Tag: origin of dogs

New insight into the history of our dogs.

Our dogs have come a very long way.

I feel a little guilty at just dropping this full article in your path, and running away, so to speak, but yesterday was one of those days where Jean and I were “full on” for most of the day, and then out from the house from 4pm onwards.

It doesn’t lessen the interest, in my humble opinion, of this essay, that was recently published by The Conversation, and is republished within their terms.

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New DNA analysis says your pooch’s ancestors were Central Asian wolves

October 20, 2015

Author: Laura Shannon, Postdoctoral Research Associate in Biological Sciences, Cornell University

Dogs’ origin story goes something like this: sometime between 16,000 and 30,000 years ago, there were some stressed-out hungry wolves whose hunting territory had been encroached upon by humans. Luckily, these wolves were resourceful and they noticed human beings have a tendency to leave delicious things lying around. Scavenging leftovers seemed significantly easier than going out and hunting, so they hung around the people.

Wolves make unnerving neighbors. However, some are less unnerving than others. The humans were a lot more inclined to tolerate the proximity of less aggressive, more people-oriented wolves. As an added bonus, other predators are less likely to harass you when you are surrounded by wolves. So the people and the nicest wolves came to an agreement – the people tolerated and fed the tamest and most helpful wolves.

Smart, tame wolves have smarter, tamer wolf cubs, and so over time the wolves became more and more pleasant to have around. Obviously, friendly, helpful wolves hanging around people and eating leftovers aren’t really wolves; we have a word for those things – they’re dogs.

That’s biologists’ reasonable guess for how dogs came about. We have some idea when it all happened, but it’s been harder to figure out where. Who first took in scavenging gray wolves and turned them into dogs?

Dogs still know a good thing when they see it – warmth and food with people ‘round the campfire. Camping image via www.shutterstock.com.
Dogs still know a good thing when they see it – warmth and food with people ‘round the campfire. Camping image via http://www.shutterstock.com.

Investigating this wheredunit

Scientists have looked at DNA inherited exclusively from the mother (called mitochondrial) and DNA inherited exclusively from the father (the Y-chromosome) and suggested that dogs were first domesticated in China, south of the Yangtze River.

However, the oldest dog bones anyone has found are from the other end of Eurasia, all the way in Northern Europe. Furthermore, the mitochondria of modern dogs are closely related to the mitochondria of ancient European wolves.

Finally, Middle Eastern wolves share the most genetic sequences with today’s dogs, which makes it seem like maybe Middle Eastern wolves are the ancestral wolf population.

All these threads of evidence broadly agree that dogs are from somewhere in Eurasia. But my colleagues and I wanted to narrow that down a bit – and to do that, we decided we needed DNA from as many dogs as possible for our new study.

Team members sampling a village dog in the Pacific Islands. Adam Boyko, CC BY-ND
Team members sampling a village dog in the Pacific Islands. Adam Boyko, CC BY-ND

Modern dogs cover the globe

Dogs are found almost everywhere people are, and over time we have bred them to do everything from guarding livestock to going fishing. The breeds we’ve created come in many shapes and sizes, ranging from tiny Chihuahuas to giant Great Danes. The vast majority of these breeds are less than 200 years old and come from Europe. But these purebred dogs or even mixes of these breed dogs are the minority of dogs on the planet.

Most dogs are free-ranging village dogs, which live around and among people but aren’t necessarily what you’d think of as pets. You can learn more about ancient dogs by studying these village dogs (as compared to studying breed dogs) because village dogs have more genetic diversity; the number of different versions of the same genes in village dogs is higher than it is in breed dogs.

All dogs were formed from a select group of wolves, and therefore have a subset of the genetic diversity found in wolves. But breeds were formed from a subset of dogs so they have only a further subset of the diversity found in dogs.

