Thirty karrots on the pinky, kiss the ring on the Don
Humans are asymmetric animals. Early in our embryonic development, the heart turns to the left. The liver develops on the right. The left and right lungs have distinct structure. (…)
When it comes to handedness, another basic human asymmetry, which reflects the structure and function of the brain, the reversed pattern is relatively common, and for all that, not easily understood. (…)
The riddle of what underlies handedness remains. Its proportions — roughly 90 percent of people are right-handed and 10 percent left-handed — stay consistent over time.
Hand dominance (whether left or right) is related to brain asymmetry. And that, Dr. Francks said, “is not at all understood; we’re really at the very beginning of understanding what makes the brain asymmetrical.”
Though brain asymmetries exist in our closest primate relatives, there seems to be general consensus that the human brain is more profoundly asymmetric, and that understanding that asymmetry will show us much about who we are and how our brains work.
