Not quite as obvious as it might seem.

Considering that this blog is called Learning from Dogs, there has been precious little published about the animal species known as Canis familiaris; the classification of the domestic dog.  Let me try to correct that.

So, this reference explains:

The subdivision of Canidae into “foxes” and “true dogs” may not be in accordance with the actual relations; also, the taxonomic classification of several canines is disputed. Recent DNA analysis shows that Canini (dogs) and Vulpini (foxes) are valid clades (see phylogeny below). Molecular data imply a North American origin of living Canidae and an African origin of wolf-like canines (Canis, Cuon, and Lycaon).

Currently, the domestic dog is listed as a subspecies of Canis lupus, C. l. familiaris, and the dingo (also considered a domestic dog) as C. l. dingo, provisionally a separate subspecies from C. l. familiaris; the red wolf, eastern Canadian wolf, and Indian wolf are recognized as subspecies. Many sources list the domestic dog as Canis familiaris, but others, including the Smithsonian Institution and the American Society of Mammalogists, more precisely list it as a subspecies of C. l. familiaris; the red wolf, eastern Canadian wolf, and Indian wolf may or may not be separate species; in the past, the dingo has been variously classified as Canis dingo, Canis familiaris dingo and Canis lupus familiaris dingo.

However a recent paper published by Nature magazine throws some interesting light of the development on the domestic dog.  As the article preview explains:

The genomic signature of dog domestication reveals adaptation to a starch-rich diet

The domestication of dogs was an important episode in the development of human civilization. The precise timing and location of this event is debated and little is known about the genetic changes that accompanied the transformation of ancient wolves into domestic dogs. Here we conduct whole-genome resequencing of dogs and wolves to identify 3.8 million genetic variants used to identify 36 genomic regions that probably represent targets for selection during dog domestication.

Nineteen of these regions contain genes important in brain function, eight of which belong to nervous system development pathways and potentially underlie behavioural changes central to dog domestication. Ten genes with key roles in starch digestion and fat metabolism also show signals of selection. We identify candidate mutations in key genes and provide functional support for an increased starch digestion in dogs relative to wolves. Our results indicate that novel adaptations allowing the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in the early domestication of dogs.

The BBC News website picked up on this:

Dog evolved ‘on the waste dump’

By Jonathan Amos Science correspondent, BBC News

Anyone who owns a dog knows that it will rummage around in the kitchen bin looking for food, given half a chance.

But this annoying behaviour may have a more profound undercurrent than we realise, according to scientists.

A new study of dog genetics reveals numerous genes involved in starch metabolism, compared with wolves.

It backs an idea that some dogs emerged from wolves that were able to scavenge and digest the food waste of early farmers, the team tells Nature journal.

No-one knows precisely when or how our ancestors became so intimately connected with dogs, but the archaeological evidence indicates it was many thousands of years ago.

One suggestion is that the modern mutt emerged from ancient hunter-gatherers’ use of wolves as hunting companions or guards.

But another opinion holds that domestication started with wolves that stole our food leftovers and eventually came to live permanently around humans as a result.

Anyone who owns or loves dogs will find this article fascinating.  Jonathan Amos goes on to say:

“This second hypothesis says that when we settled down, and in conjunction with the development of agriculture, we produced waste dumps around our settlements; and suddenly there was this new food resource, a new niche, for wolves to make use of, and the wolf that was best able to make use of it became the ancestor of the dog,” explained Erik Axelsson from Uppsala University.

“So, we think our findings fit well with this theory that the dog evolved on the waste dump,” he told BBC News.

Dr Axelsson and colleagues examined the DNA of more than 50 modern dogs from breeds as diverse as the cocker spaniel and the German shepherd. They then compared their generic genetic information with those of 12 wolves taken from across the world.

The Swedish-US team scanned the DNA sequences of the two types of canid for regions of major difference. These would be locations likely to contain genes important in the rise of the domesticated dog.

Axelsson’s group identified 36 such regions, carrying a little over a hundred genes. The analysis detected the presence of two major functional categories – genes involved in brain development and starch metabolism.

In the case of the latter, it seems dogs have many more genes that encode the enzymes needed to break down starch, something that would have been advantageous in an ancestor scavenging on the discarded wheat and other crop products of early farmers.

Do go across to that BBC item and read the rest of the article.

That article and the paper in Nature magazine resonate strongly with an article written on the Dr George Johnson on Science website.  In fact I referred to the George Johnson piece when I first published the Dogs and integrity side piece in July 2009. (My how time flies!)  As that George Johnson piece reveals:

This week I found myself wondering about Boswell’s origins. From what creature did the domestic dog arise? Darwin suggested that wolves, coyotes, and jackals — all of which can interbreed and produce fertile offspring– may all have played a role, producing a complex dog ancestry that would be impossible to unravel. In the 1950s, Nobel Prize-winning behaviorist Konrad Lorenz suggested some dog breeds derive from jackals, others from wolves.

Based on anatomy, most biologists have put their money on the wolf, but until recently there was little hard evidence, and, as you might expect if you know scientists, lots of opinions.

The issue was finally settled in 1997 by an international team of scientists led by Robert Wayne of the University of California, Los Angeles. To sort out the evolutionary origin of the family dog, Wayne and his colleagues used the techniques of molecular biology to compare the genes of dogs with those of wolves, coyotes and jackals.

Wayne’s team collected blood, tissue, or hair from 140 dogs of sixty-seven breeds, and 162 wolves from North America, Europe, Asia, and Arabia. From each sample they extracted DNA from the tiny organelles within cells called mitochondria.

While the chromosome DNA of an animal cell derives from both parents, the mitochondrial DNA comes entirely from the mother. Biologists love to study mitochondrial DNA because of this simple line of descent, female-to-female-to-female. As changes called mutations occur due to copying mistakes or DNA damage, the mitochondrial DNA of two diverging lines becomes more and more different. Ancestors can be clearly identified when you are studying mitochondrial DNA, because clusters of mutations are not shuffled into new combinations like the genes on chromosomes are. They remain together as a particular sequence, a signature of that line of descent.

Do read the full article here.

Finally, just watch this short trailer for a BBC Horizon screened in early 2010.  (Wet eyes warning!)

So the next time you look a dog in the eyes or hug their lovely furry body, think how far back the relationship goes and marvel at how much we have learnt from them.

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