The Genius in All of Us: New Insights Into Genetics, Talent, and IQ (23 page)

   A single fly’s random genetic mutation can spread into a whole community in a matter of months. Scientists have demonstrated this many times over, breeding gladiator flies, super-memory flies, flightless flies, and so on.

    
“unactualized potential
”:
This term comes from Ceci, Rosenblum, de Bruyn, and Lee, “A Bio-Ecological Model of Intellectual Development,” p. 304.

    
“We have no way of knowing how much unactualized genetic potential exists
”:
Ceci, Rosenblum, de Bruyn, and Lee, “A Bio-Ecological Model of Intellectual Development,” p. xv.

    
This new paradigm does not herald a simple shift from “nature” to “nurture
.
” Instead, it reveals how bankrupt the phrase “nature versus nurture” really is and demands a whole new consideration of how each of us becomes us.

   Among the many scientists calling for this new consideration are Penn State geneticist Gerald E. McClearn. “For most of the past century,” he writes, “the evidence has been clear that a more collaborative model of coaction and interaction of genetic and environmental agencies is more appropriate.” (Gerald E. McClearn, “Nature and nurture,” pp. 124–30.)

As this book was going to press, Mark Blumberg made me aware of a new paper arguing that the phrase “nature versus nurture” should be forever banished.
The citation: Spencer, J. P., M. S. Blumberg, R. McMurray, S. R. Robinson, L. K. Samuelson, and J. B. Tomblin. “Short arms and talking eggs: why we should no longer abide the nativist-empiricist debate.” (
Child Development Perspectives
, July 2009.)

CHAPTER 1:
GENES 2.0—HOW GENES REALLY WORK

PRIMARY SOURCES

My understanding of how genes work and traits develop comes from hundreds of books and articles. The most important (in alphabetical order) are as follows:

Bateson, Patrick, and Paul Martin.
Design for a Life: How Biology and Psychology Shape Human Behavior
. Simon & Schuster, 2001.

Bateson, Patrick, and Matteo Mameli. “The innate and the acquired: useful clusters or a residual distinction from folk biology?”
Developmental Psychobiology
49 (2007): 818–31.

Godfrey-Smith, Peter. “Genes and Codes: Lessons from the Philosophy of Mind?” In
Biology Meets Psychology: Constraints, Conjectures, Connections
, edited by V. Q. Hardcastle. MIT Press, 1999, 305–31.

Gottlieb, Gilbert. “On making behavioral genetics truly developmental.”
Human Development
46 (2003): 337–55.

Griffiths, Paul. “The Fearless Vampire Conservator: Phillip Kitcher and Genetic Determinism.” In
Genes in Development: Rereading the Molecular Paradigm
, edited by E. M. Neumann-Held and C. Rehmann-Sutter. Duke University Press, 2006.

Jablonka, Eva,
and Marion J. Lamb. Evolution in Four Dimensions
. MIT Press, 2005.

Johnston, Timothy D., and Laura Edwards. “Genes, interactions, and the development of behavior.”
Psychological Review
109, no. 1 (2002): 26–34.

McClearn, Gerald E. “Nature and nurture: interaction and coaction.”
American Journal of Medical Genetics
124B, no. 1 (2004): 124–30.

Meaney, Michael J. “Nature, nurture, and the disunity of knowledge.”
Annals of the New York Academy of Sciences
935 (2001): 50–61.

Moore, David S.
The Dependent Gene: The Fallacy of “Nature vs. Nurture.”
Henry Holt, 2003.

Oyama, Susan, Paul E. Griffiths, and Russell D. Gray.
Cycles of Contingency: Developmental Systems and Evolution
. MIT Press, 2003.

Pigliucci, Massimo.
Phenotypic Plasticity: Beyond Nature and Nurture
. Johns Hopkins University Press, 2001.

Ridley, Matt.
Nature via Nurture
. HarperCollins, 2003.

Rutter, Michael, Terrie E. Moffitt, and Avshalom Caspi. “Gene-environment interplay and psychopathology: multiple varieties but real effects.”
Journal of Child Psychology and Psychiatry
47, no. 3/4 (2006): 226–61.

Turkheimer, Eric. “Three laws of behavior genetics and what they mean.”
Current Directions in Psychological Science
9, no. 5 (October 2000): 160–64.

While it would be impossible to further rank the above works in terms of their brilliance or general importance, I must give special credit to Matt Ridley’s
Nature via Nurture
for its importance in laying down a basic new foundation of knowledge of gene-environment interaction. Which does not, of course, mean that Ridley should get blamed for any of my silly mistakes …

CHAPTER NOTES

    
And to think [I’m] the cause of it
:
Chase and Winter, “The Sopranos: Walk Like a Man,” May 6, 2007.

