Sunday, January 27, 2013

Ray Coppinger guest-blogs about starch digestion mutation in dogs

On January 23, 2013, a groundbreaking study was published by a team of canine geneticists from the University of Uppsala, Sweden, announcing they have identified key mutations in three genetic regions that allowed the traditionally carnivorous wolf, or pre-curser to dogs depending on your position,  to subsist on a starch-rich diet.  (Read my post in Bark magazine.) Here, canine expert Ray Coppinger comments on the paper.
Ray Coppinger at Wolf Park, Indiana, USA


Evolutionary biologist Ray Coppinger, professor emeritus from the School of Cognitive Science, Hampshire College, Massachusettes, has raced, bred and studied dogs all over the world for decades.  Ray and his wife, Lorna, developed the modern and controversial theory of how dogs evolved by natural selection, in contrast to the more consensus view that people intentionally domesticated dogs by artificial selection.  The Coppingers argue that dogs, shaped by the environment they find themselves in, evolved as one of the all time most successful scavengers. The Coppingers theorize that over time, humans adopted these wild dogs, continuing to shape them further into diverse forms.

Dog scavengers at Mexico City dump
Photo by Virgiania Broitman

Although the journal article doesn't say when the mutations occurred, the authors suggest that the adaptation was surely useful for opportunistic animals that were scavenging waste near ancient farming communities. 
First wolf tasting her new grain based diet?
Does it support the village dog domestication theory?  Professor Coppinger comments below.


**

"Dogs and wolves are the same species.  They are subspecies of each other.  Sub species simply means they are polymorphic for many characteristics. And THAT simply means that they vary in the shape of particular characteristics. For example, dogs and wolves differ in size, shape, faces, color, and behavior.  
Dog skull (above) compared to wolf skull
Jawbone of dog and wolf
As the muzzle foreshortens in the dog,
the teeth crowd together.  


The eyes become rounder and move forward on the skull.
Last week an article in the Journal Nature showed brilliantly that dogs and wolves differ in another trait, their ability to digest starch. Wolves can digest starch, but dogs are better at it.  “Better” means they can do it more efficiently.  What that means is that in a niche full of starch, dogs would out-compete wolves.  All niches are limited, says Darwin, and more individuals are born than the niche can support.  Natural selection will favor the most efficient individuals.  
An efficient niche-filler
Ethiopian Village Dog
Photo courtesy Alessia Ortolani
The Nature paper concludes dogs are better adapted to living in the grain-rich environment created by humans. When did dogs get those genes for digesting grains?  
Village dogs feeding at dump site in Ethiopia.
Photo courtesy Alessia Ortolani
How such a mutation becomes dominant in a population is a complicated process, but certainly isn't instantaneous.  The assumption would be that "wolves" were already occupying the dump nicne and then came the mutation.  So the initial population didn't have the "new and improved" genes for digesting starch.  When did the new and improved system evolve? We don't know, nor do the authors suggest a time line.  Certainly not right at the beginning, and it could have come only a few hundred years ago. Or although unlikely, even with the invention of dog food.  More study is needed. 
Some of us who support the village dog domestication theory would like to think that it happened in the Neolith period, after humans developed their sedentary life based on growing grain crops. We would also like to believe that the adaptation of the wild species – call them wolves – into dogs was the result of natural selection for being tame around humans and being able to digest their starchy waste products. 
Village dogs at Mexico City dump
Photo courtesy of Ray Coppinger
Does the Nature paper suggest how dogs evolved?  I wish it did because I am sure it would support the Village Dog hypothesis.  But it also doesn't support the possibility that dogs could have evolved before the Neolith, by artificial selection, meaning people taking wild wolf pups from the den, taming and domesticating them. Some people like me and my students who actually have taken wolves from the den and laboriously tamed them, think this latter hypothesis is silly, but the Nature paper doesn’t rule out that possibility."
Read more about the dog's adaptation to a starch-rich diet at these links:

  • The genomic signature of dog domestication reveals adaptation to a starch-rich diet, Journal Nature, published on-line, January 23, 2013.
  • The Bark blog
  • Author Mark Derr comments on the study.
  • This link will take you to a description of a 2010 lecture about dogs at the Mexico City dump by Ray Coppinger: The Mexico City dump, an island paradise of dogs, a fresh view of an old relationship

What do you think?  Comment here or go to my post at Bark and leave a comment there.

Monday, January 21, 2013

Dalmatian history and vintage photos


January 22nd is National Polka Dot Day and that means it's a good day to celebrate Dalmatians.
Who doesn't love a spotted pup?

A Dalmatian named Timmy was my very first dog.
Dr. Barkman and Timmy 1952
My grandfather, William McNally, was a New York City fireman, so all the family dogs were Dalmatians.  Teddy is in the picture below.  Note my grandmother's matching spotted dress.  (Read more about spots, dots and quilts at my sister's blog, Barbara Brackman's Material Culture.)

