 IT'S NOT OFTEN
that a registered breed of dog starts with a castoff that even
the pound didn't want and a stray plucked out of the woods.
But it is even less likely that such animals would provide one
of those rare "Eureka!" moments in science, drawing
back the curtain on both evolution and human culture, and providing
clues to the mysterious origins of the long, fruitful partnership
that exists between humans and canines.
And yet, that's exactly what happened
with the shy enigma of a creature known as the Carolina dog,
which just may be a remnant of the first animals to accompany
humans across the Bering land bridge to North America thousands
of years ago. Then again, it may be nothing more than a
modern mutt; no one is exactly sure, and the genetic evidence,
while suggestive, is thus far inconclusive. Regardless,
the Carolina dog, and several other demonstrably primitive canids,
some nearing extinction, are part of a controversial reexamination
of how modern dogs arose, and even more fundamental questions
about the process of domestication itself.
If you passed a Carolina dog on a back
road in humid South Carolina Low Country, where stands of tall
longleaf pine alternate with crop fields and cypress swamps,
chances are you wouldn't spare it a glance — it would seem
to be just a scrawny, medium-sized mongrel with a reddish-yellow
coat, upright ears and a whiplash tail curling up over its back,
what rural Southerners have long called a "yaller"
dog. And for years, that's all I. Lehr Brisbin, Jr., thought
they were, too
Brisbin — "Bris"
to his colleagues at the Savannah River Ecology Lab (SREL) in
Aiken, South Carolina — saw these skittish feral dogs from
time to time. Brisbin is a senior ecologist on the sprawling
Savannah River Site, a huge nuclear reservation carved  out
of the local farmland in the 1950s by the federal government,
which built reactors there for the defense program. The
reactors are shut down now, and the Savannah site — 310
square miles of mostly forest and wetlands — is a National
Environmental Research Park. Fenced off with barbed wire
and closed to the public, it is a fertile haven for wildlife
despite some areas with residual radioactivity.
Brisbin,
a trim man in his late 50s with bottomless energy, is a polymath
with professional interests that range from alligators and box
turtles to wood storks and furbearers. His graduate work
on the bioenergetics of reptiles and birds first led him to study
red junglefowl, the ancestors of modern chickens. And that
sparked a curiosity about the process of domestication in animals,
which in turn meshed neatly with his lifelong passion for dogs
and dog training.
And that
led him, eventually, to Horace and Marion.
Horace was a stray, white with
brown markings, found wandering in the late '70s on the boundary
of the Savannah River Site. There wasn't anything terribly
special about him — he seemed just a typical rural mutt
of the sort you'd find chained to back porches and doghouses
from the Carolinas to Texas. Brisbin, whose specialty at
the time was training American Staffordshire terriers and bloodhounds,
added Horace to his kennel of show dogs, and for several years
didn't spare him much more thought.
Which
is a little odd, because Brisbin was beginning to think about
feral dogs. Early in his research on domestication, he
became fascinated by the origins of truly wild dogs, like the
dingo in Australia, a honey-gold dog believed to have come to
the island continent with humans about 4,000 years ago.
He wondered whether the dogs that came to North America
with humans might have been similar to dingoes, and he studied
the archaeological and anthropological evidence. And he spent
his spare time learning about the so-called pariah dogs of the
Old World, which share traits with dingoes.
In many
corners of Europe, Asia and Africa, on the margins of human civilization,
there are dogs lurking in the shadows — not pampered house
pets, but untamed, often malnourished animals scavenging for
scraps and garbage, avoiding people, surviving on the edge between
wild and tame. Regardless of the setting — Afghanistan,
Korea, Malaysia, the Papua New Guinea highlands — they frequently
share common attributes: shorthaired coats that may be multi-colored
but are often ginger, curled tails, erect ears and foxlike faces.
In India these animals are called pariahs, after the low-ranking
social caste, and that name has come to be applied to such populations
elsewhere. In fact,
Brisbin has defined a "pariah
niche," a pervasive canine lifestyle that revolves around
scavenging garbage near human settlements.
