Race and Human Evolution 295At present, we clearly cannot make any assumptions
about intelligence or behavior based on a single pheno-
typic trait such as skin color. Given what we know about
the adaptive significance of human skin color and the fact
that, until 800,000 years ago, the genus Homo exclusively
inhabited the tropics, it is likely that lightly pigmented
skins are a recent development in human history. Darkly
pigmented skins are probably quite ancient. Consistent
with humanity’s African origins, the enzyme tyrosinase,
which converts the amino acid tyrosine into the com-
pound that forms melanin, is present in lightly pigmented
peoples in sufficient quantity to make them very “black.”
The reason it does not is that they have genes that inacti-
vate or inhibit it.^20
Human skin, more liberally endowed with sweat
glands and lacking heavy body hair compared to other
primates, effectively eliminates excess body heat in aThe modern human origins debate hinges on the
question of whether cultural abilities and intelligence
can be inferred from details of skull and skeletal shape
and size. Supporters of the multiregional hypothesis ar-
gue that they cannot.^19 They suggest that using a series
of biological features to represent a type of human being
(Neandertals) with certain cultural capacities (inferior)
is like making assumptions about the cultural capabili-
ties of living humans based on their appearance. In living
people, such assumptions are considered stereotypes or
racism. By arguing that ancient groups like Neandertals
represent a distinct species, supporters of the recent Af-
rican origins hypothesis bypass the potential prejudice
inherent in these assumptions. Both theories embrace
African human origins, and in doing so they confront
the issue of skin color—the physical feature that has ex-
treme political significance today.
Living people today such as this Aborigine do not meet the definition of anatomical modernity proposed in
the recent African origins model. Some paleoanthropologists suggest that this proves that the definition is
problematic because all living people are clearly full-fledged members of the species Homo sapiens.
© Michael Conye/Getty Images(^19) Ibid. (^20) Wills, C. (1994). The skin we’re in. Discover 15 (11), 79.