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Wolves To Dogs
Defenders Magazine, Fall 2007
- From Wolves To Dogs
Scientists work
to solve the puzzles of the origin of "man's best friend"
by Jim Yuskavitch
 How
did a wild, wary and intelligent predator turn into one of
humankind’s most beloved companions?
One conventional story begins in Europe many millennia ago, with
a band of Stone Age nomads gathered around their campfire as the
primeval forest grows dark around them. The women roast mammoth
meat over the flames while the men knap stone spear points,
preparing for the next day’s hunt. At the edge of the campfire’s
flickering glow, children play with a small creature—a wolf
puppy the clan picked up on its travels, perhaps stumbling upon
an orphan or stealing it from a den. That wolf pup will be tamed
and eventually bred with other human-adopted wolves—out of which
will arise the domestic dogs we know today.
There is little doubt that
man’s best friend—Canis familiaris, in the scientific
parlance—descends from wolves, and it was likely the first
animal to be domesticated. But much else about this conventional
story of the origin of dogs has been thrown into doubt. In
recent years, researchers using techniques ranging from DNA
analysis to behavioral investigations have uncovered evidence
that potentially paints a much different picture of when, where
and how dogs first became an integral part of the human
experience.
The idea that some kind of
“wolf dog” may have been a companion to Stone Age peoples is
derived from discoveries of 100,000-year-old canid bones and
skulls at a European archaeological site. These finds hinted
dogs may have diverged from wolves by that time and might have
been domesticated as well. Some genetic research in the 1990s
supported the notion that dogs split from wolves as far back as
135,000 years ago.
But until recently the evidence
seemed stronger that domestic dogs originated not in Europe, but
in the Middle East, and long after the Stone Age—perhaps 10,000
to 15,000 years ago. This belief was based on dog bones found
together with human remains from that time and place, and
because so many other things—both plant and animal—were tamed in
that part of the world, demonstrating its inhabitants had the
requisite knowledge for such endeavors.
Both of these theories about
domestic dogs’ beginnings were challenged in 2002, when Peter
Savolainen, a molecular biologist with the Royal Institute of
Technology in Stockholm, Sweden, and his colleagues published
the results of their research on dog DNA.
Savolainen’s interest in the
evolution of dogs began in 1992 when he worked with Sweden’s
National Laboratory of Forensic Science. There he analyzed dog
hairs found at the scenes of two high-profile murders—hairs that
investigators hoped would lead to the dog’s owner and the
killer. Although his work did not solve the crime, it led him to
begin looking at the heredity of domestic dog breeds through a
DNA analysis of dog hairs he collected from local dog shows. “We
expected to see different DNA types within each breed,” says
Savolainen. “But we found the same type in all the breeds,
whether it was a German shepherd or a poodle.”
That suggested a common
ancestor for the domestic dog, and Savolainen set out to find
where that first dog came from. “I sat down and thought it would
be possible to study dog hair DNA,” he continues. “All you would
need was a sample from all the dog populations of the world. I
was optimistic and stupid enough to think that I could do it.”
 DNA,
or deoxyribonucleic acid, is a complex molecule that is the
basic building block of genetic inheritance. Savolainen and
colleagues focused on mitochondrial DNA, which is passed down
from the mother to offspring, and is involved in supplying
energy to cells. By looking at the genetic variability exhibited
by a living organism, scientists can determine its lineage.
Greater genetic variability indicates an older origin.
In 1998 Savolainen began
contacting colleagues, dog organizations and others, asking them
to send him a few hairs from their dogs. He was able to collect
and examine 1,000 hair samples from 654 types of dogs from
around the world, a task that took three years.
“We found more DNA types in
hair samples from East Asian dogs and that larger variability
suggests that domestic dogs originated in East Asia,” Savolainen
says.
This suggestion, if true, would
place the origin of dogs several thousand miles farther east
than many experts previously thought, and it would trace their
source gene pool to a few female Asian wolves.
Savolainen speculates that the
difference in size between Asian and European wolves may have
had something to do with the East Asian origin of the dog. Since
wolves from this part of the world are smaller than their
European and northern Asian counterparts, they may have been
easier for humans to handle, he says. Middle Eastern wolves are
also smaller and figure similarly in the hypothesis of dog
domestication in that region.
Savolainen and his colleagues
were also able to project a probable time for the origin of
domestic dogs, basing it on the known mutation rate over time of
their genetic samples. That date—15,000 years ago—is consistent
with the earliest known archaeological evidence of domestic dogs
in association with humans.
If Savolainen’s findings hold
up to scrutiny, they imply that domestic dogs spread throughout
the world from East Asia by trade or migrated with
people—including to the Americas. That view is bolstered by a
genetic study of New World dogs conducted by researchers at
Sweden’s Uppsala University around the same time as Savolainen’s
study. These researchers found that dogs in the Americas are
genetically virtually identical to Old World dogs. That
indicates Native Americans did not domesticate their dogs from
local wolves. Instead, their forebears brought the animals with
them when they crossed the Bering land bridge at least 12,000
years ago.
