As the title
suggests, Keller argues in this short book that the gene has had its century,
and it is time for biology to focus on broader issues. This is not to say that
genes are not important; Keller is very clear that they are. However, the very
research that has tried to establish exactly what genes do has uncovered
complications, conceptual ambiguities, and non-genetic factors that violate the
simplifying assumptions that came to guide gene research from the middle of the
20^th Century. Contrary to some critical reviews of this book, Keller
is not critical of genetic research in itself; more often, she praises it. She
argues very strongly, however, that genetic research has shown conclusively
that the gene is not what it used to be. Her main point is that the very
success of genetics has (or should) teach us humility. A subsidiary point is
that the rapid changes in genetics have left us with a heritage of inadequate
concepts, specialised practices with little theoretical integration, and a
residue of inadequate but widely accepted ideas of what genes are. Scientists
working in each of these specialised fields know what they are doing, and how
they understand and apply the concepts of genetics, but there is no genetic lingua franca. Unfortunately, given the
social importance of genetics, past and current discourse about genes leaves
the public with the opposite impression. If nothing else, this book is an antidote
to that (possibly dangerous) impression.

The exposition of the
book is historical. The history is a brief synopsis of highlights, and the
triumphs of genetic research are perhaps given less space than many would like,
whereas the problems with the gene concept and with simple views of genetic
determination are emphasised. Given the large number of histories that put the
triumphs of genetic research front and centre, Keller’s emphasis is both
warranted and rather refreshing. The book contains a short introduction and
conclusion, and four longer chapters that are arranged both historically and
thematically.

The first chapter
deals with the regulation of genetic stability. This is the basis for the
functionality of the gene as a unit of heredity. It turns out that the gene is
not stable enough on its own, and needs help. Part of this help comes from
genetically controlled processes, but not all. Still, this leaves the gene as
the central actor in the determination of traits, though it needs its dressers and
perhaps even its directors.

The second chapter
deals with the issue of what genes do. If the gene is a functional unit that
that is responsible for heredity, then it determines heritable traits in the
cell and the whole organism, and can replicate and transmit this capacity for
determination from cell to cell and from organism to organism. Or at least that
was the first version. The discovery of the structure of DNA and the genetic
code confirmed earlier observations that DNA was the locus of inheritance, and
that one gene coded for one enzyme (functional protein). Keller quotes Francis
Crick, “DNA makes RNA, RNA makes proteins, and proteins make us”. Subsequent
discoveries in genetics have shown this to be a bit of an exaggeration. Keller
describes several major modifications in this “Central Dogma”. First, some DNA
regulates other DNA. Second, the RNA transcribed is edited, and many sections
of DNA have multiple mappings onto proteins. If segments of DNA are the units
of heredity, then the units of heredity are not the genes in terms of
developmental function, and vice versa. Sometimes the two coincide, and these
cases are important, but they are far from being the rule. Nonetheless, much
popular opinion, and even much science, works as if the Central Dogma were
Nature’s own Truth.

The next chapter
deals with the concept of a genetic program. This chapter shows how this
somewhat more sophisticated notion of gene activity is supposed to work, and
some of the problems it encounters. The most obvious one is that the way a
program works depends on the type of machine it runs on. It turns out that
there are both surprising similarities across diverse kinds of organism, and
surprising divergences in similar organisms. The idea that the genes are a
blueprint for making an organism is both disarmingly accurate where certain
genes that govern eye development in flies lead to mouse eyes when transplanted
to mice, and dismayingly inaccurate when we look at the genetic details of an
organism as simple as the roundworm, C.
elegans.

Turning to
development, and developmental stability, Keller points to the role of
organisation and redundancy. Both imply no simple relation between genes and
traits. Unlike current computer programs, small variations (and even some large
ones) have little effect on the end result. It is interesting that IBM has
recently started a program to develop systems that have the sort of autonomy
that we see in organisms. Perhaps the program metaphor will become accurate
eventually.

The conclusion is a
rumination on why we still talk of genes, given the problems. Keller suggests
that gene talk is more of a hindrance to the understanding of lay people than
of scientists, since the latter typically know what they are talking about, and
by and large can compensate for inadequacies in gene discourse. Unfortunately,
the “land rush” engendered by genomics has, if anything, led to an even more
unwarranted focus on genes, whatever they are. The advantages of laying claim
to a segment of DNA are too great to allow time to contemplate complicating
details, such as underdetermination or overdetermination of physiological
function. Economic decisions are considerably less corrigible than scientific
ones.

In any case, the
Central Dogma encourages the idea, often reported in the news, of the gene for
X. The problems with the Central Dogma are the problems with the notion of a
gene for X. Science reporters should read Keller’s book carefully, and digest
its message fully. Failing this (and given that with few exceptions reporters
report what they think scientists have said, rather than the science itself, it
will fail), one can hope that people of influence who read those reports will
have read Keller’s book, so they are not so easily swayed by the heroic
archetype of the gene.

© 2002 John Collier

John Collier is a Visiting
Scientist at the Konrad Lorenz Institute for Evolution and Cognition Research. His work is in foundations of information
theory, autonomy, evolutionary theory and theory change, as well as various
papers in metaphysics and the philosophy of physics. He is currently working on
a book on reduction in complex systems with C.A. Hooker.

Categories: Genetics