text: The United States is home to an estimated 70 to 80 million pet dogs, making up 37 to 47 percent of all American households. We affectionately call them man’s best friend, and they are, in fact, humankind’s oldest “friend” in the animal kingdom. Canis familiaris, the domestic dog, was the first species to be domesticated by humans from Eurasian gray wolves at least 15,000 years ago. What is largely unknown, however, is where. A new genomic study, published today in the Proceedings of the National Academy of Sciences, offers up strong evidence that domesticated dogs originated in Central Asia, around modern day Nepal and Mongolia. 
   
   Previous genetic studies of dog lineages have concluded that domestication occurred in Southern China around 16,500 years ago, but the earliest archaeological evidence of domesticated canines is found in Europe and Siberia. All of this contrasting evidence has understandably created not a small amount of debate, but one thing that can be agreed upon is that all dogs came from Eurasian gray wolves at least 15,000 years ago. One key factor was largely neglected in previous studies, however. 
   
   Canis familiaris can be broken down into essentially two main groups: One of pure breeds and mixed breeds—about 400 types—that make up most American pets and another, much larger group of free-roaming and breeding populations known simply as “village dogs.” Despite the wide variation in outward physical appearance, pure breeds are not genetically very diverse, because they come from such small, controlled gene pools. (Remember, as crazy as it seems, a Chihuahua and a St. Bernard are still the same species.) Most modern breeds, in fact, are only about 200 years old (though artificial selection by humans on dogs has been occurring for thousands of years). The majority of dogs, along with their genetic diversity, fall in the group of “village dogs,” and have much older lineages than the pure breeds. It makes them particularly important when studying dog evolution. Adam Boyko, of Cornell University, and his colleagues factored this group of dogs heavily into their study. 
   
   Boyko’s team analyzed 185,800 genetic markers in 5,392 dogs, including 549 village dogs from 38 countries, making their study the largest ever of worldwide canine genetic diversity. They found that genetic diversity is highest in Central Asia, specifically Nepal and Mongolia. Genetic diversity then fans out like ripples in a pool, with areas like Afghanistan, Egypt, India, and Vietnam—all ringing around the possible center of origin in Central Asia—having the next highest levels and so on. “It mirrors what we see in humans and how they spread out of East Africa,” says Boyko. 
   
   Dogs studied in geographic regions farther away, like the South Pacific and Americas were almost exclusively of European origin. This complicates things a bit, but the reason for that is likely the spread of modern Western culture and the appeal of pure breeds. “Everybody wants a golden retriever,” says Boyko. Perhaps one of the reasons village dogs with more indigenous traits have not been overcome by foreign gene flow in Central Asia is because they originated there and have large populations. They also might be better adapted to that environment, notes Boyko. 
   
   “At Bichon Frise running wild in Mongolia is not going to do very well,” he says, “But if Ulaanbaatar (the capital) became the next biggest city in Asia, then perhaps some Bichons would do alright there," and mix with the indigenous village dogs. ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| Dogs became man’s best friends somewhere in central Asia close to Nepal and Mongolia, according to the largest genetic study yet. The work looked at DNA from thousands of living dogs to piece together their ancestry and geographical origins. 
   
   “This is the first global study of genomic patterns of dog diversity,” says Adam Boyko of Cornell University in Ithaca, New York, who led the team. “We find a clear pattern of genetic diversity focused on central Asia, suggesting the first domesticated dogs came from this region.” 
   
   That departs from earlier studies that pinpointed Europe as where dogs were domesticated, although more recent work puts the location in southern China, just 1000 kilometres from the area Boyko’s team proposes. 
   
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   The team broke new ground by analysing DNA samples from so-called “village dogs”, which have lived alongside humans throughout the world since dogs first evolved from wolves and were domesticated around 15,000 years ago. “Although they associate with humans, village dogs are more or less expected to make it on their own,” says Boyko. 
   
   Authentic signature 
   
   “They are very different from pure-bred dogs genetically because they are free-breeding, so in a genetic sense, they are a natural population.” Village dogs therefore carry a more authentic genetic signature of original dog populations than the modern-day breeds created in the past 200 years, mainly in Europe. 
   
