Evolution’s Rainbow is the first work for a
popular audience by the distinguished Stanford biologist, Joan Roughgarden, and
as such, perhaps marks an auspicious beginning.  The book reads well, and does
an enviable job of covering technical material with facility and grace, not to
mention humor.  But it has a personal edge as well: it is devoted to redressing
our cultural failure to do justice to the diversity of sexual and gender
expression in both the natural and human worlds, and Roughgarden happens to be
a male-to-female transsexual.  Her personal interest and insight are pervasive,
but polemics are strictly kept to a minimum.  Evolution’s Rainbow offers
a serious critical perspective on various theories that tend to minimize,
exclude or pathologize sex and gender diversity.  Suitably, a diversity of
information from the sciences is presented, with many fascinating illustrations
of animal and human forms rarely seen in televised nature programming.

Though
her critique is wide-ranging, Roughgarden’s targets are easily named.   At
broadest, she indicts a number of academic disciplines ranging from biology and
evolutionary science to anthropology and theology, for the suppression of
diversity.  An example of this suppression is the long-standing difficulty in
getting information on animal homosexuality into the academic record.  As she
documents, such information has been ignored or ‘explained away’ to the present
day.  Of course, the charge of discrimination has often been leveled at Western
culture’s concept of sex and gender, and neither this concept nor its critique
are any longer unfamiliar.  But Roughgarden’s case is refreshing in its
particularity and detail.  Conventional assumptions regarding the fixity and
generality of gendered behaviors and roles, of their binate structure, of
mating strategies, and even of body plan of the sexes very quickly begin to
appear naive when faced with examples of fish that change gender and sex in the
course of a life, all-female lizard species that clone themselves yet still
have (lesbian?) sex, bird couples with ‘open’ relationships, primate species
whose members are completely bisexual, and fish whose reproductive strategy
involves the collaboration of three distinct genders.  But such data are
routinely discounted through the assumed normality of a male/female gender
binary.  Much as the cultural projection of normative gender roles tends to
push divergent sexual expression to the margins of the everyday social world,
so has it tended to promote the exclusion of conflicting data in biology, or
the pathologizing of expression in medicine and psychology.  And this must have
consequences, for such omissions invalidate the theorization of sexuality and
gender, for example, in evolutionary theory.  How could one accurately account
for the evolution of sexuality, having left aside the data on same-sex
relations or tri-gendered families?               

Indeed, one of Roughgarden’s specific targets is
the theory of sexual selection.  Darwin imported into evolutionary theory a sex
role binary that seems rather transparently to be more at home in his own
Victorian middle-class world than in the world of his data.  Sexual selection
theory posits as universal (or near universal) a sexually competitive male
bearing outward signs of his possession of good genes (beauty, size, power)
paired with a comparatively passive female who is sexually coy, but discerning
in the interest of acquiring the best possible genes for her offspring.  Ex hypothesi,
the purpose of sex is simply the transfer of sperm between suitable mates. 
This template, which putatively explains differential male and female
appearance, tendencies and patterns of behavior, is treated as a normative
model for sexual reproduction.  But taking shots at nineteenth century theory
may be rather easy, so Roughgarden turns her attention to contemporary sexual
selection theory and finds it little better, introducing into the picture
mistakes even Darwin didn’t make, such as attributing supposedly greater male
promiscuity to the supposed cheaper cost of producing sperm.  A special target
here is evolutionary psychology, lately seen rationalizing rape on empirically
false or theoretically dubious suppositions.

Roughgarden’s complaint against sexual selection
theory is that the diversity in the data tends to disappear behind this
normative binary.  Darwin was aware of considerably greater diversity in the
natural world than his theory seems to allow, yet dismissed it as "rare
exceptions" to the general rule.  By contrast, the detail presented in Evolution’s
Rainbow indicates sexual selection theory is wrong about nearly
everything.  Body plan does not conform to a rigid sex binary: some species do
not have a visible sex distinction, and in species that change sex, sex isn’t
even fixed within a body.  Nor does gender conform to a binary in every case,
and nor does it mean the same thing in every species.  Also, sex roles in
courtship, mating and parenting seem to be reversible.  And this is not even to
mention homosexuality, with which sexual selection theory can scarcely cope at
all.

