A POSITIVE CONCLUSION 353
Homo sapiens—would then have faced all the moral dilemmas
involved in treating a human species of disdnctly inferior mental
capacity. What would we have done with them—slavery? extirpa-
tion? coexistence? menial labor? reservations? zoos?
Similarly, our own species, Homo sapiens, might have included a
set of subspecies (races) with meaningfully different genetic capaci-
ties. If our species were millions of years old (many are), and if its
races had been geographically separated for most of this time with-
out significant genetic interchange, then large genetic differences
might have slowly accumulated between groups. But Homo sapiens
is, at most, a few hundred thousand years old, and all modern hu-
man races probably split from a common ancestral stock only about
a hundred thousand years ago. A few outstanding traits of external
appearance lead to our subjective judgment of important differ-
ences. But biologists have recently affirmed—as long suspected—
that the overall genetic differences among human races are aston-
ishingly small. Although frequencies for different states of a gene
differ among races, we have found no "race genes"—that is, states
fixed in certain races and absent from all others. Lewontin (1972)
studied variation in seventeen genes coding for differences in blood
and found that only 6.3 percent of the variation can be attributed to
racial membership. Fully 85.4 percent of the variation occurred
within local populations (the remaining 8.3 percent records differ-
ences among local populations within a race). As Lewontin re-
marked (personal communication): if the holocaust comes and a
small tribe deep in the New Guinea forests are the only survivors,
almost all the genetic variation now expressed among the innumera-
ble groups of our five billion people will be preserved.
This information about limited genetic differences among
human groups is useful as well as interesting, often in the deepest
sense—for saving lives. When American eugenicists attributed dis-
eases of poverty to the inferior genetic construction of poor people,
they could propose no systematic remedy other than sterilization.
When Joseph Goldberger proved that pellagra was not a genetic
disorder, but a result of vitamin deficiency among the poor, he
could cure it.