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Archive for the ‘dog domestication’ Category

A black Italian wolf. The black trait originated in dogs and was transferred to Italian and North American wolves through introgression.

As long-time readers of this blog know, I consider dogs to be a form of gray wolf.  I do not consider Canis familiaris to be a valid taxon, because of cladistics and because of the gene flow between domestic dogs and wolves.

The extent of this gene flow was largely denied in much of the literature on wolves.  But last year, it was discovered that the majority of Eurasian wolves have recent dog ancestry. This gene flow has been going on for a while, and although people do get a bit worked up about domestic animal genes filtering into a wild species, it has been shown that the melanism in wolves that is conferred by a dominant allele originated in a Native American dog that was living in the Yukon or the Northwest Terrtories thousands of years before Columbus. Further, this melanistic allele is associated with higher immune responses, and there is evidence for natural selection favoring black individuals following a distemper outbreak.

In a paper released this week in the European Journal of Wildlife Research found extensive crossbreeding between dogs and wolves in agricultural landscapes in Central Italy.  The authors estimate that about half of all wolves in this region have recent dog ancestry, and they think it is because humans have disturbed wolf habitat to have agriculture.

Of course, humans, wolves, and dogs have been living in Italy alongside agriculture for thousands of years. Dogs and wolves have been mating ever since there was a population of somewhat domesticated wolves.

Further, European wolves are much better adapted than North American wolves to living in agricultural areas.  It may simply be that North Americans are much more likely to kill wolves that appear in agricultural areas and that this is what has created this asymmetry. But North American wolves tend to be in remote areas, where they rarely encounter dogs. Thus, there is not as much gene flow between dogs and North American wolves as there is between dogs and Eurasian wolves.

There is a lot of gene flow between dogs and coyotes in North America, and this finding does make sense. Coyotes do live in agricultural and urban areas much more easily than large wolves do.

I don’t think it worth becoming alarmed that dogs and wolves are mating in the wild.  Dogs have lots of interesting mutations that could be of great use to wolves as they adapt to more and more human-dominated planet. If the dog alleles are deleterious, nature will select against them, but if they are advantageous, they will help wolves thrive into the future.

So it is quite short-sighted to think of wolves as being a some sort of pure entity that must be kept free of “foreign” alleles.  If it were more widely accepted that dogs were just a domestic form of gray wolf, we would have a much easier time accepting a more holistic understanding to how these populations can continue exchange genes and adapt to new challenges.

 

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dog eye muscle

Dog domestication needs to be understood as a coevolution between our species and this form of gray wolf.  Today, an amazing finding was released in the Proceedings of the National Academy of Sciences that most domestic dogs have a muscle on the inner part of their eyebrows that allows them to make intense expressions that humans can easily read or anthropomorphize.

This muscle, called the levator anguli oculi medialis, was present in 5 out 6 dogs that were examined.  The only dog that didn’t have this muscle was a Siberian husky, which is considered a primitive dog in most dog classification schemes.

This ability to make such intense expressions that we regard as cute or “puppy dog” faces would have selective advantages in ancestral dog populations. Looking cute could elicit nurturing behavior from humans, who would make sure the dog got better food, and dogs with this muscle would have had a greater chance of survival and passing on their genes than dogs that were lacking it.

So, dogs have indeed co-evolved with humans. They have evolved several cognitive short-cuts that allow them to communicate and learn from us, and they also have evolved ways of manipulating us to benefit themselves.

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yakutian megafaunal wolf

The Siberian Times reports that the head of a massive wolf was discovered in the permafrost in Yakutia (Sakha Republic of Russia).  The head includes much of the soft tissue, as well as its golden-colored fur. The head is 40 cm (15. 7 inches long), which is pretty large when compared to modern wolf specimens.

Researchers in Russia and Japan will be examining the DNA from the soft tissue to see where it fits in modern wolf and dog phylogeny of which there are still many questions.

This wolf is a good example of what have been termed “megafaunal wolves,” very large gray wolves that lived during the Pleistocene. Robert Wayne of UCLA, a leading canid molecular geneticists, thinks that some form of Pleistocene megafaunal wolf is the progenitor of the domestic dog.  These wolves would have been expert hunters of large bison, reindeer, and horses, and they may have been semi-nomadic, following large herds of ungulates across the steppes and taiga. These semi-nomadic wolves would have been quite easily attached to humans, who were hunting and traveling in much the same way.

