people who have survived trauma.
This swirl of friend-making ecstasy has inspired
a rival origin theory that focuses on feelings
rather than cognition: “their hearts, not their
smarts,” in the words of Clive Wynne, behavioral
scientist at Arizona State University. With col-
laborators Nicole Dorey and Monique Udell at
the University of Florida and Oregon State Uni-
versity, respectively, Wynne proposes that the
essence of dog identity has to do with emotional
connections—love, to use a word rare in science.
“It’s kind of obvious, in a sense,” Wynne says.
“They’re amazingly affectionate. It’s just been
avoided, in part, because it doesn’t sound serious
enough to be a topic of investigation.”
The researchers happened
upon this line of inquiry in
2008, when they set out to es-
tablish further proof for the
“domestication hypothesis.”
But their head- to- head study
of dogs and wolves found
quite the opposite. Well-
socialized wolves from a
research institute in Indiana
easily followed human point-
ing gestures, while some
shelter dogs who’d had little
contact with people did not.
(Later studies showed that
coyotes and even some hand-
reared bats can do it too.)
Another surprise came from a simple test
measuring the amount of time each canid hangs
around a familiar person. Dogs stick close; wolves—
even friendly hand-raised ones—don’t. Dogs, they
reasoned, have a unique drive to bond, even with
members of another species. Every pup is born
with the capacity, including some 750 million stray
“ village dogs” worldwide. Incidentally, that ability to
form interspecies bonds also explains why livestock
breeds can be so vigilant guarding sheep or ducks.
More recently, Princeton University evolution-
ary biologist Bridgett vonHoldt discovered what
might be the root of this affection. In the DNA of
dogs, she and her team found a marker of evolu-
tionary pressure on chromosome 6. In humans,
equivalent mutations cause Williams-Beuren
syndrome, a developmental disorder that leads to
indiscriminate friendliness, or hypersociability. “I
like to think that, in a very positive, adoring fash-
ion, maybe dogs have the canine version of the
syndrome,” she says. Here too the change initially
arose in them, rather than through something we
humans intentionally did.Exactly how a few gene changes could trans-
form a canid or a human into everyone’s BFF is
unclear, and for unknown reasons, the tendency
is stronger in some dogs—cough, Labrador re-
trievers—than others. In one of Hecht’s tests,
known as the “empathy task,” experimenter
McCuistion pretends to smash her thumb with a
hammer, yelping as if in pain. Some animal sub-
jects leap into the person’s lap, licking the faux
wound. Chevy pretty much ignores her.
Nonetheless, studies of different kinds of canines
raised under identical conditions hint that neither
hypersociability nor social-cognition theories like
the “domestication hypothesis” answer every
question. Starting a decade ago, teams at theStockholm University and the University of Vet-
erinary Medicine, Vienna’s Wolf Science Center
began raising groups of dogs and wolves in the lab.
In their first months, both sets of puppies are with
people 24 hours a day; after that, the animals live in
packs with extensive human companionship.
These experiments indicate that dogs aren’t
just wolves with better social skills. For one thing,
hand-raised wolves are quite affable; they happily
greet their caretakers and will go for walks on a
lead. In 2020, the Stockholm team noted, to their
surprise, that a few of their puppies intuitively
comprehend “fetch” gestures, just like dogs do.
In fact, research out of the Wolf Science Center
has found that in some situations, these wild
animals are actually more tolerant than dogs:
Given food to share, dogs keep their distance
from one another. Wolves bicker and snarl at
first, then eat peacefully side by side. In one
study, pairs of wolves or dogs must cooperate to
retrieve a piece of meat; wolves work together
effectively, but dogs were “abysmally bad,” says
investigator Sarah Marshall-Pescini. When sheDOGS HAVE A UNIQUE
DRIVE TO BOND, EVEN
WITH MEMBERS OF
ANOTHER SPECIES.
100 SPRING 2020 / POPSCI.COM