The Canine-Human Success Story

Dogs ARE human’s best friend

Jocco (standard poodle), Henry (Vizsla) and the author

Genetic success is defined by numbers and dogs are a huge genetic success story.  World-wide population estimates of dogs range from 700 million to 1 billion, usually listed behind the most populous large mammalian species of humans (7.8 billion- 2020), followed by cows, and sheep.  For cat lovers, there are about 400 million worldwide, so they are also doing quite well spreading their genetic material around the globe.  Dogs’ lives are so intertwined with humans that they are the only mammalian species besides rodents who live everywhere humans do.  You will find dogs from the Arctic to deserts to equatorial jungles.

Wolves and dogs derived from a common ancestor and so are close canine cousins. So close, in fact, that interbreeding is possible.  

Although dogs and wolves share 99.8% of their genes, wolves are an endangered species- often feared and hunted by humans, while dogs are welcomed into human homes, often to snuggle with our babies.

Photo credits: “Wolf 2” by Fremlin is licensed under CC BY 2.0 and “Dog meet baby” by Lawrence

The hallmark characteristic of dogs are their adaptability, both physically and behaviorally.  There are about 350 dog breeds and innumerable mixed-breeds creating even more morphological variation.  This high level of physical variation is not observed in other species and there is one theory that little bits of DNA (short interspersed nuclear elements or SINES) can more easily jump around in the dog genome to modify gene expression.

 Just look at the variation in size, coat color, shape of nose, ears, body, head observed in this montage. 

Dog Breed Composite:  Photo Credits below.

Not all dogs live as pets.  Estimates range from 20% of the canine population (Bern) to about half.  The US has the highest numbers of pet dogs, at 38% of households.  There are statistics out there because pet products are big business! Yet the majority of dogs are village dogs who live on the edges of human activity, eating handouts, scraps, and garbage (Bern).  Now I understand why people from some cultures consider it filthy to have a dog inside a home.

The majority of dogs worldwide live as village or street dogs

Left: “Street dogs, Udaipur” by Dey

Right: street dog eating trash by Hanumann

According to Dr. Gregory Berns, a neuroscientist who images the brains of awake dogs, “Dogs are one of the few [species] that can learn from other species.  Herding dogs, for example, learn by observing sheep and cattle.  And all dogs learn by observing humans and other members of their households, just like Callie [his dog] learned how to open doors.”  The success of dogs, even village dogs, depends in part on their uncanny ability to tune into the behavior of humans.

But if dogs and wolves are so similar genetically, are they really that different in temperament with humans?  In a special study performed at the Dept. of Ethology, Eotvos University in Hungary, wolf cubs and dog puppies were individually hand-raised in a home environment with constant human contact from 3 – 24 weeks of age and their behaviors measured as they grew.   At first the wolf cubs didn’t seem different from the puppies, but within weeks, the wolves paid little attention to the humans, seldom made eye-contact, and eventually became so wild they could no longer be kept in the volunteers’ homes. Further study of the two populations showed that although wolves could be taught to walk on a leash, sit for a treat and come when called, they do not cue into human behavior the same way puppies do. There is something unique about the dog-human relationship.

Dogs were domesticated somewhere from 15,000 to 40,000 years ago.  That would place it before the beginning of agriculture and the domestication of other animals (James Serpell).  There are two hotly debated theories of dog domestication.  One is the commensal scavenger hypothesis, basically the idea that dogs self-domesticated by hanging out on the fringes of human gatherings, and the other, the cross-species adoption hypothesis, is that humans sought out various baby animals as pets and the precursor to wolves and dogs was the most successful species to affiliate with them beyond the juvenile stage. 

Human-dog interactions show up in pre-historic cave paintings and other art, including this collection from Saudi Arabia described by archeologist, Maria Guagnin.

Modern day Canaan dogs from the Arabian Peninsula (left) and rock art from Shuwaymis (right).  Dogs aiding in hunting activities, with two who appear to be on leash (below).

Dog domestication may have happened first in Europe, Asia and/or the Middle East, but we do know that when Europeans first colonized the Americas and brought their dogs with them, there were already dogs present.  This interesting video (25 min) describes how Native American cultures already had breeds specialized for different purposes, such as hunting, herding, and pack dogs.  Salish wool dogs with a fuzzy white coat were sheared in the spring to create special blankets and the Chihuahua in Mexico were believed to have healing skills by sitting on areas of human ailment.  Dogs moved into the Americas pre-European contact in at least two waves of migration from Asia along with human migration. Unfortunately, European disease had a devastating effect on these native dog populations as well on the humans, and most of the original pre-contact breeds are now gone, although Alaskan malamutes and chihuahuas are survivors.  Even so, with much interbreeding, most of the pre-contact dog DNA, as determined from early canine remains, has been replaced with European canine DNA.  

Dogs and humans have an amazingly intertwined history, each benefitting the other, so that many of us would find it hard to live happily without them.  I am certainly one of them.

Key reference: How Dogs Love Us: A Neuroscientist And His Adopted Dog Decode The Canine Brain by Gregory Berns

Donna Barten is a novelist and scientist awaiting publication of her debut novel, Breathing Water.

Dog Breed Composite Photo Credits. Photos by Donna Barten unless otherwise noted. Golden Retriever (Rusty) by Craig Cox; Great Dane, The Walk to Save Great Danes by Warchild; Cavalier King Charles Spaniel puppy by Judith MacMunn; Boxer (Eli) by Jaylene Piraino; Miniature Poodle (Max) by Tom Callard; Mixed breed reservation dog by Michael Barten; Bulldog (Nikko) by sabianmaggy; Shiba Inu (Japanese Dog Breed) by marcoverch; Cocker Spaniel (Tucker); Whippet – Dallas Dog Shows by M.P.N.texan; Yorkshire Terrier (Tucker); White Boxer (Bosco) by Jaylene Piraino; Dachshund Dog Breed by shamaasa; Chihuahua– La Main – The Main – Chiwawa by Humanoide; Afghan Hound by tarentula_in; Sweet lil’ hunting dog (Black lab) by m01229; Cavalier King Charles Spaniel (Berklee); Irish Setter (Bonnie); Boston Bull Terrier (Franklin) by Jaylene Piraino; Biggelow the SharPei – regal by Biggelow Bear Bags 2

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