In the cradle of dogkind? Coss and Johanna, CC BY-NC
In the cradle of dogkind? Coss and Johanna, CC BY-NC

Tracing the trail through DNA sequences

Members of our lab traveled to collect blood or spit from dogs in a variety of locales, and collaborators sent us fluids from places to which we didn’t manage to travel. Village dogs are fairly easy to find for researchers carrying food. In total, we extracted DNA from the fluids of 549 dogs from 38 countries spanning the majority of the globe as well as 4,676 purebred dogs. Our lab at Cornell is conveniently located in the same building as a veterinary hospital, so most of our purebred dogs were patients.

Once we had our samples, we then determined each dog’s genotype at about 180,000 distinct points in the genome. This is the largest data set anyone has used to address the question of dog origins so far.

We were looking for a very specific pattern of historical genetic diversity. When a select group of wolves became dogs, those dogs contained only the genetic diversity present in that subset of wolves. When people took some of the dogs and moved on to new regions of the globe, or traded dogs with people in other regions, they took only a subset of the total dogs, and by extension a subset of the total diversity.

Therefore, we expect the original population of dogs to be the most diverse. There would be a gradient of decreasing diversity in all populations as they move away from the center of origin.

And this is the pattern we observed when we compared the genetics of dogs from different populations. Dogs from Central Asia, Mongolia and Nepal are the most diverse, with genomes that correspond to the early, original variation in the population right after domestication happened. When we look at the same DNA markers in dogs from neighboring regions, diversity decreases. It decreases further corresponding to the location’s increasing distance from Central Asia. This is the pattern we would expect if the people who first took in scavenging gray wolves and turned them into dogs were located in Central Asia.

Even dogs we sampled in the Pacific Islands traced their forebears back to Central Asia. Adam Boyko, CC BY-ND
Even dogs we sampled in the Pacific Islands traced their forebears back to Central Asia. Adam Boyko, CC BY-ND

Looking at the largest data set of dogs amassed so far, we observe a very clear signal that most dogs alive today descended from dogs in Central Asia. However, we only looked at dogs alive right now. We have no information about historical populations of dogs that have no living descendants. Furthermore, the patterns of diversity we observe are reflective of the origins of dogs but also of everything that has happened to dog populations since domestication.

Other research groups are extracting DNA from bones of ancient dogs, and these sequences will provide exciting new insights from time points closer to domestication. However, ancient DNA studies are limited by the availability of ancient dog bones – which is affected by many factors other than the distribution of historic populations; for instance, some environments are more conducive to the preservation of bone and DNA than others, some regions have been more extensively investigated by archaeologists than others, and so on. If we see similar patterns in ancient and modern dogs, that will add clarity to the history of dogs and the people who love them.

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 Ultimately, it doesn’t matter one hoot, in a non-scientific sense, from where our dogs are descended. Just that they did evolve.

For human life without our dogs would be unthinkable.

The origins of the dog

Dogs and humans go back even further than previously thought.

Humans and dogs were constant companions well before our ancestors settled in villages and started growing crops 10,000 years ago …

I have no doubt that thousands of dog owners all around the world must be enthralled by the way that dogs relate to us and, in turn, how we humans relate to dogs. More than once a day, one of our dogs will do something that has me and Jean marvelling at their way of living so close to us.

Then when one starts to reflect on how long dogs and humans have been together, perhaps it could be seen as the direct result of that length of relationship.

Now there’s nothing new in me writing this, after all the home page of Learning from Dogs states:

Yet they have been part of man’s world for an unimaginable time, at least 30,000 years. That makes the domesticated dog the longest animal companion to man, by far!

Back in May the website Livescience published an article that revealed more about the length of our relationship with dogs. This is how it opened:

Ancient Wolf DNA Could Solve Dog Origin Mystery

by Becky Oskin, Senior Writer

Humans and dogs were constant companions well before our ancestors settled in villages and started growing crops 10,000 years ago, a new study suggests.