One winter day several years after
Horace arrived, Brisbin had him out for a run with his other,
pedigreed dogs. That day, for some reason, Brisbin looked
beyond Horace's piebald coat to his shape and proportions, and
it struck him that the dog looked just like a dingo, like the
pariahs halfway around the world. "At that moment
everything just fell into place," he says now, 20 years
later.
Brisbin realized
 that he'd been seeing dogs that looked like dingoes
for years, roaming the woods of the Savannah River Site, often
turning up in the traps he'd set as part of his regular furbearer
surveys. On a hunch, he drove that day to an animal shelter
just to see if they had more of these dingo-like dogs. Sitting
in a kennel, with only her head poking out of a box, was a dog
that looked like she had stepped out of the Australian outback.
The shelter operators thought Brisbin
was crazy for taking the untamed animal, but they were also glad
to find a home for such a thoroughly unadoptable dog. "So
they go into the doghouse with a noose pole and drag her
out screaming, spread-eagled, leaving claw marks through the
kennel, and put her, urinating all over herself, into this cage
in the back of my car. And I was handed a card, which I
have to this day." Bris shakes his head and laughs.
"It's got this little dog face, and it says, 'We are pleased
you found room in your heart and your home to adopt this
"Little One"' — who was yelping in my cage, shaking
like a leaf — 'who comes fully guaranteed to love, protect
and be loyal to you as long as it lives.' "
"And you know, ironically,
she has", he says. Brisbin named the dog Marion, after
Gen. Francis Marion, the "Swamp Fox" of the Revolutionary
War. And while she has never become his "little one,"
she did learn to accept and tolerate him, the same way an aloof
cat tolerates its owner, respectful but always distant, preserving
her space and dignity.
Today,
Marion is a 14-year-old matriarch, her coat somewhat threadbare,
her muzzle gray and her eyes cloudy, her gait stiff and arthritic.
But she retains some of the wildness that marked her early life;
even around Brisbin she is shy and at a remove. A visitor
who sits for a long time, pretending that he has no interest
in her, may receive a careful sniff at his knee — but if
he reaches to stroke her scarred muzzle she pulls back, not in
alarm but maintaining distance.
Brisbin acquired more of these feral pariahs,
which he'd taken to calling Carolina dogs, from shelters and
from the wild in South Carolina and Georgia. A number of
them came from land surrounding large federal reservations, like
Fort  Gordon
near Augusta, where much of the terrain remains undeveloped and
undisturbed. Brisbin kept his Carolinas in a complex of
kennels in an 18-acre enclosure where they could roam in the
woodlots and fields. They started producing puppies —
and surprises.
Regardless of their origin,
the Carolinas did things never before observed in domestic dogs.
They had peculiar breeding cycles, starting with a rapid-fire,
thrice-annual estrus in young females (perhaps a way to ensure
quick breeding before diseases like heartworm took their toll)
that later settled into seasonal reproductive cycles peaking
in spring and late summer — the period, Brisbin notes, when
small mammals are most abundant. Some pregnant females dug elaborate
underground dens in which to give birth, unlike most domestic
dogs, which usually just crawl under a porch or into a handy
pile of brush. When she was in estrus or after her puppies were
born, a captive female would carefully cover her excrement by
scraping sand over it with her nose.
To Brisbin's bafflement,
the animals also dug what he calls "snout pits," hundreds
of small, conical depressions in the dirt that exactly fit the
dogs' muzzles. Most snout pits are dug by females, between
September and January. The dogs seem to be eating something,
"but when I pull them out and look, there's never anything
there," Brisbin says. They are particular about where
they dig, and Brisbin can only conclude they're eating the soil
itself, perhaps for its minerals.
