James Arthur Lecture on the Evolution of the Human Brain by Katerina Semendeferi
March 4, 2014
The Evolution of Frontal Lobes in Humans and Apes
For more than a century students of human brain evolution identified the frontal lobe as a candidate region of special evolutionary significance given its involvement in complex cognitive functions. Some of these functions include symbolic thought, cognitive planning, decision-making, language production, theory of mind, abstract thinking, planning, and processing emotional stimuli. Unique human cognitive capabilities were thought to result from an overall increase in human brain volume accompanied by a disproportionate increase of the frontal lobe, a dogma that dominated our thinking for the 20th century.
Contemporary research revisited these long held ideas and started testing them with larger samples and new tools. Overall, the relative size of the frontal lobes has not changed significantly during hominid evolution after the split from the last common ancestor with the chimpanzees. While there are clear cognitive differences between humans and apes that involve the frontal lobes, the specific neural underpinnings of these differences are considerably less obvious. How do differences in the size and organization of the hominoid brains produce the cognitive specializations found in our species? Now comparative studies at multiple levels of analysis blend traditional approaches with novel techniques that are applied consistently on both human and ape brains. These research efforts, from genes and molecules to neuronal phenotypes and neural systems, move the field beyond simplistic interpretations based on size alone, and aim to provide a more refined glimpse into the events of the Plio-Pleistocene that gave rise to behaviorally modern humans.
Katerina Semendeferi is Professor in the Department of Anthropology and the Neuroscience Graduate Program at the University of California in San Diego. She completed her training in the fields of Biological Anthropology and Neurosciences and the program in Cognitive Neuroscience at the University of Iowa before joining the faculty at UCSD in 1997. Her research on the evolution of the human brain explores neural systems involved in complex cognitive and emotional processes in humans and apes, as well as in human mental disorders, with a focus on the evolution of the frontal lobes.
Starting in graduate school Semendeferi initiated a project that involved the coordinated effort to collect ape brain specimens from zoos across the U.S. following the natural death of the animals. Another project involved the application of structural Magnetic Resonance Imaging on the collected brain specimens and on living apes. These initiatives introduced noninvasive techniques developed for the analysis of human neural tissue to the comparative study of the hominoid brains and provided material that led to multiple studies published by her laboratory and others in the area of human brain evolution. Semendeferi now works on areas that bridge classic neuroanatomical techniques with state of the art technology at the cellular level.
Semendeferi was elected Fellow of the American Association for the Advancement of Science (AAAS) in 2012 and is the Director of the Laboratory for Human Comparative Neuroanatomy at UCSD.
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September 17, 2014
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September 18, 2014
Charles Darwin’s visit to the Galapagos Islands in 1835 helped him decipher evolution by natural selection, the process responsible for the dizzying abundance of species on the planet.