Aping ourselves: Insights on human origins from comparative primate genetics
Anne Stone, Arizona State University
What makes us human? Where did we come from? These are questions that have long engaged us, and the efflorescence of research in human and non-human primate genetics is beginning to provide some answers as well as generate many new questions. Genetic data indicate that our species arose in Africa recently with little to no admixture with archaic populations. As a group, we also have relatively low genetic diversity compared to the “other great apes” despite our extensive cultural diversity. This genetic diversity was shaped by a demographic history pointing to a small population size and even bottlenecks. In such an environment, adaptive changes can spread quickly and leave a signature in our genome. Surprisingly, genomic and expression studies to date have not highlighted large numbers of genes associated with brain function as outliers in terms of significant change in comparisons with other species; however, some genes that are involved in brain size, cognition, and speech, such as FOXP2 and ASPM which were identified by other means, do show dramatic and interesting patterns. Instead, comparative genomic analyses indicate that the greatest changes in our lineage have involved such classes of genes as transcription factors (which regulate other genes), immune function, and metabolism. Within modern humans some of the signatures of adaptive change that are most strongly marked are those that involve immune response to diseases such as malaria, and adaptation to foods such as milk and starch. In this presentation, I use data from the human salivary amylase locus to illustrate an adaptation to high starch diets, as well as data from chimpanzees to help place our evolutionary history in context. Comparative primate genetics is teaching us much about ourselves, both in terms of our population history and our adaptations, and the completion of gorilla and orangutan genomes as well as the Neandertal genome will provide windows into understanding the process of becoming human.
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