The tone
of Behavioral Genetics in the Post-Genomic Era is authoritative and
triumphalist. The book weighs in at 636 pages, with 26 articles grouped
together in nine sections. The editors are sure to list their academic
credentials after their names, and have longish biographies in the back
extolling their accomplishments. The spine of the book bears the imprimatur of
the 95,000-member American Psychological Association (APA), and major funding
for the research in the book came from the NIH and Britain’s Wellcome Trust.
The book has three forwards, each by a different luminary in human biology,
including Nobel Laureate James Watson. The content of these forwards lets the
reader know what the editors want to do with all of this scientific authority.
Behavioral geneticist Irving Gottesman calls the book "an advance base
camp in the assault on Mt. Ignorance" and its endorsement by the APA "the
end of a long cold war" (xii). The forward by Watson lets us know who the
enemy in this cold war was, and what the spoils of victory are. By 1975 there
was "incontrovertible evidence for genetic involvement in personality and
intelligence differences" but "those on the radical left continued to
shout ‘not in your genes’" (xxii).  The rhetorical message of the book is
clear: All right thinking people know that genes influence behavior, and we are
here to tell you exactly how they do so. Any opposition to us is motivated by
politics, not science.

      The
message is powerful in part because all right thinking people do know that
genes influence behavior. Consensus has it that human psychological traits
arise out of the interaction of genes and the environment. The authority here
is being used to push more than the interactionism that everyone agrees on and
that the evidence indicates. The editors’ agenda has two levels. First, they
allow only a very narrow conception of how genes can interact with the
environment, one that winds up giving genes the dominant role. This conception
is far from scientific orthodoxy, and likely to be false. Their agenda is also
manifest in the sorts of behavioral traits they discuss. Three whole chapters
of the book are devoted to the albatross of human behavioral genetics: Spearman’s
g, representing general cognitive ability. It is clearly a very
important part of the agenda of this book that humans can be ranked by
intelligence using a single number, and that this number represents a strongly
heritable trait. Although the editors never make any remarks about race, their
emphasis on general cognitive ability allies them with the racist
pseudo-science of Cyril Burt, Arthur Jenson, and Richard Herrnstein and Charles
Murray. This is the more narrow political agenda that has led to the cold war
mentioned in Gottesman’s forward. There is actually a lot of useful information
in Behavioral Genetics. Libraries would be wise to stock it, researchers
and clinicians wise to consult it. Readers should be aware, though, that this
is not a definitive statement of the state of a maturing science. It is another
salvo in a war that has been going on in psychology since the 19th century, and
despite their rhetoric, the editors of Behavioral Genetics are not on
the winning side of this war.

      The narrow
agenda of Behavioral Genetics is established by the framework of the
book: introductory and concluding chapters by the editors, and a set of five
chapters under the heading "Research Strategies" following the
introduction. The focus of these chapters is on a single program for
understanding the genesis of complex traits, the search for quantitative trait
loci (QTL). Broadly, QTL are the locations on the chromosome for any gene that
makes a small contribution to a trait that can be measured quantitatively. The
assumption in Behavioral Genetics is largely that QTL will be
individually Mendelian, but always interact in a simple additive fashion to
create a nice bell curve distribution of the trait in the population. This
assumption is often true in plant and animal breeding, but it is incredibly
unlikely to be true of complex traits like those of human psychology. Indeed
one of the few breaks from the triumphalism of the book is the repeated
admission that "progress to date in identifying QTLs has been slower than
expected" (534). Many explanations are given of this fact. In the
introduction and conclusion, the editors stress the need to break the "1%
barrier": the reason we have been unable to find QTL is that we have only
been able to identify genes with large effects. If we can find genes that
account for 1% or less of the existing variance, we can begin to detect QTL.
Chapter 4, part of the "Research Strategies" section, suggests that
QTL have not been found because standards of proof have been too high: an
excessive concern with false positives has led us to miss true findings (56).
The possibility that QTL have not been found for human behavior because
psychological traits are generally not the product of the additive interaction
of genes is not taken seriously. The volume does contain a review of nonadditive
forms of gene H gene interaction
(called epistasis), which even admits that almost all complex traits will be
the product of nonadditive interaction, but it is for some reason not included
in the section on research methods. Instead it is in the cognitive disabilities
section, between chapters on Attention Deficit Hyperactivity Disorder (ADHD)
and autism. The complications introduced by epistasis for the search for QTL
are not addressed in any of the chapters promoting such a search. There are
other problems, in addition to the neglect of epistasis. The focus of the book
is on the 40,000 or so genes that code for proteins and their regulatory
sequences. The roles of genes that code for RNA only and of epigenetic
inheritance are neglected. On the whole, this book is misnamed. At a minimum it
should be called Quantitative Behavioral Genetics in the Postgenomic Era.
It would even more accurately be called Quantitative Behavioral Genetics,
Using a Very Narrow Understanding of "Quantitative", in the Postgenomic
Era.