Also of note, this wolf has golden colored fur.  In 2015, I postulated a speculative hypothesis that the original Pleistocene wolves were more often golden in color, rather than gray.  When humans started hunting wolves extensively during the Neolithic and into modern times, wolves that were gray were selected for because they could more easily hide from human hunters. Gray color in the dead of winter in many European and Western Asian forests would have been great camouflage against the winter tree trunks and undergrowth of the forest.

Some wolves, especially tundra wolves from northern Russia and Finland, are still often golden in color, as are those in Central Asia.

Golden sable color is quite widespread in domestic dogs, but it is far less common in wolves. So it is quite possible that this coloration is so dominant in domestic dogs because the wolves that gave rise to them were this color.

This massive wolf with golden fur certainly adds some credence to my speculations, but only time will tell what this ancient, massive wolf’s head has in store for us.

But is an amazing find. No doubt about it!

Update: Researchers in Sweden, not Japan or Russia, will be examining its DNA. 

 

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hooded vs carrion crow

In Europe, there are crows. The most famous of which is the carrion crow, which looks and behaves quite like the American crow.  It is usually black, fairly omnivorous, and it often regarded as an agricultural pest.

At one point, it was believed that carrion crows existed in two distinct phases, the common all black form, which is common in Western Europe, and the phase that is marked with gray on the neck and body.  This form exists in the northern parts of the British Isles, where it has been called the grey grow, the hoodie crow, or the hooded crow. This form is found in Northern Europe, Central Europe, and the Middle East.

However, ornithologists began to notice that where their ranges overlapped, it was quite unusual to see hooded crows paired off with black carrion crows, but the traditional taxonomy still thought of the hooded and black forms as being distinct phases of the same species.

Because the two forms were rarely seen mating or paired off, it was decided to call the carrion crow and hooded crow distinct species, and this is the current understanding. The hooded crow is Corvus cornix and the carrion crow is Corvus corone. But the two birds are otherwise quite similar in terms of ecology, vocalizations, and general phenotype. All that really separates them is the coloration.

Scientists that surely there was a rather deep genetic divergence between the two species, which is why there is a species barrier between the two forms of similar crow.

However, when the genomes of carrion and hooded crows were sequenced, it was revealed that they were almost identical.

Less than .28 percent of the genome varied.  That variance was related to the fact that carrion crows have gray plumage on their neck and torso.

But that little variance is enough to create a species barrier between the carrion and hooded crows. Birds are highly visual, and when young crows imprint upon their parents, they imprint heavily upon what they see. If a young crow is raised by parents that are gray hooded, they will look for mates that are gray hooded. IF their parents are all black, they will look for mates that are all black.

However, it has also been suggested that these crows look for mates that appear not to have aberrant mutations, and this keeps the crows looking for mates that generally look like those belonging to their general family group and social circle.

Whatever the case, we have two very closely related species that do not hybridize. They probably became distinct during the heavily glaciation cycles of the late Pleistocene. One form evolved a gray hood and one evolved an all-black form. Maybe founder effect is the only real reason for this difference in plumage, for this difference in plumage is awfully random.

But that difference in plumage color is enough to create a species barrier, which, if it holds, will lead to greater and greater speciation between hooded and carrion crows.

This discovery about crows is quite interesting for what it tells us about dog taxonomy. Domestic dogs and wolves live together over a broad swathe of Eurasia, and for many centuries, dogs and wolves were regarded as distinct species. However, we have recently found that there is an extensive gene flow between Eurasian gray wolves and domestic dogs across Eurasia, and this gene flow is so significant that the majority of Eurasian gray wolves are estimated to have some relatively close dog ancestry.

Carrion and hooded crows have a clear species barrier that is likely only going to intensify as the two lineages continue to diverge with very limited gene flow. Dogs and gray wolves are not experiencing such a species barrier. Indeed, it looks like the gene flow between dogs and wolves is only going to increase as wolves move into human-dominated lands in Western Europe, and the Eurasian dog population continues to increase along with the human population.

So here we have two crows that are diverging, and the wild and domestic forms of Canis lupus that are continuing their gene flow.  Closing down gene flow is a major part of speciation, and the crows are clearly on their way.

