach for America; Potomac High School, 5211 Boydell Ave, 12, Oxon Hill, Maryland 20745
2015-2016 Education Program Intern, Student Conservation Association; C&O Canal National Historic Park, Great Falls
Undergraduate Research Mentees:
2021-Present Sarah Caminito
2021-Present Clara Nolan
2022-Present Morgan West
2021-Present Jocelyn Salgado
2019-2020 Phoebe Stokes
2019-2020 Anne Lally
Select student media projects created to bust misconceptions!
NSF (National Science Foundation)
The Leakey Foundation
AABA (American Association of Biological Anthropologists)
University of Pennsylvania
George Washington University
© 2022 by Alexandra Kralick
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