Genetic evidence from an ancient wolf bone discovered lying on the tundra in Siberia’s Taimyr Peninsula reveals that wolves and dogs split from their common ancestor at least 27,000 years ago. “Although separation isn’t the same as domestication, this opens up the possibility that domestication occurred much earlier than we thought before,” said lead study author Pontus Skoglund, who studies ancient DNA at Harvard Medical School and the Broad Institute in Massachusetts. Previously, scientists had pegged the wolf-dog split at no earlier than 16,000 years ago.

The Livescience article referred to results that were published in the journal Current Biology on May 21st this year. One needs a subscription to read the full report but here is their summary:

The origin of domestic dogs is poorly understood [ 1–15 ], with suggested evidence of dog-like features in fossils that predate the Last Glacial Maximum [ 6, 9, 10, 14, 16 ] conflicting with genetic estimates of a more recent divergence between dogs and worldwide wolf populations [ 13, 15, 17–19 ]. Here, we present a draft genome sequence from a 35,000-year-old wolf from the Taimyr Peninsula in northern Siberia. We find that this individual belonged to a population that diverged from the common ancestor of present-day wolves and dogs very close in time to the appearance of the domestic dog lineage. We use the directly dated ancient wolf genome to recalibrate the molecular timescale of wolves and dogs and find that the mutation rate is substantially slower than assumed by most previous studies, suggesting that the ancestors of dogs were separated from present-day wolves before the Last Glacial Maximum. We also find evidence of introgression from the archaic Taimyr wolf lineage into present-day dog breeds from northeast Siberia and Greenland, contributing between 1.4% and 27.3% of their ancestry. This demonstrates that the ancestry of present-day dogs is derived from multiple regional wolf populations.

That summary page also includes the following Graphical Abstract:

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I don’t have permission to republish the Livescience article in full but would like to offer the closing paragraphs of this fascinating report.

“It is a very well-done paper,” Perry [George Perry, an expert in ancient DNA at Pennsylvania State University] told Live Science. “This topic is a critical one for our understanding of human evolution and human-environment interactions in the Paleolithic. Partnership with early dogs may have facilitated more efficient hunting strategies.”

If dogs first befriended hunter-gatherers, rather than farmers, then perhaps the animals helped with hunting or keeping other carnivores away. For instance, an author of a new book claims humans and dogs teamed up to drive Neanderthals to extinction. Skoglund also suggested the Siberian husky followed nomads across the Bering Land Bridge, picking up wolf DNA along the way.

“It might have been beneficial for them to absorb genes that were adapted to this high Arctic environment,” Skoglund said.

This is the first wolf genome from the Pleistocene, and more ancient DNA from prehistoric fossils could provide further insights into the relationship between wolves, dogs and humans, the researchers said.

Yes, our dogs have been part of man’s world for an unimaginable time – and Jean and I, as with tens of thousands of others, can’t imagine a world without dogs.

This is the dog!

More close to man for more years than one could ever imagine.

A week ago, there was an article on Learning from Dogs entitled What is the dog? It was primarily based on the work of Dr. George Johnson; his details are here.

Anyway, last Thursday Pete N who is incredibly helpful in passing me items of interest, passed me a link to a series of videos that come under the collective name of Dogs Decoded.  They were on the website Top Documentary Films itself an interesting site.

It looks as though the videos are due to be released as a single film later on this year, as this link suggests.  Here’s how the three videos are introduced.

Dogs Decoded reveals the science behind the remarkable bond between humans and their dogs and investigates new discoveries in genetics that are illuminating the origin of dogs – with surprising implications for the evolution of human culture.

Other research is proving what dog lovers have suspected all along; dogs have an uncanny ability to read and respond to human emotions.

Humans, in turn, respond to dogs with the same hormone responsible for bonding mothers to their babies. How did this incredible relationship between humans and dogs come to be? And how can dogs, so closely related to fearsome wild wolves, behave so differently?

No more from me.  Just find a quiet corner and watch the three videos by clicking on each link in turn.  They will blow your mind.

Dogs Decoded (1/3)

Dogs Decoded (2/3)

Dogs Decoded (3/3)