It bears mention at this juncture that the common folk wisdom that brain lateralization has an influence on your personality -- that, for instance, left brain dominant people are sequential, mathematical, and logical, and right brain dominant people are creative, artistic, and holistic -- is complete nonsense. That myth has been around for a long while, and has been roundly debunked, but still persists for some reason.
I first was introduced to the concept of brain dominance when I was in eighth grade. I was having some difficulty reading, and my English teacher, Mrs. Gates, told me she thought I was mixed-brain dominant -- that I didn't have a strongly lateralized brain -- and that this often leads to processing disorders like dyslexia. (She was right, but they still don't know why that connection exists.) It made sense. When I was in kindergarten, I switched back and forth between writing with my right and left hand about five times until my teacher got fed up and told me to simmer down and pick one. I picked my right hand, and have stuck with it ever since, but I still have a lot of lefty characteristics. I tend to pick up a drinking glass with my left hand, and I'm strongly left eye dominant, for example.
Anyhow, Mrs. Gates identified my mixed-brainness, and the outcome apropos of my reading facility, but she also told me that there was one thing that mixed-brain people can learn faster than anyone else. Because of our nearly-equal control from both sides of the brain, we can do a cool thing, which Mrs. Gates taught me and I learned in fifteen seconds flat. I can write, in cursive, forward with my right hand while I'm writing the same thing backwards with my left. (Because it's me, they're both pretty illegible, but it's still kind of a fun party trick.)
[Image licensed under the Creative Commons Evan-Amos, Human-Hands-Front-Back, CC BY-SA 3.0]
Fast forward to today. It's been known for years that lots of animals are lateralized, so it stands to reason that it must confer some kind of evolutionary advantage, but what that might be was unclear until recently.
Research by a team led by Onur Güntürkün, of the Institute of Cognitive Neuroscience at Ruhr-University Bochum, in Germany, has looked at lateralization in animals from cockatoos to zebra fish to humans, and has described the possible evolutionary rationale for having a dominant side of the brain.
"What you do with your hands is a miracle of biological evolution," Güntürkün says. " We are the master of our hands, and by funneling this training to one hemisphere of our brains, we can become more proficient at that kind of dexterity. Natural selection likely provided an advantage that resulted in a proportion of the population -- about 10% -- favoring the opposite hand. The thing that connects the two is parallel processing, which enables us to do two things that use different parts of the brain at the same time."
Additionally, Güntürkün says, our perceptual systems have also evolved that kind of division of labor. Both left and right brain have visual recognition centers, but in humans the one on the right side is more devoted to image recognition, and the one on the left to word and symbol recognition. And this is apparently a very old evolutionary innovation, long predating our use of language; even pigeons have a split perceptual function between the two sides of the brain (and therefore between their eyes). They tend to tilt their heads so their left eye is scanning the ground for food while their right one scans the sky for predators.
So what might seem to be a bad idea -- ceding more control to one side of the brain than the other, making one hand more nimble than the other --turns out to have a distinct advantage. And if you'll indulge me in a little bit of linguistics geekery, for good measure, even our word "dexterous" reflects this phenomenon. "Dexter" is Latin for "right," and reflects the commonness of right-handers, who were considered to be more skillful. (And when you find out that the Latin word for "left" is "sinister," you get a rather unfortunate lens into attitudes toward southpaws.)
Anyhow, there you have it; another interesting feature of our brain physiology explained, and one that has a lot of potential for increasing our understanding of neural development. "Studying asymmetry can provide the most basic blueprints for how the brain is organized," Güntürkün says. "It gives us an unprecedented window into the wiring of the early, developing brain that ultimately determines the fate of the adult brain. Because asymmetry is not limited to human brains, a number of animal models have emerged that can help unravel both the genetic and epigenetic foundations for the phenomenon of lateralization."
I've always been in awe of cryptographers. I love puzzles, but code decipherment has seemed to me to be a little like magic. I've read about such feats as the breaking of the "Enigma" code during World War II by a team led by British computer scientist Alan Turing, and the stunning decipherment of Linear B -- a writing system for which (at first) we knew neither the sound-to-symbol correspondence nor even the language it represented -- by Alice Kober and Michael Ventris.
My reaction each time has been, "I am not nearly smart enough to figure something like this out."
Possibly because it's so unfathomable to me, I've been fascinated with tales of codebreaking ever since I can remember. This is why I was thrilled to read Simon Singh's The Code Book: The Science of Secrecy from Ancient Egypt to Quantum Cryptography, which describes some of the most amazing examples of people's attempts to design codes that were uncrackable -- and the ones who were able to crack them.
If you're at all interested in the science of covert communications, or just like to read about fascinating achievements by incredibly talented people, you definitely need to read The Code Book. Even after I finished it, I still know I'm not smart enough to decipher complex codes, but it sure is fun to read about how others have accomplished it.
[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]
I had a professor of physics in university who used to do the writing trick but with a bit of a twist. He would stretch out his arms and begin writing with his left hand left-to-right and with his right hand right-to-left and they would meet in the middle and the result was a complete sentence. He would then do this over and over until the chalkboard was filled with words, phrases, and equations. Yes, he could do it with complex mathematical equations as well. He claimed to have learned this trick with the sole purpose of making it impossible for his students to keep up while taking notes and force them to pay attention to what he was teaching instead of what was being written down.ReplyDelete