Research Starter Grant: Investigation of the presumed correspondence between morphological and genetic distance in human populations

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Graciela S. CabanaMinority Postdoctoral Fellowship Starter Grant AbstractThis proposed project is methodological in focus and asks: what is the nature of correspondence, if any, between neutral genetic loci and morphological phenotypic traits? By asking this question, the project's ultimate goal is to re-evaluate assumptions and methods behind assessing population relationships (degree of similarity /dissimilarity) in biological anthropology.Traditionally, bioanthropologists have relied on phenotypic (morphological) trait analyses of the crania to assess population relationships, assuming that a one-to-one correspondence exists between morphological traits and genetic relationships. Although bioanthropologists have always understood that violations of this assumption probably exist, and could potentially impinge on our ability to adequately characterize population relationships, they had access neither to the technology nor the methods to rigorously test this presumed correspondence, until very recently.This proposal takes advantage of the new methodological tools of 3D morphometrics and ancient DNA analyses to test the validity of this fundamental assumption.The proposed project asks two related questions:(1) What is the nature of the relationship between skeletal morphology and genetic distance in modern human populations?(2) Which morphological traits if any, provide the most genetic information?Genetic analyses will be carried out at the Molecular Anthropology laboratories (modern and ancient DNA) at the University of Tennessee, Knoxville (UTK), while morphological analyses will take place at the Bioarchaeology Laboratory at Penn State, headed by Dr. George Milner.Intellectual MeritThe proposed study will investigate the nature of the relationship between human craniodental morphology and genetic distance. It will also address the question of whether genetic distance appears to be the primary determinant of morphological distance, or whether alternative explanations invoking external influences on morphology may be more likely. Finally, the study will identify potential subsets of craniodental data that are most useful in studies of human population relationships, and that can be used in future studies of human population distances.Broader ImpactThe degree of concordance between morphological and genetic data has been a longstanding issue of debate among biologists and geneticists for a wide range of taxa. The extent to which environmental and genetic variables can explain morphology is relevant to research regarding the evolution and anatomy of many different species. Non-congruence between morphology and genetic distances discovered among humans would indicate that the complex relationship of morphology and genetics makes determining genetic relationships from morphology difficult. It would also raise interesting questions about the nature of the interaction of genetics, morphology and the environment to be answered in future studies.