But what was the process that
transformed wild wolf to dog? How would some wolves that
competed with humans for food and risked death from our
ancestors’ spears or clubs, cross over to the human camp?
Raymond Coppinger, a biologist who recently retired from
Hampshire College in Massachusetts, has studied the behavior of
dogs and wolves for decades and believes he knows the answer to
those questions.
His idea is that wild wolves
domesticated themselves. “I describe domestication as being able
to eat in the presence of human beings,” says Coppinger. His
hypothesis may seem dubious until you take a closer look at the
period in Earth’s history when domestication was commonly
thought to have occurred, and the kind of human societies that
existed at that time.
Coppinger dismisses the idea
that people living more than 10,000 years ago could have had the
time, inclination or expertise to domesticate wolves. Based on
his own and his graduate students’ work with wolves, Coppinger
believes that to have any chance at all of “socializing” a wolf,
a pup needs to be taken from its parents by the time it is 19
days old. According to Coppinger, if you try to socialize a wolf
to humans later than that, the process never really takes—and it
will always remain a wild, and potentially dangerous, animal.
The fact that a 19-day-old wolf
would need to be bottle-fed formula is only one of the problems
our Stone Age tribe would have encountered trying to raise its
wolf pup. These people, like the wild animals they hunted, were
in a constant struggle for survival. “Hunter-gatherer societies
were not time-surplus societies,” says Coppinger. “They were not
like us. There is no way they could isolate and breed domestic
dogs from wolves. And they’re a bugger to train.”
Instead, Coppinger believes the
domestication process—initiated by the wolves themselves—began
around 10,000 years ago as humans incorporated agriculture into
their societies and established permanent or semi-permanent
settlements. Wolves started visiting village garbage dumps to
glean discarded food scraps. Although dump food was of poor
quality, it was a steady and reliable source that some wolves
would have found an acceptable trade-off over the dangers and
rigors of catching wild prey.
At first the scavenging wolves
probably ran off when humans approached, returning later when
they thought it was safe. Some wolves, too frightened by the
experience, never came back. But over time the wolves that stuck
around became increasingly used to the presence of people and
their “flight distance”—the distance at which a potential danger
causes an animal to run off—narrowed, perhaps to the point that
they just moved aside a bit when humans came to dump trash.
Every now and then one of the braver villagers may have reached
out and offered a morsel of food from his hand and it was warily
accepted by one of the more trusting wolves, accelerating the
socialization process.
Eventually, this tolerance for
humans in close proximity would have been bred into successive
generations of “trash-dump wolves” until the animals made the
transition to living among the villagers and relying on them
completely for food, shelter and protection, Coppinger argues.
“A dog is a wild animal that can eat in the presence of human
beings,” he says.
Coppinger believes the domestic
dog was ubiquitous in human societies by 7,000 to 8,000 years
ago, noting that dog remains, including some wearing collars,
are found in abundance at archeological sites from that period
and after.
The questions about wolves and
dogs are far from settled—some scientists disagree with
Savolainen and Coppinger’s conclusions, and there is always more
to investigate. Savolainen has recently completed genetic
research on dingos in Australia—considered to be one of the
“ancient” dog lines—and found that they were, as believed,
established on that continent by humans about 5,000 years ago
from just a handful of founding animals. He is continuing his
genetic work on East Asian dogs and is especially interested in
pinpointing more precisely where dogs arose and how they spread
to the rest of the world. Coppinger, who says that Canis
lupus and Canis familiaris have such an intimately
entwined genealogy that they are virtually one and the same
animal, is skeptical an exact location for the origin of
domestic dogs can ever be ascertained.
It seems incongruous that the
beginnings of an animal we know so well can remain a mystery for
so long. From early theories based on archeological guesswork to
the more recent use of DNA analysis, researchers will continue
their scientific inquiries into the origin of the domestic dog.
But wherever those studies may lead, dogs will always remain our
faithful companions and direct links to their—and our—wild
pasts.
Oregon-based freelance writer Jim Yuskavitch specializes in
fish, wildlife and environmental issues. The Globe Pequot Press
will publish his sixth book,
Fishing Washington, in 2008. (More on Jim
Yuskavitch
HERE)
Defending Wolves
We may never unravel all of the mysteries of the wolf’s
evolution into the dog, but one thing is certain: Wild wolves
are imperiled in many places today and need our help.
In the northern Rockies, for example, wolves have made a
dramatic comeback in the past decade thanks to the federal
Endangered Species Act. But some state officials in this region
are threatening to persecute wolves again if federal protections
end. Idaho’s governor “Butch” Otter says that he wants the first
tag to kill a wolf and that Idaho will seek to kill hundreds of
its wolves when they are removed from the endangered species
list. Likewise, Wyoming plans to strip all protection for wolves
across 90 percent of the state immediately upon delisting,
allowing all wolves in this enormous “dead zone” to be killed on
sight.
"Until all the states in the region commit to science-based
conservation management of wolves, federal protections for
wolves should remain in place,” says Suzanne Stone, Defenders’
northern Rockies representative.
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