Roughgarden recommends eliminating sexual
selection from evolutionary theory, and instead proposes her own view, social
selection.  Courtship, she argues, is not about discerning a male’s genetic
quality but rather about determining his likelihood of investing in parental
care for offspring.  Sex is not merely about sperm transfer, but rather about
forming bonds within animal societies and negotiating for access to resources
necessary to reproduce.  Further, the evidence adduced suggests this negotiation
goes on in within-sex relationships as much as in between-sex relationships,
such as in a group of females who share parenting among themselves.  So the
picture of sex that emerges is that mating is about building social
relationships first, and only secondarily about passing on genes.  This
explains why much more sex than reproduction happens, including much non-reproductive
sex, and also allows a clear account of homosexual sex.  The real beauty is
that it does not require an explanation for homosexuality different from that
for heterosexuality: both are about forming social relationships and
negotiating access to resources.  Differences in the prevalence of
homosexuality in different animal societies can be attributed to differences in
the relationships (between-sex, within-sex) which organize and distribute
resources within those societies.  Indeed, the prominent secondary sex
characteristics, which at face value appear to be the basis of mate choice (the
peacock’s tail, the predator’s size), may not be intended for the opposite sex
at all.  Roughgarden introduces the notions of a social-inclusionary trait, the
possession of which gives an animal inclusion within a group and thereby,
access to reproductive opportunities.  An example of this might be the penis of
the female spotted hyena: used to signal in relation to other females, it
enables group membership, without which a hyena may not get the chance to
reproduce.  Roughgarden suggests that social-inclusionary traits may be able to
account for most or all of the traits usually thought of as guiding mate choice
under sexual selection theory.

A couple more of Roughgarden’s targets are worth
mentioning.  Psychology and medicine have had considerable influence in forming
our ideas of normality in behavior and body morphology, and thus in
legitimating differential treatment of those who deviate from the norm. 
Homosexuality, for instance, until recently was listed as a mental disorder in
psychiatry; transexuality still is.  There still remain groups offering to
treat and cure homosexuality.  Children born with atypical genitals (penis too
small, clitoris too large, some of both sexes) are often subjected to
reconstructive surgery to correct their ‘ambiguity’.  Evidently, diversity is
‘not good’ in the eyes of the medical and psychological establishment.  Having
documented some of the disastrous consequences of these procedures, Roughgarden
raises the reasonable question, "who really needs a cure?"  She
challenges some of the dubious bases provided for labeling these traits as
diseases or genetic defects, and concludes that our tendency to pathologize
difference is really what needs to be cured.

To this end, the book closes with some policy
recommendations, ranging from the practical to the symbolic.  Medical and
psychiatric professionals, she suggests, would benefit from being made
familiar, through education, with the true range of diversity.  Such curriculum
change may be regarded as innocent or benign, but more resistance will likely
be provoked by further steps such as FDA regulation of therapy methods and of
the official classification of diseases, apparently a proposal for external
oversight of psychiatry and medicine.  Finally, she suggests a monument to
diversity be erected on the West Coast, to match the Statue of Liberty on the
East Coast.

There is much more in the wealth of detail Evolution’s
Rainbow provides which cannot be adequately covered here.  Most neglected
is the entire third part on diversity in various cultures.  Having examined
diversity in the natural and human worlds in the first two parts of her book, Roughgarden
turns her attention to such sources as the Old Testament, reports of New World
explorers and contemporary Indian culture to reveal the absence of a credible
single norm of behavior.  The message of the book is clear and cogently
reasoned: diversity, whether in the natural or human world, is a good thing and
deserves our respect.

©
2004 George Williamson

George Williamson, Ph.D., Department of
Philosophy, Lakehead University, Thunder Bay, Ontario, Canada

Categories: Philosophical, General