The Evolutionary Development of the Primate "Brain"
Nadia SCOTT (MPI Leipzig & KLI)
Jun 08, 2017 | 16:30KLI
Organized by: KLI
In an nutshell, soft tissue escapes palaontology. How then can we study the evolution of such structures as the brain across deep time? Albeit with many caveats, the simplest approach is to take the interior of the skull—the endocranium—and to use this as a rough proxy of the brain. By observing how the size and the shape of the endocranium changes across ontogeny, from infancy to adulthood, and by comparing these developmental trajectories across species, we can begin to investigate how species-specific adult morphologies can arise via even very small evolutionary alterations to the so-called tempo and mode of development. According to von Baer, the youngest individuals of closely related species are more likely to resemble one another—low shape disparity—but that evolution acts by modifiying developmental sequences at a later ontogenetic juncture, resulting in high adult shape disparity. To test this using development simulations, we take the infant morphology of one species and apply the average developmental trajectory of another species, and then use classification analyses to assess how closely the simulated adults align with the real adults. Such similarities of development are perhaps indicative of an ancestral mode of development maintained through evolutionary canalization, while differences are attributable to such mechanisms as heterochrony and heterotopy. I will present the results of one study that showed that all greater and lesser apes follow a highly conserved mode of endocranial development. I will also show, using bootstrapping techniques, that we determined for the first time that gorillas and chimpanzees begin with extremely similar morphologies but diverge later in ontogeny through a heterchronic dissociation of size and shape.
Nadia studied biology at the University of Victoria, Canada, where she focussed on comparative chordate anatomy and physiology, while conducting her Honours research in cancer cell signalling. Afterwards, she studied neuroscience at the University of British Columbia for her Master's degree, where she was indebted to a scholarship that allowed her to rotate through three labs and gain hands-on research experience in learning and memory, neurogenesis, genetics and synaptic transmission and plasticity. While at UBC, she was fortunate to collaborate in the area of the ethics of neuroimaging, the results of which were presented at the Presidential Commission for the Study of Bioethical Issues, in Washington, D.C. For her PhD, she sought to combine her twin passions for comparative chordate anatomy and neuroscience by studying the evolution of the primate brain at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, a research institute which seeks to combine comparative genetics, behaviour and anatomy in the study of primate evolution. After a stint at the World Health Organization, Nadia is now wrapping up her thesis at the KLI as a very grateful recipient of a PhD writing-up fellowship. As a keen believer in combining exploration and science, Nadia has conducted multi-year sailing expeditions, been inducted into the Explorers Club, and is currently earning her commercial pilot's licence to further her interests in fieldwork.