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The Science in
"The Hand You're Dealt"
by Robert J. Sawyer
Copyright © 1998 by Robert J. Sawyer
All Rights Reserved
Do not read this essay until after
you have read the short story
"The Hand You're Dealt."
I hope you enjoyed "The Hand You're Dealt." Here are some
notes on the science that went into making the story,
for those who are curious about such things.
For speculation on the role of genetics
in shaping the fine details of personality, see Living
with Our Genes by Dean Hamer, a molecular biologist with
the U.S. National Institutes of Health, and Peter Copeland
Two good journal articles on this topic are listed below:
"Our Genes, Ourselves?" by Ari Berkowitz, from the January 1996
issue of BioScience. Abstract:
Genetic research supports that genes determine the physical,
behavioral, emotional and cognitive characteristics of humans.
Although these aspects are also controlled by biological
mechanisms, linkage studies show that genes determine
peoples' abilities, preferences and emotions.
"Genetic dissection of complex traits" by Eric S. Lander and
Nicholas J. Schork from the September 30, 1994, issue of
Medical genetics was revolutionized during the 1980s by the
application of genetic mapping to locate the genes responsible
for simple Mendelian diseases. Most diseases and traits,
however, do not follow simple inheritance patterns. Geneticists
have thus begun taking up the even greater challenge of the
genetic dissection of complex traits. Four major approaches have
been developed: linkage analysis, allele-sharing methods,
association studies, and polygenic analysis of experimental
crosses. This article synthesizes the current state of the
genetic dissection of complex traits describing the methods,
limitations, and recent applications to biological problems.
For briefer, popular treatments of the same themes, see:
- "The Personality Genes: Does DNA Shape Behavior?" by J. Madeline Nash
in the April 27, 1998, issue of Time, and
- "Were You Born That Way?" by Karen Kuehn, George Howe Colt, and Anne
Hollister in the April 1998 issue of Life.
Dean Hamer (author of the first book I cited above) is the
most interesting figure in the study of genes that influence complex
behaviors. He has already, he believes, identified genes and gene
combinations associated with such things as:
- having difficulty quitting smoking
- novelty-seeking (or thrill-seeking) behavior, such as skydiving
- male homosexuality
How, you might ask, could genes control such behaviors? Well, on
a biochemical basis, the thrill-seeking gene seems to produce a
protein that is less efficient at absorbing dopamine, the
neurotransmitter that makes us feel good after intense
experiences; if you have trouble absorbing it, then you need much
more intense experiences to get that same thrill and,
voilà! suddenly you're jumping out of a plane in hopes
of stimulating that feeling.
Anxiety likewise has a chemical basis, based on serotonin levels
in the brain.
But what about male homosexuality? Because it was the most
controversial of Hamer's finds, it got the most press. The
research by Hamer and his colleagues points to a stretch of DNA
called Xq28 at the tip of the X chromosome; its presence or
absence correlates very strongly with whether a man declares
himself to be gay. The original study makes fascinating reading:
"A linkage between DNA markers on the X chromosome and male
sexual orientation," by Dean H. Hamer, Stella Hu, Victoria A.
Magnuson, Nan Hu, and Angela M. L. Pattatucci (Science,
July 1993). For supporting evidence from a later follow-up
study, see "X chromosome again linked to homosexuality" by
John Travis (Science News, November 4, 1995).
And what about future extrapolations? As we complete the
sequencing of all the DNA that makes up a human being (the goal
of the current international Human Genome Project), and we start
setting present and future supercomputers to the task of finding
correlations between observable human behaviors and specific
genetic markers, will we find genes or gene combinations that are
indicative of other complex behaviors? It's quite reasonable to
suppose the answer is yes. Among those I mention in
"The Hand You're Dealt" are genes for group
sex with Asian women and for incestuous pedophilia.
Although I confess to at least partially choosing the initial
example for its humor value, it is something that's much
more likely to have a genetic basis than, say, liking being
whipped specifically with chains. Why? Because the male
tendency to want to scatter sperm far and wide clearly is genetic
(the more women one impregnates, the more
copies of one's genes get to live); a group-sex gene is just a
more-aggressive version of what is essentially the male-adultery
gene being predisposed to not just maximizing sexual partners
over a lifetime, but maximizing them in each sexual encounter.
What about the desire for Asian women? Well, first, of
course, being a North American, I'm using the term "Asian" in the
North American sense of meaning racially Oriental, not the
European sense of someone from Asia; no North American refers to
a native of India as an Asian, but Europeans commonly do; North
Americans use "Asian" because "Oriental" is not currently
considered politically correct.
Anyway, a gene for a desire for Asian women is much more
plausible than one for a desire for, say, Catholic women, since
ethnicity is entirely genetic, whereas religion is, for most
people, a matter of personal choice. But a desire in a white man
(the character in my story with this gene has the last name
Korsakov; he's presumably descended from Russian stock) for women
who, at a glance, are very different from him genetically is
nothing more than a refinement of that old male tendency to want
to scatter genetic material far and wide. The genes are, in
essence, saying: "that women looks nothing like the body
currently carrying me, and therefore can't have yet integrated
much of my DNA into her gene pool."
And since both the "group sex" concept and the "women who aren't
part of my gene pool already" concept are both driven by the same
goal maximizing dissemination of genetic material it's
quite reasonable to propose a gene that links them both.
What about the gene for incest? Well, although concentrating
recessive genetic disorders is clearly not in your gene's best
interest if the offspring dies before it can reproduce, incest
does afford an opportunity to produce offspring with 75%, instead
of the normal 50%, of your own genetic material; clearly there
would be some "selfish gene" (to use
phrase) selection pressure in favor of a genetic basis for it.
More Good Reading
The story "The Hand You're Dealt"
"The Hand You're Dealt" nominated for the Hugo Award
"The Hand You're Dealt" nominated for the Arthur Ellis Award
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