arguments that favor the hereditability of intelligence:
arguments that favor the cultivation of intelligence
The most strenuous efforts to raise the IQ's of slow
learners must surely have been made... to no avail. We can't bring the
mildly retarded up to the level of average intelligence, much less to a
Experimental intervention programs have had minimal
or no success. The Milwaukee Project produced no lasting boosts in IQ.
The Abecedarian program raised IQ's an average of 5 points 10 years later.
However, it might be argued that these programs might not be as effective
as stimulating home environments coupled with a love of learning and mental
exercise. Also, these programs didn't last throughout childhood. Still,
considered opinion must have been that these programs weren't worth what
People like my friend Jerry, who didn't know the brainy
side of his family, has nevertheless shown startling intelligence from
early childhood to this day.
V, who was adopted immediately after birth, picked out
letters on billboards at 9 months, and was reading in full by 15 months,
to the amazement and consternation of his foster-parents. Having heard
stories about prodigies coming to bad ends, his foster-parents made no
effort to encourage his phenomenal precocity. Clearly, this would argue
in favor of a dominant role for heredity in determining intelligence.
At the top of this list has to be the Flynn Effect.
Overall IQ scores have risen about 25 points since the 1916 Stanford Binet
Test was first published in 1916. Virtually none of this rise has taken
place in vocabulary, arithmetic, or general knowledge, with scores doubling
in non-verbal areas. It's worth noting that vocabulary may not be as accessible
as it was in 1920, with reading on the wane, and television, movies and
video games doing little to expand one's vocabulary Similarly, arithmetic
is performed by pocket calculators and cash registers, reducing the need
for arithmetic proficiency that have characterized earlier decades. However,
one would think that general knowledge wouldn't be subject to these reductions
in exposure. But be that as it may, the Flynn Effect has been a rising
tide that lifts all boats throughout the industrialized world, and has
raised African-American scores at the same rate it has raised the scores
of other ethnic groups. And this must be environmental. Natural selection
in humans has been working to lower our IQ's over time, as the less-intelligent
out-bred the more intelligent. Sir Francis Galton was appalled at the way
lower-class English families were birthing far more children than the none
or one or two that upper-class families were producing. (This may not be
the case anymore, since birth rates in industrialized nations have declined
at all levels of socio-economic status.) It's estimated that, in industrialized
nations, this has led to drop of 5 points of IQ over the past 200 years.
While such prodigies as John Stuart Mill, Norbert Wiener and William Sidis
sprang from brilliant parents, it's hard to avoid the conclusion that they
wouldn't have been the super-prodigies they were without the early stimulation
and cockering they got from their parents. It wouldn't be terribly surprising
if it turned out that early mental stimulation challenges juvenile brains
to wire themselves for higher levels of mental capability.
Another factor in this process could be that those who are relatively bright
get positive reinforcement, and tend toward self-stimulation, whereas those
who don't perceive themselves as exceptionally seek other trellises along
which to grow. (This is Dr. Flynn's suggested mechanism for the differentiation
The lifetime exercise of mental faculties, and especially, of problem-solving,
might produce long-term
changes in the brain that take decades to fully evolve.
about the Flynn Effect
Testing of older British civil servants and corporate
employees by John Raven in 1948, coupled with follow-up tests administered
by Dr. Raven's son in 1992, has shown that Raven Test subjects born in
1877 who scored at or above the 90th percentile on the Raven Progressive
Matrices Test matched the performances of individuals born in 1967
who scored in the 5th percentile! Now the 5th percentile represents a Raven-derived
IQ of 75, while the 90th percentile indicates a Raven-derived IQ of 121.
Someone born in 1877 with a Raven-derived IQ of 121 would fall at the 5th
percentile (IQ = 79) if they had taken the Raven test in 1992! To say it
another way, someone born in 1877 would have a Raven-derived IQ of 65 today,
while someone born in 1967, if they could travel back in time to 1902,
would have a Raven-derived IQ of 153. (I'm emphasizing "Raven-derived"
because the cohort born in 1877 would had vocabularies, arithmetic capabilities
and general information close to those of today's citizenry.)
The point is that the environmental changes attributable
to the Flynn Effect are huge, and do represent an elevation of those with
IQ's of 65 to an average level of 100 with respect to those pattern recognition
aptitudes which the Raven Test measures.
My guess is that there is a hereditary component
to human intelligence, but that environmental influences, when they involve
"total immersion", can produce very large effects in cognitive powers.
learned to read before he was three, and Sarah
Sidis observed of her son, William
Sidis, that, "Before he was two he would go gravely to the book case
and pick out any book that a visitor asked for. This so amused and pleased
them, that he soon took pleasure in opening the books and reading from
them to his father and guests, and by the time he was three he read well.")