Alexandra Kralick is currently a Postdoctoral Fellow in Gender and Science at the Harvard University GenderSci lab.
As an anthropologist trained in a four-field approach, she pushes disciplinary boundaries by engaging with queer theory to examine the ways in which skeletons defy normative expectations of biological sex and gender.
She recently graduated with her Ph.D. from the University of Pennsylvania Department of Anthropology where her dissertation examined life history and functional morphology of sex differences in the orangutan skeleton. She focused on two types of male orangutans, flanged and unflanged, and developed an osteobiographic approach identify the morphology and maturation of flanging status in museum collections. Her work engaged with contextual reflexivity, decolonial theory, and discussions of ethics and equity in great ape skeletal remains research.
She earned her B.S. in Biological Anthropology from The George Washington University in 2014 where she studied gorilla dental development and wrist bone shape.
Alexandra E. Kralick, Stephanie Canington, Andrea Eller, and Kate McGrath.Specimens as Individuals: Four interventions and recommendations for great ape skeletal collections research and curation. (2023) Evolutionary Anthropology.1:20. doi: 10.1002/evan.22002
Beyond Dimorphism: Body Size Variation among Adult Orangutans is not Dichotomous by Sex
Alexandra E Kralick, Caitlin A O'Connell, Meredith L Bastian, Morgan K Hoke, Babette S Zemel, Theodore G Schurr, Matthew W Tocheri. (2023). Beyond Dimorphism: Body Size Variation among Adult Orangutans is not Dichotomous by Sex, Integrative and Comparative Biology, icad015, https://doi.org/10.1093/icb/icad015
Sex and Biology: Broader Impacts Beyond the Binary
Sam Sharpe, Andrew P.Anderson, Idelle Cooper, Alexandra E. Kralick, Timothy James, HansLindahl, Sara Lipshutz, J. F. McLaughlin, Banu Subramaniam, Alicia Roth Weigel,A. Kelsey Lewis. Sex and Biology: Broader Impacts Beyond the Binary. Integrative and Comparative Biology. 1:8. doi: 10.1093/icb/icad113
More severe stress markers in the teeth of flanged versus unflanged orangutans (Pongo spp.)
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
Faster growth corresponds with shallower linear hypoplastic defects in great ape canines
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
Evolutionary perspectives on the developing skeleton and implications for lifelong health
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
A radiographic study of permanent molar development in wild Virunga mountain gorillas of known chronological age from Rwanda
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.
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.
Defects in Flanged and Unflanged Male Orangutan Canine Teeth
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.
Lost Lives of Orangutans: Restoring Identities to Great Apes in Museum Collections Research
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 out 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 orangutans by species and sex
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.
Evidence of orangutans compensating for broken and re-healed arm bones using other limbs
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
3D analysis of gorilla wrist shape
African apes are all primarily terrestrial knuckle-walkers but western lowland gorillas (Gorilla gorilla gorilla) climb more frequently than do eastern gorillas (Gorilla beringei), a consequence of ecological differences in their respective habitats. Although bonobos (Pan paniscus) have generally been assumed to be more arboreal than common chimpanzees (Pan troglodytes), recent fieldwork suggests this is not true. We tested whether western lowland gorillas, being relatively more arboreal, exhibit trapezium morphology that enhances pollical grasping ability in comparison to eastern gorillas, whereas trapezoid morphology should vary less among gorillas given its functional role in weight support during knuckle-walking. In contrast, common chimpanzees and bonobos should be more similar to one another in terms of both trapezium and trapezoid morphology. Using 3D geometric morphometrics, our results follow some of the expected predictions in that western lowland gorilla trapezia are distinguishable from those of eastern gorillas in ways that are reasonably attributable to pollical grasping. Overall, these results underscore the challenges of identifying functionally relevant shape variation in hominoid carpal bones while also highlighting a large amount of unexpected carpal shape variation within African ape taxa that is probably best explained by genetic drift.