   Boyko’s team took DNA samples from 549 village dogs in 38 countries all over the globe. They also took samples from 4676 pure-bred “modern” dogs of 161 breeds, many of European origin. 
   
   To further improve the reliability of the analysis, the team broadened the amount of DNA examined to include chromosomes inherited from both parents. Previous studies had relied mainly on mitochondrial DNA transmitted through the female line, or DNA from male sex chromosomes. 
   
   By analysing 185,805 genetic markers, Boyko’s team traced how all the animals were related, and from that how they had spread around the world. This essentially gave them a trail back to “founder” dogs in Nepal and Mongolia. 
   
   The analysis also revealed that following domestication, village dogs rapidly fanned out to other areas of Asia, particularly India and south-west and east Asia. 
   
   Scavenging 
   
   Boyko’s team speculates that hunter-gatherers in central Asia domesticated dogs from grey wolves. A combination of increasing human population density, better hunting methods and climate change may have reduced the availability of prey and pushed some wolves towards scavenging, which favoured tameness and smaller size. This would in turn have reduced their hunting prowess further, setting them on the path to domestication. 
   
   Other researchers have welcomed the tracing of domestication to the neighbourhood of central Asia, although some dispute the precise site. 
   
   “They are actually putting the origin very close to where we put it, just 1000 kilometres away in parts of Asia south of the Yangtze river,” says Peter Savolainen of the Royal Institute of Technology in Solna, Sweden. “So I would say the consensus pointing to south and east rather than central Asia is quite clear.” 
   
   Savolainen compliments the thoroughness of the study, but says that what is lacking is DNA from southern China, where he thinks dogs originated. “Since they don’t have a single sample from south China, they haven’t falsified [my] theory,” he says. 
   
   Olaf Thalmann at Uppsala University in Sweden praises the scale of the study, and says its conclusion is reasonable. “We know that this region was pivotal for ancient trade, and it seems plausible that animals followed the trading routes and thus increased the local diversity,” he says. 
   
   But Thalmann doubts that the study is the final word on where dogs were tamed, because the DNA comes only from animals living today. “I’m convinced the only way to shed further light on the topic is by analysing ancient remains,” he says. A consortium led by Greger Larson of the University of Oxford is now looking to doing just that. 
   
   Larson says Boyko’s result is important because it reaches a clear conclusion that can be tested further. “We are excited to be working with Boyko’s group and others,” he says. 
   
   “Having collected more than 1500 ancient dogs and wolves over the past few years, our lab has begun our next-generation sequencing effort.” The genetic data will then be compared with morphological data from more than 4000 specimens going right back into the late Pleistocene, he says. 
   
   Journal reference: PNAS, DOI: 10.1073/pnas.1516215112 
   
   (Image credit: FLPA/REX Shutterstock) 
   
   Read more: “Man’s best friends: How animals made us human“ ||||| Image copyright Getty Images Image caption Dogs may have become man's best friend in Central Asia, according to the study 
   
   Today's dogs can trace their origins to Central Asia, according to one of the most comprehensive genetic surveys yet. 
   
   Dogs are the most diverse animal on the planet - a legacy of thousands of years of selective breeding by humans. 
   
   But they derive from wild wolves that were gradually tamed and inducted into human hunting groups - perhaps near Mongolia or Nepal. 
   
   The findings come from an analysis of DNA from thousands of pooches, and are published in PNAS journal. 
   
   Cornell University's Dr Adam Boyko and his colleagues studied 4,676 purebred dogs from recognised breeds, as well as 549 "village dogs" - free-ranging animals that live around human settlements. 
   
   They hitched themselves to us, which was a pretty good gamble as it turned out Dr Adam Boyko, Cornell University 
   
   This latter group are the least studied, yet represent a crucial piece in the picture of modern dog diversity. 
   
   "The fact that we looked at so many village dogs from so many different regions, we were able to narrow in on the patterns of diversity in these indigenous dogs," Dr Boyko told BBC News. 
   
   Dog domestication is the kind of event that could have taken place independently in different corners of the globe. But the DNA of modern pooches doesn't provide any support for this idea. 
   
