The authors present extensive but concise descriptions and interpretations
of recent experiments and observations bearing on the influence
on behavior in organisms directed by their genes, as they interact
in combination with each other, and with environments of the organisms.

In the first seven chapters, inferences are made about observed
behavior of various non-human organisms, mainly under laboratory
conditions, which the authors take to be of use in the study of
human behavior, inasmuch as various gene patterns and their chemistry
have been preserved in the course of evolution. The organisms
range from single-celled paramecia to non-human primates. Many
of the usual suspects are reported on, such as round worms, marine
slugs (sea snails), fruit flies, and of course rats and mice.
There is a special chapter on the roles and physiology of pheromones,
chemicals released as signals to be picked up by senses of other
organisms, of the same or different species. Examples are the
much-publicized sexual attractors picked up by smell, although
there are also pheromones which are sexual repellers. Early manifestation
of learning and memory are treated, as in the marine slugs and
fruit flies. There is also a special chapter on biological clocks,
said by the authors to be "one of the most fundamental regulators
in all of biology", and whose study they recommend as "one
of the more fruitful fields of analysis in understanding the genetic
basis of human behavior."

Beginning with Chapter 8, the authors concentrate on genetic effects
on human behavior, with due attention to the role of environments
interacting with genes, and due attention to the fact that single
genes are not often found to be the causes of identifiable human
behaviors. Here, of course, laboratory conditions and techniques
for observations are of a different nature from those available
for many non-human organisms. Again, some of the usual suspects
are exposed, such as inferences made from studies of monozygotic
and dizygotic twins. There is little on inferences one can make
from clinical studies of people with brain or other dysfunctions
of that kind, no doubt because the authors are, respectively,
an immunologist and a biological chemist. However, there are some
references to a few human diseases.

To start with, there is a chapter on genetic control of the activity
of neurotransmitters, chemicals which act as messengers between
body cells. The authors then turn to genetic bases of specific
human behaviors of special interest, as follows: "The Genetics
of Aggression", "The Genetics of Consumption, Part I,
Eating Disorders"; "The Genetics of Consumption, Part
II, Substance Abuse"; "The Genetics of Human Mental
Function"; "The Genetics of Human Sexual Preference"
(especially homosexuality). In each case there are fairly detailed
reports on a variety of comparatively recent researches into the
action of genes on behavior associated with these characteristics.

The last chapter of the book includes a brief examination of the
relative roles of genes and environment in behavior of organisms,
and a brief venture into that great and perennial swamp, problems
of free will and determinism. The authors suggest, without going
into much detail, that chaotic (nonlinear) behavior in the sense
mathematicians introduced the term "chaotic", may provide
an escape from the presumed deterministic actions of genes, on
the one hand, and environmental conditions exterior to organisms,
on the other hand. Their idea seems to be that nonlinear processes
may and often does lead to unpredictable behavior, and that somehow
this is taken by humans, presumably in their becoming conscious
of such behavior (although this is not stated explicitly by the
authors), to have been an action of "free will". This
seems to imply that what humans take to be acts of "free
will" are in fact the result of some sort of illusionary
artifact. The authors suggest that "free will" is not
something we humans can control. They say (p. 269): "…
the very definition of chaotic behavior suggests that it would
operate outside of human consciousness and memory. So if chaos
is a factor in generating human behavior, then it may be that
what we are calling free will is simply a way of accounting for
a certain level of longed-for indeterminacy in our behavior, of
trying to fit it into a pattern that we can understand – and think
we can control." To which I can add that mathematicians,
on the whole, regard chaotic behavior, mathematically speaking,
as describing behavior (e.g., as specified by trajectories of
differential equations) which is deterministic although unpredictable,
in senses if these terms which should be made as mathematically
precise as possible. The authors seem to me to confuse, to some
extent, unpredictability with indeterminism. It’s hard to tell,
though, because they give no definition, to speak of, of the term
"free will", much less that of that term now widely
taboo among scientists of "will" tout court.
Among other things, the authors seem to be dealing with choosing
to do an action, without paying attention to the conscious generation
of choices (if such exists), followed by selection of one or none
or perhaps more than one of these choices, followed by attempts
to carry out the selection, followed by possibly "free"
modifications of the ensuing behavior during interaction of organisms
with their environments (including, of course, other organisms,
which themselves may have "free wills" to some degree).

There are two appendices, one an enlightening one about procedures
used for finding and identifying genes, and relations between
genotypes and phenotypes, and another on that bugaboo of genetic
studies and their applications, the history of eugenics.

© 2002 Gordon Fisher

Gordon Fisher,
Professor Emeritus of Mathematics & Computer Science, one-time
Senior Lecturer in Mathematics & History and Philosophy of
Science.

Categories: Genetics, Philosophical

Tags: Behavioral and Cognitive Sciences, Science (General)