    
The irony is that as America equalizes the [environmental] circumstances
:
Herrnstein and Murray,
The Bell Curve
, p. 91.

   There’s also this gem: “Universal college education cannot be. Most people are not smart enough to profit from an authentic college education.” (Murray and Seligman, “As the Bell Curves.”)

    
“There are no genetic factors that can be studied independently of the environment
.
”

   He uses “phenotype” instead of “a trait.” I substituted so as not to distract the reader. Here’s the original quote: “There are no genetic factors that can be studied independently of the environment, and there are no environmental factors that function independently of the genome. Phenotype emerges only from the interaction of gene and environment.” Meaney continues: “The search for main [direct] effects is a fool’s errand. In the context of modern molecular biology, it is a quest that is without credibility.” (Meaney, “Nature, Nurture, and the Disunity of Knowledge,” pp. 50–61.)

   
We’ve all been taught that we inherit complex traits like intelligence straight from our parents’ DNA in the same way we inherit simple traits like eye color. This belief is continually reinforced by the popular media
.

A few examples:

“An organism’s physiology and behaviour are dictated largely by its genes,” the
Economist
declared in 1999. (Griffiths, “The Fearless Vampire,” p. 4.)

In 2005,
Scientific American
affirmed: “Even such abstract qualities as personality and intelligence are coded for in our genetic blueprint.” (Gazzaniga, “Smarter on Drugs,” p. 32.)

On November 11, 2008, as the writing of this book was drawing to a close, the
New York Times
published a remarkable piece by Carl Zimmer acknowledging a revolutionary new understanding of genes. Some key excerpts:

The familiar double helix of DNA no longer has a monopoly on heredity. Other molecules clinging to DNA can produce striking differences between two organisms with the same genes. And those molecules can be inherited along with DNA … It turns out, for example, that several different proteins may be produced from a single stretch of DNA … It turns out that the genome is also organized in another way, one that brings into question how important genes are in heredity. Our DNA is studded with millions of proteins and other molecules, which determine which genes can produce transcripts and which cannot. New cells inherit those molecules along with DNA. In other words, heredity can flow through a second channel. (Zimmer, “Now: The Rest of the Genome.”)

Still, the online
New York Times
health guide, under the heading “Genetics,” crudely states: “It is common knowledge that a person’s appearance—height, hair color, skin color, and eye color—are determined by genes. Mental abilities and natural talents are also affected by heredity, as is the susceptibility to acquire certain diseases.”

    
Think of your own genetic makeup
:
Friend, “Blueprint for Life,” p. D 01

    
Gregor Mendel demonstrated that basic traits
:
Field Museum, “Gregor Mendel: Planting the Seeds of Genetics.”

    
Mendel had proved the existence of genes—and seemed to prove that genes alone determined the essence of who we are
.
Such was the unequivocal interpretation of early-twentieth-century geneticists.

   Pitzer College’s David S. Moore provides a nice capsule history of genetic determinism from the time of Mendel:

The idea that genetic factors might be able to determine the form of biological and psychological traits has been with us since the beginning of modern theorizing about genes. Although Gregor Mendel did not use the word genes to name the ‘heritable factors’ that he inferred must be responsible for observed variations in his experimental pea plants, the notion of a deterministic ‘germ plasm’ had appeared in several late 19th century writings on biology—most notably in the work of August Weismann—and because of the close conceptual similarity between Mendel’s ‘heritable factors’ and Weismann’s deterministic ‘germ plasm,’ it is little wonder that just a few decades later, Mendel’s factors came to be thought of as deterministic ‘genes.’ T. H. Morgan’s early 20th century discovery that genes are located on chromosomes eventually led to the development of the modern gene theory, which holds that genes are responsible for the development of inherited traits; this conclusion was based on the finding that the presence of particular genetic factors is highly correlated with the presence of particular traits. But even though such correlations do not support the contention that genes operate deterministically, modern gene theory nonetheless retained the genetic determinism that 19th century ‘germ plasm’ theorists relied on to explain the intergenerational transmission of evolutionarily adaptive characteristics. This sort of conceptualization continued to inform theoretical biology well past the middle of the 20th century, as biologists embraced Francois Jacob and Jacques Monod’s operon model of how genes regulate development. (Moore, “Espousing interactions and fielding reactions,” p. 332.)