   "We looked exclusively to see if there was evidence of multiple domestication events. And like every other group that's looked for that, we found no evidence of it," said Dr Boyko. 
   
   "It looks like there's a single origin, although there are clearly situations where there has been... a little bit of gene flow between wolves and dogs post-domestication." 
   
   Image copyright Getty Images Image caption Dog ownership is growing in popularity across many parts of Asia 
   
   Image copyright AFP Image caption A Tibetan mastiff dog is seen at a show in China's northern Hebei province 
   
   Confusing picture 
   
   The researchers studied genes that are located close to one another on dog chromosomes. The patterns of these closely linked genetic markers allowed the team to pinpoint the domestication event to Central Asia. 
   
   But several other teams have tackled the same problem, and have come up with widely differing results. 
   
   Previous studies have variously hinted at an origin for dogs in the Middle East - perhaps scavenging the food waste of early farmers - in East Asia, and in Europe. 
   
   The latest results are unlikely to resolve the argument, but Dr Boyko said that localising the origin of dogs could stimulate further research. One of these further lines of inquiry could be the analysis of ancient DNA from dog remains found at archaeological sites. 
   
   This tool could help support or refute hypotheses about the role of Central Asia and other regions in the domestication of "man's best friend". 
   
   Image copyright Getty Images Image caption DNA studies have shown that modern dogs descended from their wolf ancestors 
   
   Dr Peter Savolainen, associate professor at KTH - Royal Institute of Technology in Sweden, said the study had shown it was possible to find remote dog populations that had been unaffected by mixing with European varieties - a legacy of the era of colonisation. 
   
   But he suspects the origins of domestication lie in East Asia, perhaps in southern China. 
   
   "Mongolia is technically in East Asia and Nepal is in South Asia... only a thousand kilometres from South China," he told BBC News. 
   
   "So we have a consensus that the origin is somewhere in this general region. But one important thing is that they do not have a specimen from China, so if they had, what would that have shown?" 
   
   Most researchers agree that dogs have been around for at least 15,000 years. But the reasons for their emergence remain opaque. 
   
   "There's no doubt they were hanging around [hunting] camps and becoming gradually more attuned to human life. The question is what was the first step for why that was happening," said Dr Boyko. 
   
   "It's tempting to ask whether it was something to do with hunting. I think it's clear that scavenging by wolves on human kills [of large mammals] could have been the driving force. 
   
   He added that genetic changes in those wolves, that led to tameness, small body size and early age of first reproduction could have started the animals down an evolutionary course that was less compatible with a hunting lifestyle. 
   
   "They hitched themselves to us, which was a pretty good gamble as it turned out, because there are about a billion dogs in the world today and probably not even 10 million wolves." 
   
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target: – Your best pal may have come a long way to curl up at your feet: A new DNA study of more than 5,000 dogs from 38 countries finds they probably originated in Central Asia, or Mongolia and Nepal more specifically, at least 15,000 years ago, reports the BBC. Cornell researchers drew blood from 4,676 purebred dogs—making up 161 breeds typically created in the last 200 years—and 549 street dogs with older lineages to study chromosomes inherited from the male and female line, reports New Scientist. The data showed genetic diversity is highest in Central Asia, then in surrounding areas like Afghanistan, Egypt, India, and Vietnam, reports Popular Science. That suggests the most recent common ancestor of "all the dogs alive today" came from that region, says lead author Adam Boyko. "It mirrors what we see in humans and how they spread out of East Africa." It's possible some dogs were domesticated elsewhere but diversified in Central Asia. But "we found no evidence" of multiple domestication events, Boyko says. "It looks like there's a single origin," though there appears to have been "a little bit of gene flow between wolves and dogs post-domestication." Boyko's team suspects higher human population density, better hunting techniques, and climate change pushed gray wolves toward scavenging, which led to domestication. But as similar studies suggest dogs originated in the Middle East, East Asia, and Europe, some scientists are treating the results with caution. One tells the New York Times that only a study of ancient and modern DNA could provide definitive results. Among difficulties researchers faced: "We showed up in Puerto Rico at a fishing village and the dogs turned up their noses at roast beef sandwiches," says Boyko. "They were used to eating fish entrails." (Genetically, house cats are basically wild animals.)