Re: What Are the Race Deniers Denying?

Gerold Firl (geroldf@sdd.hp.com)
30 Oct 1996 23:22:19 GMT

Laura - a few weeks ago you posted an excerpt from cavilli-sforza
_history and geography of human genes_ which I found very interesting.
My apologies for the tardy response, but I wonder if you could clarify
what he is trying to say; you wrote:

>You are assuming, rather than demonstrating, the existence of bias.
>Cavalli-Sforza et al. do in fact explain the problems with
>"races" as analytical units for studying human variation. On p.19
>of the book you mention above:

"Human races are still extremely unstable entities in the
hands of modern taxonomists, who define from 3 to 60 or more
races (Garn 1971). To some extent, this latitude depends on
the personal preference of taxonomists, who may choose to be
"lumpers" or "splitters". Although there is no doubt that
there is only one human species, there are clearly no
objective reasons for stopping at any particular level of
taxonomic splitting....

As one goes down the scale of taxonomic hierarchy toward the
lower and lower partitions, the boundaries between clusters
become even less clear. The evolutionary explanation is simple.
There is great genetic variation in all populations, even in
small ones. This individual variation has accumulated over
very long periods, because most polymorphisms observed in
humans antedate the separation into continents, and perhaps
even the origin of the species less than half a million years
ago. The same polymorphisms are found in most populations,
but at different frequencies in each, because the geographic
differentiation of humans is recent, having taken perhaps
one-third or less of the time the species has been in existence.
There has therefore been too little time for the accumulation
of substantial divergence....

From a scientific point of view, the concept of race has failed
to obtain any consensus; none is likely, given the gradual
variation in existence. It may be objected that the racial
stereotypes have a consistency that allows even the layman to
to classify individuals. However, the major stereotypes, all
based on skin color, hair color and form, and facial traits,
reflect superficial differences that are not confirmed by
deeper analysis with more reliable genetic traits.... By means
of painstaking multivariate analysis, we can identify "clusters"
of populations and order them in a hierarchy that we believe
represents the history of fissions in the expansion of the whole
world of anatomically modern humans. *At no level can clusters
be identified with races, since every level of clustering
would determine a different partition and there is no biological
reason to prefer a particular one." (my emphasis)

>This strikes me as a pretty clear explanation.

C-S seems to be saying that we can classify the species into an
arbitrary number of races, depending on what level of clustering we
choose to establish demarcations, and hence race is "unstable". I
guess that's a fair statement, but it shouldn't be interpreted to mean
that race has no basis in biology. The genetic clusters do exist, and
they do correspond to the standard processes of adaptation and drift
which always create geographic variation in any species.

The arbitrary component in this process is how we choose to define our
clusters. Cladistics provides an objective measure of genetic distance
between clusters; we can then choose what level of differentiation our
taxonomy should describe. That doesn't mean that race has no basis in
biology; it's a reflection of the fact that the process of assigning
symbols to describe different aspects of reality *is* somewhat
arbitrary, reflecting our level of interest in communicating and
classifying various components of the universe. In areas that we care
about, our symbols are thickly clustered, with subtle nuances of
meaning reflecting subtle variations in properties. In areas where our
interest is low, we use a coarse-grained one-size-fits-all
terminology. When it comes to humans, our interest is high, hence our
terminology reflects fairly minor differences.

One problem I have with some of the genetic analysis which C-S uses to
examine human variability is the use of characteristics which have
little or no adaptive value, and which predate the evolution of genus
homo. Blood type is easy to measure, and the genetics are simple, but
it's a lousy way to measure human variation. As C-S notes above, most
human polymorphism predates our adaptive radiation. If that variation
has a neutral effect on fitness, then it will reveal nothing about
recent evolution. In non-human species, variation in a single trait
can justify classification as separate subspecies. I see no reason to
apply different standards to the human animal. Perhaps you're concerned
about hurting someones feelings? That someone will feel left-out (or
left-in) because their genetic background either is or is not included
in a particular taxonomic grouping? That's a laudable level of
concern, but scarcely grounds for deciding issues of science. 

-- 

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=-=-=-=-=-=-=-=-=-=-=-=-=-=----   Gerold Firl @ ..hplabs!hp-sdd!geroldf