The many origins of intelligence
March 21st 2010 20:13
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By Anthony Doerr
Francis Galton, the Englishman who coined the phrase “nature versus nurture,’’ believed smart people were born smart and dumb people were born dumb. Of course, Galton was also a pioneer of eugenics, the idea that we should selectively breed humans to eliminate our less “desirable” genetic qualities.
In 1904, the statistician Charles Spearman repeated the assertion that general intelligence is fixed and inherent. A person, Spearman insisted, “can be no more trained to have [intelligence] in higher degree than he can be trained to be taller.’’
The idea that we inherit intellectual gifts from our parents is as old as kings and queens. As recently as 1994, Charles Murray and Richard Herrnstein famously wrote in “The Bell Curve’’ about a “cognitive elite,’’ arguing that as “America equalizes the environmental circumstances of people’s lives, the remaining differences in intelligence are increasingly determined by differences in genes.’’
Hmm. Do you agree? Are you good at math? Quick at crossword puzzles? What portion of your own intelligence do you attribute to your DNA? Seventy-five percent? Fifty? Fifteen?
Of course, by even posing that question, I’m subscribing to a fallacy handed down from thinkers like Francis Galton. If it’s not nurture, we assume, then it must be nature. We witness the legacy of that misconstruction everywhere, and not only in the realm of brainpower. Who hasn’t heard an athlete like LeBron James described as “gifted?’’ Who hasn’t heard a singer’s talent described as pure or natural?
In truth, writes journalist David Shenk in a welcome new book called “The Genius in All of Us,’’ “Genes do not, on their own, make us smart, dumb, sassy, polite, depressed, joyful, musical, tone-deaf, athletic, clumsy, literary, or incurious. Those characteristics come from a complex interplay within a dynamic system.’’
What’s that system? Genetics multiplied by environment. No single gene, for example, is in charge of giving a person long arms or killer dance moves or the ability to dunk a basketball. In fact, Shenk argues, genes interact with nutrition, wellness, hormones, culture, the packaging around our DNA, and a vast array of other inputs to create an infinity of possible outcomes.
In other words, the you that is you could have been some entirely different you. For years, Shenk points out, researchers have produced riveting evidence that genes and environment interface dynamically. Yellow grasshoppers can turn black if exposed to charred environments. Fertilized crocodile eggs can become male or female depending on temperature. Put the offspring of rats who test well solving mazes in boring, unstimulating cages and the pups will grow up to be terrible at mazes.
Lately, in the emergent field of epigenetics, we’re even finding that lifestyle in humans might be able to alter heredity.
To read more use the link at top
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