With time, Bris
became convinced he had stumbled onto something unique. The
size, shape, color and behavior of the Carolina dogs, so similar
to the the traits of other primitive canids, suggested they might
be a relic of the first dogs to enter the region. He compared their skulls with
those of Indian dogs from 2,000-year-old archaeological digs
at Savannah River; they were similar, but there was too much
individual variation among the fossils to be certain.
But the fact that Carolina dogs
are most often found in wild, swampy, sparsely settled regions,
instead of more heavily populated areas where stray dogs are
most common, is a strong indication to Brisbin that these are
more than just mongrels. Others agree; Bris has convinced
both the American Rare Breeds Association and the United Kennel
Club to recognize the Carolina dog. As with any registered breed,
there is now a Carolina dog studbook to document and control
breeding, and Brisbin's animals have even started winning "best
in show" at multiple-breed dog shows.
They are, of course, individuals.
There are Lucy and Cici, both captured as wild pups, who vanish
down their den holes before a stranger even steps from Brisbin's
car. Dibble, the dominant female of the pack, is a bit standoffish,
but Bo Pup, an adolescent, is all over me in seconds with open-mouthed
greetings. Surrey is a medium-sized female, daughter of Horace
and Marion; Morgan is a solid, friendly chap whose drop ears
belie his Carolina dog genes.
If Marion is emblematic of a pariah
dog's ancestral shyness, Taz is the polar opposite: a Carolina
dog deeply, passionately, enthusiastically in love with people.
He's Brisbin's home dog, a white-and-tan whose parents were both
taken from the wild. Bris is bringing him up through the ranks
of obedience training, aiming for the highest level. On the lead,
Taz reacts instantly to hand and voice signals, but when the
leash comes off as we walk in the woods, he vaults up steep banks
with ease, and scrambles out on fallen tree trunks that span
20-foot-deep gullies.
On an oppressive
June evening, with the temperature still above 100 degrees Fahrenheit
and the sun a fierce red ball in the western sky, I walk with
Bris and a dozen or so Carolinas across Banbury Cross Farm, near
Aiken. The dogs lope easily ahead of us, the low sun backlighting
them, creating little moving nimbi of gold. Billy Morgan Benton,
a big, outgoing man with dark hair slicked back wet under his
cap, whistles to his pack, he and farm owner Jane Gunnell breed
the dogs here, working with Brisbin to establish the Carolina
dog as a domestic pet. They are frolicsome, friendly animals,
Gunnell says, but out in the wooded nooks and weedy fields of
the farm, their primitive traits become obvious.
The dogs are
ginger, a red-brown that fades to pale buff on the flanks and
belly, the same color as fallen pine needles and dead grass.
They fan out through a low scrubby field, moving into the damp
breeze, zigzagging and coursing with their noses low and their
curved tails at half-staff.
Suddenly one dog makes a sidestep,
its supple neck arching; the tail snapping high, the longer,
whiter hairs along its underside flaring, reminding me of a deer.
The effect on the rest of the pack
is electric. Within seconds, all the dogs converge on the spot,
tails moving like semaphore flags. One plunges its head into
the grass with the speed of a heron's stab, but it misses. Something
small skitters through the weeds, and another dog leaps, coming
down with mouth and front feet together, a predatory exclamation
mark — Bam! There is a tiny squeak, and the mouse
vanishes in one gulp.
"I would suggest that you're
watching a reenactment of a dog pack out hunting 8,000 years
ago," Brisbin says. While he doesn't claim that Carolina
dogs are direct, genetically pure descendants of the original
dogs that crossed the land bridge, he believes that they re-create
their look and behavior.
"The Carolina dog is a hypothesis,
he says. "A hypothesis that there still exists in certain
parts of the United States, most likely in relatively uninhabited
broad expanses of natural habitat within the Southeast, remnant
groups of dogs whose morphological, behavioral, ecological and
genetic traits may approximate those of the first dogs to enter
North America.
"It's all part of the package.
