“Civilization is a series of techniques in which the hunter-gatherer brain teaches itself to rewire itself. And the sad proof that civilization is a composite of the higher and lower brain functions is seen when civilization breaks down in civil wars, and brutal instincts emerge full-force, and theft, rape destruction, and murder become commonplace. Because the plastic brain can always allow brain functions that it has brought together to separate, a regression to barbarism is always possible, and civilization will always be a tenuous affair that must be taught in each generation and is always, at most, one generation deep.

“When the Brain is Caught Between Two Cultures

“The culturally modified brain is subject to the plastic paradox…, which can make us either more flexible or more rigid — a major problem when changing culture, in a multicultural world.

“Immigration is hard on the plastic brain. The process of learning a culture — acculturation — is an “additive” experience, of learning new things and making new neuronal connections as we “acquire” culture. Additive plasticity occurs when brain change involves growth. But plasticity is also “subtractive” and can involve “taking things away,” as occurs when the adolescent brain prunes away neurons, and when neuronal connections not being used are lost. Each time the plastic brain acquires culture and uses it repeatedly, there is an opportunity cost: the brain loses some neural structure in the process, because plasticity is competitive.

“Patricia Kuhl, of the University of Washington in Seattle, has done brain-wave studies that show that human infants are capable of hearing any sound distinction in all the thousands of languages of our species. But once the critical period of auditory cortex development closes, an infect reared in a single cultural loses the capacity to hear many of those sounds, and unused neutrons are pruned away, until the brain map is dominated by the language of its culture….

“Immigration is usually an unending, brutal workout for the adult brain, requiring a massive rewiring of vast amounts of our cortical real estate. It is a far more difficult matter than simply learning new things, because the new culture is in plastic competition with neural networks that had their critical period of develop in the native land.  Successful assimilation, with few exceptions, requires at least a generation. Only immigrant children who pass through their critical periods in the new culture can hope to find immigration less disorienting and traumatizing. For most, culture shock is brain shock.

“Cultural differences are so persistent because when our native culture is learned and wired into our brains, it becomes “second nature,” seemingly as “natural” as many of the instincts we were born with. The tastes our culture creates — in foods, in type of family, in love, in music — often seem “natural,” even though they may be acquired tastes. The ways we conduct nonverbal communication — how close we stand to other people, the rhythms and volume of our speech, how long we wait before interrupting a conversation — all seem “natural” to us, because they are so deeply wired into our brains. When we change cultures, we are shocked to learn that these customs are not natural at all. Indeed, even when we make a modest change, such as moving to a new house, we discover that something as basic as our sense of space, which seems so natural to us, and numerous routines we were not even aware we had, must slowly be altered while the brain rewires itself.…”

“It has long been assumed that we absorb culture through universally shared, standard-issue, human perceptual equipment, but perceptual learning shows that this assumption is not completely accurate. To a larger degree than we suspected, culture determines what we can and cannot perceive.”

Read The Brain That Changes Itself by Norman Doidge (Viking Penguin, 2007, pages 298-300) to start understanding yourself and others.