      Why the
focus on a single method? The three chapters on general cognitive ability,
including one by the lead editor, Robert Plomin, seem to give answer. Since the
19th century beginnings of the modern era of research on human genetics, there
has been an effort to identify a single factor, labeled g, that explains
all significant variation in human cognitive ability, can be measured by IQ
tests, and which is strongly heritable. For much of its history, this research
has had openly racist aims, as documented thoroughly in books like Steven Jay
Gould’s classic The Mismeasure of Man. The usefulness of these
ideas for racists is obvious. Once you have all of the premises about g
I named above, one need only add the often-true premise that a minority group
tends to perform badly on IQ tests, to get a cogent argument for the genetic
inferiority of the group in question. Fortunately the first premise behind this
argument is simply false: there is no reason to think that human cognitive
ability reduces to a single factor. Arguments for the other two premises—that
this factor is measured by IQ tests and is strongly heritable—are also often
dubious, but the point is moot anyway, because the factor in question simply
doesn’t exist. The chapters on general cognitive ability, however, assume all
of these premises. Plomin’s chapter, in particular, is festooned with citations
to Arthur Jenson and other major figures in the tradition of racist IQ testing.
Plomin basically takes as his central question, "what are the QTL that
underlie g?" In doing this he assumes three- fourths of a racist
argument, asserting all the discredited premises, and leaving out only the
premise about performance on IQ tests, the one premise that mentions race and
is in fact sometimes true. This creepy style of argument casts a pall over the
whole book.

      General
cognitive ability is not the only psychological trait covered in this book,
although it is the most extensively covered. There are two chapters each on
addiction, ADHD, and depression. Single chapters are devoted to speech and
language, reading disorders, autism, schizophrenia, dementia, anxiety, and
personality. Most of these are well-defined traits, like autism or
schizophrenia, with inheritance patterns that clearly indicate a genetic
component. These chapters contain reviews of the current research, outlines of
the most successful techniques, and suggestions for the direction of future
investigation. These chapters also seem to focus less intently on the desire to
simply identify QTL. They form the bulk of the book and provide a good reason
for libraries to stock it. A detailed evaluation of any of these chapters,
though, would have to be written by a specialist in the relevant disorder, which
is beyond my capacities.

      Given the
technical detail of this book, the target audience is clearly researchers and
clinicians. Patients and their families, and academics who are not full-time
researchers in genetics, can find useful information here but may have to work
to dig it out. The glossary is missing many useful terms (e.g. nonparametric
linkage analysis) and includes many unneeded ones (e.g. "nucleotide"
and "half-sibling"). The real problem with this book is that someone
looking for information on the genetics of autism might walk away misled about
research on genes and intelligence, and on the direction of research into gene H environment interaction.

©
2004 Robert Loftis

J. Robert Loftis,
Ph.D., Visiting Assistant Professor, Department of Philosophy, St. Lawrence
University, New York.

Categories: Psychology, Philosophical