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feral dog

Most feral domestic animals revert to a form that is roughly similar to their wild ancestor. You can see this quite dramatically in feral pigs. They generally evolve into a form that is about the same size and even coat type of the Eurasian wild boar. City pigeons look very much like the rock dove or “rock pigeon” that is their wild ancestor after just a few generations of breeding without human care.

Because village and pariah dogs tend to be mid-sized, it has been assumed that the wild ancestor of these dogs surely would have been on the smaller side as well. Therefore, the gray wolf simply could not have been an ancestor.

What actually drives the size of freely breeding and feral domestic dogs isn’t that they have some ancient alleles that force them into returning to an ancestral form.  The truth of the matter is that ecological niche and caloric restraints have a lot more to do with this phenomenon.

Dogs are unique among domestic animals in that they are the only domesticated form of large carnivoran. We have never domesticated any other species of large predatory mammal except for those Pleistocene Eurasian wolves that are at the base of domestic dogs.

Most domestic dogs are poorly adapted to living as predators, and they really don’t have to be. When dogs go feral in societies with extensive agriculture, they readily scavenge and hunt small prey. They dabble in various levels of omnivory.  Some dogs might be good at hunting deer, but deer are a lot harder to catch than garbage and groundhogs.

There is an extensive literature on mammal predator size and prey choice. The best known researcher looking at these issues is Chris Carbone, and in a 2007 paper called “The Costs of Carnivory,” which was published in POLS Biology, Carbone and colleagues looked at body mass of mammalian predators and their prey choices. If a predator weighed more than 20 kg, it hunted large vertebrates. If it weighed less than that weight, it hunted invertebrates or small vertebrates.

Larger predators get a much higher net energy gain by targeting large prey, and this large prey allows them to maintain their larger body size.

Feral and freely-breeding domestic dogs are not hunting large vertebrates. It is much easier for them to scavenge as mid-sized creatures. Natural selection would favor a moderate size, because any dogs that retained the large dog or large wolf alleles in the population would have a harder time feeding itself efficiently on these resources alone.

There are, of course, exceptions to this rule. In Uruguay, there was a population of feral mastiff-type dogs, which are called Cimarrón Uruguayo. These dogs were introduced by Europeans as working dogs, but some of them went feral. They were able to maintain their large size because they hunted livestock and game, and they were such a problem that the government placed bounties on them.  These dogs were living in a feral existence for at least 250 years, but they were able to retain a large mastiff phenotype. The feral mastiff is now being transformed into a standard breed.

However, the general rule is that village and pariah dogs tend to be significantly smaller than wolves, but this smaller size cannot be used to deny that dogs are derived from gray wolves. This smaller size is just more efficient for the ecological niche of feral and village dogs.

And it is poor reasoning to assume that dogs cannot be wolf derivatives simply because they do not evolve back into a wolfish form once they go feral.  Dogs have been domesticated for a long time, and their domestication is quite unique.  As the only large predator we have domesticated, ecological pressures create a different sort of animal than the original wild ancestor.

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4,000 year old dog

The skull of a 4,000 year-old dog has been used to reconstruct what its head may have looked like.

The dog was quite wolf-like and described by the BBC as being about “the size of a large collie.” In the UK, “collie” almost always refers to border collies, so this dog probably would have been on the large side of a medium-sized dog.

The dog’s skull was found at Cuween Hill Chambered Cairn on on Mainland, Orkney, off the northern coast of Scotland. 3D images of the skull were use to make the reconstruction, which was created in clay. The artist then made the fur look like that of a European wolf, which is not entirely unreasonable given the morphology of the skull itself.

The dog may have been used to tend sheep or guard settlements. It was clearly a respected creature in the society that interred in the tomb. Maybe it was a valued working animal or simply a totem of its people.

Whatever it was, it was clearly more wolf-like that one might have expected from a dog from this late a date. The Ancient Egyptians, who were contemporaries of these Orkney cairn tomb builders, were already breeding dogs that were quite distinct from wolves.

But the truth of the matter is that this dog was significantly smaller than most modern and contemporary European wolves, and the mainland of Scotland was full of wolves that were probably still interbreeding with domestic dogs on occasion at this time.

So the Orkney Islanders from 4,000 years ago clearly had dogs, but I imagine this dog as being something like a Norwegian elkhound, a laika, or one of the old German herding dogs, like the Thuringian sheepdog.