Grandpa's dog Smokey, 1940

Documentation about the breed's origin and purpose is spotty.  
Dalmatian 1790

Whether Danish or Croatian, guard dog or field hound, the elegant pooch has always filled the role of companion.
1865 (Library of Congress)


1880s
1940s

Although Dalmatians are surely descendants of hunting dogs, hunters were not fans.  In 1785, a piece in the Sportsman's Dictionary described methods for choosing the best pup in the litter:

“Those that are spotted with a dun colour are esteemed of little value, being faint of heart, and cannot endure much labour...  But if white-hounds are spotted with black, experience tells us they are never the best hare hunters.  Choose the one of black, brown, or one colour and drown the rest...the spotted are not much esteemed."   


The author added, perhaps as an after thought, "Though of hounds, the spotted are to be valued.”
A spotted hound

D-O-G NEEDS J-O-B
By the mid 1800s the under-employed Dalmatian found a noble profession in firefighting.


Moving slightly ahead of the horses, dogs cleared streets, giving coaches quicker access to fires.


But snobby huntsman still couldn't say anything nice:
"The Coach Dog was never fit to be the pet of any one but a stable man.  It is simply a show dog possessed of a cross disposition, but handsomely marked and the continuation of a fad that made it an appendage of a rich man's establishment."

Success is the best revenge.

Victorian dog breeders in the UK fancied the Dalmatian. Claiming the much-maligned dog as their own, breeders shot back,
 “So now, the evil forebodings as to the forthcoming extinction of this clever and interesting animal are like to come to naught."  
1905 Kennel Club Ch. Rugby Bridget
Photo: Leighton's New Book of the Dog (1907)


And as they say, the rest is history.

Find out why Dalmatians need their spots:
Genetic deafness and its relationship to skin pigmentation



Saturday, January 12, 2013

Why do dogs wag their tails?

Every dog-person knows that emotions are communicated via the tail.  But WHY dogs wag their tails, from a biological point of view, continues to be a mystery.  
Tail wagging is a fairly unique trait. Dogs do it. Wolves don't, at least not to excess. Part of the reason has to do with tail anatomy.

Wolves have bushy tails that 
they carry almost parallel to their backs.

Dogs, on the other hand, 
have tails of all shapes and sizes. 
 Read more about dog tail shapes here.


Dogs, wolves and coyotes have anal glands that secrete signature scents.    Another scent source is a gland on the outer part of the tail called the supracaudal gland. Course black guard hairs indicate its location.

This is what it looks like on a coyote.

Whether or not domestic dogs retained the gland during evolution remains unclear.  It's possible that some breeds have it and others don't.  Dogs with certain kinds of coats have a dark spot where the gland would be located. My dog Chance has the black spot. But I can't tell if he has the gland.  


Tail Waggers
Unlike their adult counterparts, wolf pups wag their tails.  Maybe the little guys don't have fully developed scent glands, so wagging is needed to amplify the odor and push the smell around. As they get older, scent glands become more developed. When wolf pups reach sexual maturity, tail wagging wanes. 

Why wag your tail when you can distribute 
your scent more efficiently by a rub and a rolicking roll.  


So why do dogs wag their tails?
Some evolutionary biologists believe that domestic dogs are wolf pups in dog clothing. As wolves changed to dogs, biological development was arrested in such a way that typical dog behaviors, like playing, ball retrieving, tail wagging and even barking, are left over remnants of wolf puppy behaviors.

Tail wagging is a behavior that's lost its original function through evolution.  Dogs wag their tails because they still can.

And that's a good thing.

Monday, January 7, 2013

Vintage Dachshund Photos

The Dachshund derives from badger hunting dogs. The old-style dog had longer legs.
Bronze, sometime between 1835 - 1860
And shorter ears.
Woodcut 1879
Victorians were the first to keep hunting dogs, including Dachshunds, as house pets, much to the annoyance of sportsmen.  By the late 1880s, doxies gained popularity in the UK as both show and pet dogs, upsetting a whole lot of Germans who continued to breed the dog primarily for hunting.

O mein Gott! Sie müssen scherzen! Wann beendet es überhaupt?


Victorians started a new craze which continues to this day:  Any breed, no matter what size or purpose, can become a house dog, although in my humble and experienced opinion, some are better at it than others.
c. 1900
One British author wrote in 1879, "The dachshund is really a sporting dog, but every one who knows the winning affectionate dog knows that he is excellently well adapted for being the companion of the gentler sex."  
Photo late 1800s
What Doxies do after a hard day's work badgering badgers.
The thing is though, Victorian breeders modified working dogs, aesthetically or behaviorally or both, to adapt to their new role as  house pets.  The old type doxie was larger, with longer legs, and must have been more than a bit of a handful to keep in a Victorian parlor, especially due to the breeds resistance to house breaking, which hasn't changed all that much.

Eventually the companion type Dachshund was bred to be smaller.

About 1915

Doctor Barkman with her sister's favorite dog, Duchess.
1957