ago in Europe, Asia, or both), bones are mostly
silent on the how and the why of this story. By
studying other canids like foxes and wolves,
and by analyzing dog genes, behavior, and
brains—their sweet, friendly, trusting brains—
researchers are developing new ideas about
how the big bad wolf became the dear little dog.
Some argue that their social intelligence is what
makes them extraordinary; others point to their
devotion, that deep soulful craving for humans.
As the first domesticated species, dogs are also a
model for how other mammals—including us— got
that way. Scientists see in their genes and minds
hints about our own unusually tolerant nature.
During much of the human journey from just an-
other primate to world-conquering hominid, our
four-legged pals have been right by our side. They
are our familiar, our echo, our shadow, and as
we now look more closely into their eyes, we can
glimpse a new image of ourselves.ONE NIGHT IN 2011, HECHT AND HER
miniature Australian shepherd, Lefty , were
on the couch watching TV when a show came on
about the legendary Belyaev foxes. Dmitry
Belyaev was a Soviet geneticist in the early
1950s, a time when Moscow suppressed genetic
research as a product of the imperialist West.
Unable to study his chosen field openly, Belyaev
hit upon an ingenious plan. He could experimen-
tally tame foxes raised for their coats. Since
animals kept by humans tend to reproduce
more frequently, officially he’d be accelerating
Soviet fur production. But the project would
sneak in some science. His theory was that justby breeding for tameness, what’s now called
the “domestication syndrome” would emerge:
more-juvenile behavior, and physical changes like
white splotches on the belly and face, floppy ears,
shorter snouts, and smaller teeth.
The research got going in earnest in 1959 in
Siberia. Belyaev’s partners selected animals that
were simultaneously less fearful and less aggres-
sive (these traits typically go hand in hand), then
crossed them. Just four generations later, in 1963,
when collaborator Lyudmila Trut approached
a fox cage, one of the kits wagged its tail at her.
By 1965, a few juveniles were rolling on their
backs and whimpering for attention, just like
puppies. The researchers also kept a population
of randomly bred control animals, and later, a
strain of extremely fearful, combative ones. This
landmark study continues to this day.
Hecht already knew this history. But the show
sparked a realization: Nobody had analyzed the
foxes’ brains. Usually, humans breed goats or
sheep or other domesticated animals for many
traits, including temperament, size, and coat
color, all of which might leave inadvertent marks
on the mind. But differences between tame and
regular fox noggins could be due only to selection98 SPRING 2020 / POPSCI.COM
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