Morphology and behavior go hand in hand," Brisbin says,
gesturing to the lean shape of a nearby dog snuffling through
the underbrush. That sinuous, blue-heron neck doesn't seem relevant
without the pointed muzzle for stabbing at prey, and the upright
ears for sharp hearing, and the long tail with its pale underside
for signaling to the rest of the pack. Whether the Carolina dog
is an ancient holdover or a modern throwback, its  shape
and behavior make a lot of evolutionary sense.
Genetics may
tease out the origins of the Carolina dog, but so far the
results are mixed. Recently, Brisbin and his colleague Travis
Glenn, a molecular geneticist at SREL, have been looking at the
mitochondrial DNA (mtDNA) of Carolina dogs — the genetic
material passed down through the maternal line, and a potent
gauge of relationships among animals.
When the mtDNA
from Carolina dogs, dingoes, singing dogs and a variety of domestic
breeds are compared, a phylogenetic tree — a sort of family
tree showing their relationships — can be made. In this
tree, the Carolina dogs tended to clump together near the base,
an intriguing though tentative result that suggests the Carolina
dogs may possess primitive genetic traits.
"Most
of the dogs coming out at the base of the tree are Carolina dogs
or dingoes," Glenn says. "If there were no basis to
the argument that Carolinas are primitive, they'd be all over
the tree, but they're grouped together." Glenn, who had
initially assumed the Carolinas were just domestic dogs, admits
he was stunned when he saw the results. "I had to go out
for a beer."
Brisbin is
cautious in interpreting the results, especially since the mtDNA
sequences of some domestic dogs also grouped with the Carolinas
at the base of the tree. "It's interesting that at a preliminary
stage, most all of the Carolina dogs turned out to be primitive"
— but so did boxers, German shepherds and Labrador retrievers,
among others. It will take more research
to sort out exactly what secrets are hiding in the "yaller"
dog's genes.
The Carolinas
are part of what Brisbin calls "the great arc of the red dog,"
the worldwide distribution of pariah canids. From their probable
point of evolution somewhere in Southwest Asia or the Middle
East, the ancestors of today's domestic dogs spread out in tandem
with humans into Africa; and southeast through Java, Australia,
New Guinea and then island-hopping through the South Pacific
in rafts and canoes; north through Korea, Japan, Siberia and
then into North and South America.
In remote corners of the world,
away from the later waves of European dogs that hybridized local
varieties out of existence, some of the original dogs still survive.
Unlike the Carolinas, their ancient lineage is undisputed. The
most intriguing, and perhaps the most primitive, is the New  Guinea singing dog.
Low-slung and muscular, weighing about 25 pounds, with short
legs, a long torso and a wide face, it is a curiously feline
dog with an ability to climb and jump that is unmatched by any
other breed — a handy trait in the sodden, jumbled forests
of the New Guinea mountains, where it can scramble up trees like
a cat. The name comes from its weird, harmonic howls, whose unearthly
qualities prompted one of the highland tribes to claim the Creator
had replaced the dog's tongue with the quill of a cassowary,
a native bird. These dogs are truly wild animals and rarely seen.
Although singing
dogs have been in New Guinea for at least 4,000 years,
living examples were only discovered by the outside world
in the 1950s. At that time, they were classified as a separate
species of wild canid, although today they are officially grouped
with the domestic dog. Unfortunately, purebred singers
have all but vanished from New Guinea as European dogs
have moved into the highlands. Today only about a hundred exist
in captivity, the descendants of a handful of wild-caught animals,
and most of those have been neutered or are too old to breed.
Brisbin has a couple of pairs and has been working closely with
Janice Koler-Matznick of Central Point, Oregon, an expert on
singers who has founded the Primitive and Aboriginal Dog Society
to promote the conservation of ancient canids.
As the singing
dog adapted to the rigors of life in the wet forests of New Guinea,
so did dogs elsewhere evolve to fit the local climate and conditions-
both through natural selection and selective breeding by humans.
