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Tracing bloodlines for the roots of an age-old friendship

An international team hunt for the origins of dog domestication.
Performing a medical procedure on a live animal isn’t for a faint hearted researcher. So when a village dog in rural India bit Ryan Boyko’s thumb, he figured it was a small price to pay (although he got a tetanus shot to be safe) for the opportunity to explore some of the big questions of dog lovers — when and where did that special relationship between dog and human begin?
To answer these questions, Boyko and an international team of collaborators, led by his brother Professor Adam Boyko from Cornell University in Ithaca, New York, took on a project that would make most vets blanch: to collect blood from 549 village dogs across 38 countries.
The aim was to map the dogs’ genetic relationships and through that, trace the history of dog domestication. Boyko, the CEO of dog DNA testing company, Embark Veterinary Inc, wanted to know “what makes dogs dogs and to what extent does that help us understand what makes people people?”
Around the world
From Mongolia to India, and Nepal to the Congo, the Boyko brothers travelled from village to village, accompanied by a local collaborator or guide, knocking on doors and asking if the owners had a dog they could sample. “The owners are really interested, because everybody wants to know where their country’s dogs came from.” They found more than enough dog owners happy to take part. In areas where rabies is endemic, the team also offered a free rabies immunisation for the dogs.
But the project had its complexities. “Trying to explain the concept of centrifuge in Swahili at border crossings was kind of difficult,” says Adam Boyko.
How to take blood from a dog that had never been on a leash posed another quandary. The team considered sedating the animals to take the sample, from the cephalic vein in the front paw, but that presented its own logistical challenges. Travelling with a controlled substance such as a sedative across international borders isn’t ideal, Adam Boyko says. “Then ethically you need to stay with that dog until it’s back on its feet and able to defend itself from other dogs.”
The team decided to leash and muzzle the dogs, but that also had drawbacks. “When you a put a leash on them they flip out because they’ve never had a leash on them before, but amazingly they try to bite the leash — none of them have tried to bite the person holding the leash,” he says. “I’m not saying nobody got bit, but nobody got bit putting the leash on.”
Motley crew
While it would have been easier for the research team to study pure-bred dogs, which are likely to be more accustomed to human touch, rather than village dogs, that would have missed the bigger picture.
“If you’re trying to do the timing [of domestication] just based on pure-bred dogs, then this strong artificial selection and recent inbreeding can really skew your estimates,” Adam Boyko says.
In the end, the DNA analysis of village dogs revealed the greatest genetic diversity in central Asia, suggesting this was the region where dogs and humans first found common ground. The result, published in the Proceedings of the National Academy of Sciences in August 2015, contrasts with earlier evidence suggesting domestication originated in south-east Asia.
Adam Boyko said the researchers were so surprised by the finding they did more detailed simulation modelling to determine if something had skewed their results, but found nothing.
They are now planning a more detailed genetic survey of Asian village dogs to build a clearer picture of where and when that domestic relationship first developed.
By Bianca Nogrady

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