JUDITH RICH HARRIS
and Developmental Psychologist; Author, The
believe, though I cannot prove it, that three—not
two—selection processes were involved
in human evolution.
first two are familiar: natural selection, which
selects for fitness, and sexual selection, which
selects for sexiness.
third process selects for beauty, but not sexual
beauty—not adult beauty. The ones doing the
selecting weren't potential mates: they were parents.
Parental selection, I call it.
gave me the idea was a passage from a book titled Nisa:
The Life and Words of a !Kung Woman, by the
anthropologist Marjorie Shostak. Nisa was about
fifty years old when she recounted to Shostak,
in remarkable detail, the story of her life as
a member of a hunter-gatherer group.
of the incidents described by Nisa occurred when
she was a child. She had a brother named Kumsa,
about four years younger than herself. When Kumsa
was around three, and still nursing, their mother
realized she was pregnant again. She explained
to Nisa that she was planning to "kill"—that
is, abandon at birth—the new baby, so that
Kumsa could continue to nurse. But when the baby
was born, Nisa's mother had a change of heart. "I
don't want to kill her," she told Nisa. "This little
girl is too beautiful. See how lovely and fair
her skin is?"
of beauty differ in some respects among human societies;
the !Kung are lighter-skinned than most Africans
and perhaps they pride themselves on this feature.
But Nisa's story provides a insight into two practices
that used to be widespread and that I believe played
an important role in human evolution: the abandonment
of newborns that arrived at inopportune times (this
practice has been documented in many human societies
by anthropologists), and the use of aesthetic criteria
to tip the scales in doubtful cases.
with sexual selection, parental selection could
have produced certain kinds of evolutionary changes
very quickly, even if the heartbreaking decision
of whether to rear or abandon a newborn was made
in only a small percentage of births. The characteristics
that could be affected by parental selection would
have to be apparent even in a newborn baby. Two
such characteristics are skin color and hairiness.
selection can help to explain how the Europeans,
who are descended from Africans, developed white
skin over such a short period of time. In Africa,
a cultural preference for light skin (such as Nisa's
mother expressed) would have been counteracted
by other factors that made light skin impractical.
But in less sunny Europe, light skin may actually
have increased fitness, which means that all three
selection processes might have worked together
to produce the rapid change in skin color.
selection coupled with sexual selection can also
account for our hairlessness. In this case, I very
much doubt that fitness played a role; other mammals
of similar size—leopards, lions, zebras,
gazelle, baboons, chimpanzees, and gorillas—get
along fine with fur in Africa, where the change
to hairlessness presumably took place. I believe
(though I cannot prove it) that the transition
to hairlessness took place quickly, over a short
evolutionary time period, and involved only Homo
sapiens or its immediate precursor.
was a cultural thing. Our ancestors thought of
themselves as "people" and thought of fur-bearing
creatures as "animals," just as we do. A baby born
too hairy would have been distinctly less appealing
to its parents.
I am right that the transition to hairlessness
occurred very late in the sequence of evolutionary
changes that led to us, then this can explain two
of the mysteries of paleoanthropology: the survival
of the Neanderthals in Ice Age Europe, and their
disappearance about 30,000 years ago.
believe, though I cannot prove it, that Neanderthals
were covered with a heavy coat of fur, and that
Homo erectus, their ancestor, was as hairy as the
modern chimpanzee. A naked Neanderthal could never
have made it through the Ice Age. Sure, he had
fire, but a blazing hearth couldn't keep him from
freezing when he was out on a hunt. Nor could a
deerskin slung over his shoulders, and there is
no evidence that Neanderthals could sew. They lived
mostly on game, so they had to go out to hunt often,
no matter how rotten the weather. And the game
didn't hang around conveniently close to the entrance
to their cozy cave.
Neanderthals disappeared when Homo sapiens, who
by then had learned the art of sewing, took over
Europe and Asia. This new species, descended from
a southern branch of Homo erectus, was unique among
primates in being hairless. In their view, anything
with fur on it could be classified as "animal"—or,
to put it more bluntly, game. Neanderthal disappeared
in Europe for the same reason the woolly mammoth
disappeared there: the ancestors of the modern
Europeans ate them. In Africa today, hungry humans
eat the meat of chimpanzees and gorillas.
present, I admit, there is insufficient evidence
either to confirm or disconfirm these suppositions.
However, evidence to support my belief in the furriness
of Neanderthals may someday be found. Everything
we currently know about this species comes from
hard stuff like rocks and bones. But softer things,
such as fur, can be preserved in glaciers, and
the glaciers are melting. Someday a hiker may come
across the well-preserved corpse of a furry Neanderthal.