There may have been hybridizing with wolves, coyotes and other
wild canids, further stirring the genetic pot. Based on skeletal
remains found at ancient village sites, it appears there were
recognizably different types of domestic dogs thousands of years
ago, from tiny toy-size breeds to animals with the heft of modern
mastiffs.
While bones
tell part of the story, they say little about a dog's outward
appearance. Fortunately, in the case of early dogs in the Americas,
pre-Columbian art, the accounts of early explorers
and works of frontier artists fill in some of the blanks. The
average Indian dog apparently looked like a dingo — with
a fairly short coat, upcurved tail and upright ears. Judging
from 19th-century paintings, the Iroquois raised dogs that would
look at home in Brisbin's pack of Carolinas.
Along the
Northwest coast around Vancouver Island and the Olympic Peninsula,
the Makah and Coast Salish tribes kept two breeds, both now extinct
— a typical, dingo-like village dog, and a smaller, longhaired
variety with a tightly curled tail raised exclusively for its
fur, which was woven into blankets. Dogs in the Arctic, sub-arctic
and Great Plains, on the other hand, resembled wolves, with large
frames, heavy coats and shaggy tails. Many explorers said they
could scarcely tell the difference between a wolf and a Plains
dog, which was well-known for its ability to drag heavy loads
for humans.
"There's no doubt
that the dog is closest to the wolf," says Juliet Clutton-Brock
of the Natural History Museum of London, and one of the world's foremost
authorities on the prehistory of domestic animals. Studies since
the 1950s reveal many similarities between wolf and dog morphology
and behavior, and experts have formed a consensus: the more than
400 breeds of domestic dog, from Chihuahuas to Saint Bernards,
were descended from one of the small, southern Asian subspecies
of the gray wolf — perhaps the Arabian wolf, or the Indian
wolf immortalized by Rudyard Kipling.
The oldest
fossils of what are undisputedly dogs date from about 11,000
or 12,000 years ago in Southwest Asia, making dogs the oldest
of all domesticated animals. Archaeozoologists — scientists
who study the remains of animals in association with humans —
assumed that the domestication process would have started much
earlier, perhaps 15,000 years ago, in conjunction with the rise
of permanent villages and the advent of agriculture.
But in 1997,
a team led by evolutionary biologists from the University of
California at Los Angeles dropped a bombshell. After analyzing
DNA from wolves and wild canids around the world, as well as
from nearly 70 breeds of dogs, they concluded that dogs and wolves
 probably
split off from each other originally more than 100,000 years
ago — almost the same time that anatomically modern humans
were first emerging, and long before anyone suspected domestication
was possible. While hailed by some molecular biologists, the
UCLA findings have been questioned by paleontologists and archaeozoologists.
Last August, at a symposium on the history of the domestic dog
at the University of Victoria in British Columbia, sponsored
by the International Council for Archaeozoology, the controversy
was a major topic.
One explanation
that might reconcile the archaeological record and the DNA findings
is that the dog's ancestors were wolves that split off from other
wolf lineages 100,000 years ago, even though dogs themselves
didn't evolve until more recently.
While debate
swirls around the timing of dog domestication, some experts are
taking aim at the fundamental notion that dogs and other animals
were domesticated through a human-directed process.
"The
standard explanation of how domestication began — that people
brought in young wild animals, which they tamed and bred over
many years to produce domestic stock — is a myth,"
argues archaeozoologist Susan Crockford, an expert on the Northwest
wool dog, and the organizer of the Victoria symposium.
For quite
a while, biologists have believed that domestication took place
over a long time: a period that would cover taming an animal,
molding it from a wild form into a physically and behaviorally
different creature. That transition period should provide
lots of intermediate forms in the archaeological record —
only it doesn't. Instead, the bones of dogs suddenly pop up in
archaeological sites about 12,000 years ago, at the same time
humans were abandoning their hunter-gatherer culture.