I would love to see more reconstructions from ancient dogs skulls.  I would love to see the Goyet Cave canid and the Razboinichya Cave “dog” undergo a similar reconstruction.

Yes, this is art, but it is art that is informed through science.

 

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coyotes

Humans and the various canids belonging to gray wolf species complex possess the most complex relationship of any two beings currently living on this earth.  At one point, they are our cherished companions, often closer to us than we ever could be with other people, and on another point, they are the reviled predators that might take a child in the night.

We have clearly defined relationships with other predators. Leopards and cougars, well, we might hunt them for sport or photograph them in the wild. But we never become closely aligned with them, except for those eccentrics who dare to keep such dangerous predators as pets.

People living in the Eurasian Pleistocene brought some wolves into their societies.  Wolves and humans should have been competitors. We should have had the same relationship with each other as spotted hyenas and lions do in Africa now.  But at some point, humans allowed wolves in.

Raymond Pierotti and Brandy Fogg demonstrate that many humans throughout the world have had some kind of relationship with wolves. In some cases, it is or was a hunting symbiosis. In others, they were totemic animals.

In their work, Pierotti and Fogg contend that the relationship between humans and wolves broke down with the rise of Christianity in the West. I don’t think that’s when it broke down. It started to become complex when humans began to herd sheep and goats.

In Kazakhstan, wolves are hunted and revered at the same time. The Kazakh people herd  livestock, so they must always worry about wolf predation. Stephen Bodio documents this complex understanding of wolves in his The Hounds of Heaven.

“They hunt them, kill them, chase them with hounds and even eagles, take puppies and rear them live, identify with them, make war on them, and claim descent from them,” writes Bodio. This description sort of fits modern humanity’s entire relationship with this gray wolf complex. We pretty much have done and continue do almost all of these things.

Wolves, coyotes, and dingoes have killed people. So have domestic dogs. In the French countryside, wolf hunts were considered a necessity to protect human life, largely because has the longest and best documented history of wolves hunting people. The dispossession of rural peasants and the depletion of game in the forests created conditions where wolves would consider humans easy prey.  Lots of European countries have similar stories. And when Europeans came to North America, they knew about the dangerous nature of wolves, even if they had never even seen one themselves.

Humans have declared war on wolves in Eurasia and in North America. The wolf is extirpated from much of its former range in Europe. They live only over a limited range in the lower 48 of the United States.

Man fought the coyote with the same venom and lead he threw at the wolf. The coyote’s flexible biology and social behavior meant that all that effort would come for naught.  The coyotes got slaughtered, but they rebounded. And then some. And the excess coyote pups found new habitat opened up with big ol’ wolves gone, and they have conquered a continent, while we continue our flinging of lead and setting of traps.

In Victorian times, Western man elevated the domestic dog to levels not seen for a domestic animals. They became sentient servants, beloved friends, animals that deserve humanity’s best treatment.

And in the modern era, where fewer and fewer Westerners are having children, the dog has come to replace the child in the household. Billions of dollars are spent on dog accessories and food in the West.  Large sectors of our agriculture are ultimately being used to feed our sacred creatures.

A vast cultural divide has come to the fore as humans realize that wolves and coyotes are the dog’s wild kin. Wolves have become avatars for wilderness and conservation, and coyotes have become the wolves you might see out your front window.

Millions of Americans want to see the wolf and the coyote protected in some way. Dogs of nature, that’s the way they see them.

The rancher and the big game hunter see both as robbers taking away a bit of their livelihood. Humans are lions. The canids are the spotted hyenas. And their only natural state is at enmity.

Mankind’s relationship to these beings is so strangely complex. It greatly mirrors our relationship towards each other. We can be loving and generous with members of our own species. We can also be racist and bigoted and hateful. We can make death camps as easily as we can make functioning welfare states.

And these animals relationships with each other are just as complex. Wolves usually kill dogs and coyotes they find roaming their territories. But sometimes, they don’t. Sometimes, they become friends, even mates.  Hounds can be trained to run down a coyote, but sometimes, the coyote and the dog become lovers in the forest.

Social, opportunistic predators that exist at this level of success are going to be a series of contradictions. Dogs, wolves, and coyotes certainly are. And so are we.

It is what we both do. And always will.

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