[OPE] Nature/Nurture update: the "dumbing down" effect

Scientists typically use twins to gauge the influence of our genes on the
one hand and the environment on the other. However Turkheimer noticed that
such studies rarely involve twins from broken homes. Stress, neglect and
abuse can have a dramatic effect on intellectual ability. And it's precisely
this factor that many nature-vs.-nurture studies have completely failed to
address.

Turkheimer and his colleagues are the first scientists to have plugged this
gap. Their three studies conducted in the United States on this issue have
now compared the intelligence of hundreds of twins from more privileged
backgrounds with those from more difficult environments. They found that the
higher a child's socioeconomic status, the greater the genetic influence on
the difference in intelligence. The situation is very different for children
from socially disadvantaged families, where differences in intelligence were
hardly inherited at all.

"The IQ of the poorest twins appeared to be almost exclusively determined by
their socioeconomic status," Turkheimer says. A person's intelligence can
only truly blossom if the environment gives the brain what it desires.

Ulman Lindenberger, a 49-year-old psychologist at the Max Planck Institute
for Education Research in Berlin, has come to the same conclusion. He says,
"The proportion of genetic factors in intelligence differences depends on
whether a person's environment enables him to fulfill his genetic
potential." In other words: Seeds that are scattered on infertile soil won't
ever grow into large plants.

This is precisely what intelligence researchers have denied up to now.
Dazzled by their studies of carefree middle-class and upper middle-class
twins, they decided that cognitive skills are largely under genetic control,
that academic talent is biologically hard-wired and can unfurl in almost any
environment.

In the meantime psychologists, neuroscientists, and geneticists have
developed a very different perspective. They now believe that the skill we
term "intelligence" is not in the least fixed, but is actually remarkably
variable. "It is now clear that intelligence is highly modifiable by the
environment," says Richard Nisbett, a psychologist at the University of
Michigan in Ann Arbor.
http://www.spiegel.de/international/zeitgeist/0,1518,716614,00.html

Towards a new kind of environmentalism?

J.

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Received on Mon Sep 13 17:36:45 2010