I Think I Can Feel My Brain Evolving
29 May, 2007 07:29 pm
There?s a Far Side cartoon where a kid in a classroom raises his hand and says, ?May I be excused? My brain is full.? After two intense days at a brain evolution symposium, I know just how that feels. The Human Brain Evolving: Papers in Honor of Ralph Holloway just finished up, and my brain quite definitely feels full. (I hope the contents settle and I can cram some more stuff in there soon, though, because I realize how very little I know about brain evolution.)
Bones are obviously important. A number of the presentations described the detailed and careful analysis of particular skulls (or the endocasts made from them, rubber latex shapes made using the skulls as molds) or in one case pelvises (because the size and shape of the pelvis can tell us about the size of the brain at birth). Stones also play a major role; several of the talks discussed the stone tools left behind by our distant ancestors. Interestingly, functional brain imaging can tell us something about how brain evolution is related to the tools that hominids made. Dietrich Stout of University College London described how he, along with Nicholas Toth and Kathy Schick (of Indiana University and the Stone Age Institute), had volunteers make stone tools of the type made during the early Stone Age. (Flint knapping is an interesting activity because of the challenge it presents: using force with accuracy.) They used PET scans, an analysis of the resulting stone tools, and video of the tool-making techniques to learn about the brain areas and cognitive skills involved. They looked at three different activities: Oldowan-style flint knapping before and after a practice period, and an activity described variously as “simple bimanual percussion” and “banging rocks together”. (I liked the slide of someone carefully setting about knapping wearing gloves and goggles.) Stout also talked about how the brain areas involved in tool-making might also be related to the emergence of language.
Well, that was just a small part of the information presented in one paper, but it gives you an idea of the way traditional anthropological activities blend with modern techniques. Jason Kaufman of Caltech described work that he, J. Michael Tyszka, and John Allman did, using a new technique to trace the connectivity of white matter in the brain. He showed some wonderful, detailed images from a gorilla brain, and demonstrated how the technique could be used to map which parts of the corpus callosum (the bridge between the brain’s hemispheres) connect which parts of the brain. James Rilling described work that he and Todd Preuss of Emory did with an imaging technique that allows them to compare human language pathways in the brain with the homologous structures in chimp and macaque brains. I thought all of the brain images were extremely cool.
I thought to myself yesterday that if I were starting college today I’d be tempted to go into the study of brain evolution, but that doesn’t really narrow down a course of study very well. Would I like to do fieldwork to see if I could locate any more of the fossil record, or the follow-up lab work involving painstaking measurement and computer analysis of the resulting finds? Or, to take a completely different tack, how about the type of genetic analysis that I mentioned yesterday, which looked at which genes relating to the brain have changed more in humans than in other species? Or to follow another set of microscopic evidence, what about the study of brain cells to examine things like hemispheric asymmetry in the brain? Comparative brain anatomy of humans and other great apes is also ripe for study (evidently there is a great deal that we don’t yet know; I was also interested and a bit surprised to learn that neurosurgeons are trained using a brain map that was developed 100 years ago based on a single human brain). Well, you get the picture. It’s a complex field. The commentator at the end who spoke briefly about the afternoon’s talks noted the need for some kind of integration of all the different domains that would lead to further testable hypotheses.
Which leads me to the last point I’d like to make (for now) about the symposium. Sometimes people talk of scientists or the scientific approach as being arrogant and too sure of science and its powers. I wish anyone who felt that way could sit and listen to scientists talking about their work, as these scientists did over the last couple of days. I have no doubt that individually scientists can indeed be arrogant, and I’m also sure that the scientific method doesn’t always work perfectly. But the process by which scientists collectively become sure of something is the best we have available for that purpose, and they’re are not shy about saying “I don’t know why it does that” or “I don’t know what that means”, or to point out the areas that still need to be investigated. That latter aspect is probably one of the things that makes science so appealing to so many people. It provides “the joy of finding things out” (as Richard Feynman put it in the title of a book) and the pleasure of having mysteries explained, but it also provides a limitless supply of fresh puzzles and mysteries to try to solve. Much remains to be understood about how our brains evolved, but I consider myself to be one lucky hominid for living in a time when we’re learning so much about how it happened.
Originally posted at The Thinking Meat Project