Whether you're
talking about dogs, sheep, cows, goats, pigs or water buffalo,
there are consistent differences between the wild and domesticated
forms. Compared with their wild cousins, most domestic mammals
tend to be smaller, have shorter snouts, smaller brains and are
more likely to be piebald or solid in color; they are more docile,
reproduce at a younger age, have larger litters and have reproductive
schedules, such as multiple breeding seasons in a single year,
that differ from those of wild animals. Such changes also occur
in domestic birds.
Interestingly,
all these differences are a consequence of changes in developmental
rates, especially while the animal is young, which result in
a sexually mature adult with the size and some of the characteristics
of a juvenile of its ancestor — a condition known as paedomorphosis.
And those developmental rates, in turn, all appear to be controlled
directly or indirectly by a single biochemical: thyroxine, a
hormone produced by the thyroid gland, which in turn regulates
a suite of crucial growth and developmental genes. Thyroxine,
Crockford believes, was the key to domestication changes.
Crockford
theorizes that in a sense, wild canids  domesticated
themselves. By creating a new environment, one in which food
supplies were available to those wolves able to tolerate the
presence of people, humans set the stage for rapid evolution.
Fear is controlled, in part, by the adrenal gland, and adrenaline
production, in turn, is one of the many biological functions
controlled by thyroxine.
In Crockford's
view, the less fearful wolves would thrive near settlements,
scavenging garbage middens and filching meat from drying racks,
breeding among themselves and reinforcing those attributes. Natural
selection would favor canids with thyroxine levels that produce
lower adrenal response. Any pups born with a more fearful nature
would simply drift away from the villages, back into the wilderness.
After just a few generations, she believes, the wolves living
near humans would exhibit reproductive, physical and behavioral
differences, triggered by their new thyroxine patterns, that
would set them apart from their wilder counterparts. They would
have become primitive dogs. Only much later, long after primitive
dogs had become genetically distinct and reproductively isolated
from wolves, did humans begin exerting artificial selection to
create distinct breeds.
Crockford
cites intriguing evidence for her hypothesis. For 20 years starting
in the 1950s, researchers in Siberia, trying to create a strain
of silver fox that would be easier for fur-farm workers to manage,
began selecting breeding pairs strictly on the basis of how calmly
they behaved around people. Unintentionally, the Soviets were
selecting foxes based at least in part on their thyroxine levels,
Crockford contends. Within just 20 generations, foxes in the
fearless strain had become markedly smaller, had undergone changes
in their reproductive schedule, and had developed floppy cars,
curled tails and piebald coats — precisely the traits that
often separate dogs and wolves, and all of which are under the
control of thyroxine.
"It may have taken only about 40 years, at two years per
generation, for wolves to evolve into early dogs — perhaps
more than that, but we can now look at that number as some sort
of minimum. And 40 years is almost certainly too fast to pick
up intermediate stages in the archaeological record", Crockford
argues.
While some
scientists look toward the dog's past, others are casting a worried
eye toward the future of primitive breeds. Brisbin thinks the
Carolina dog is relatively secure, although the expansion of
coyotes into the Southeast may be causing a reduction in their
numbers. But others, like the Tengger dog in Java and the Falkland
Islands "wolf,"' are extinct, and more are threatened.
Conservation organizations, already overburdened and overextended,
rarely pay attention to domestic animals — even though many
breeds represent important genetic diversity, and an irreplaceable
slice of human and natural history.
Which brings
us back to the Carolina dogs. Are they, as some people claim,
a direct link to the aboriginal past, or a recent construct of
the canine melting pot?
Brisbin will
keep working toward a major genetic study of the dogs. He also
hopes to track wild Carolinas by fitting them with radio collars,
to learn more about their habits, territory and prey.
But even if
further research proves the Carolina is of modern origin, it
still has much to tell us about natural selection and how, in
a relatively short time, stray dogs were molded into an animal
well suited to the wet, hot coastal plain of the Southeast. And
that lesson alone, Brisbin and other researchers believe, makes
this shy, lovely animal worthy of study and conservation. |
