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The Debate on Canine Domestication
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One reason for the disparities, according to Oxford’s visionary evolutionary biologist Greger Larson, who was a part of a team that successfully mapped the origin of the pig, is that scientists studying the dog are not including enough ancient DNA in their studies.

Larson and colleague Keith Dobney, an archaeologist at the University of Aberdeen, had the idea to bring together all the evidence collected to date, find ancient canid specimens from museums, apply state-of-the-art technology and create a database bigger than anything produced before. All they had to do was convince scientists to agree to work together.

Fortunately for canine genetics, Larson was able to sell the idea that more cooperation and collaboration improves the outcome. As chief mediator and conciliator, and supported by substantial funding, he has persuaded more than 50 influential canine evolutionary scientists to join the project. Team members include archaeologists, paleobiologists, anthropologists, zooarchaeologists, paleogeologists and others.

The purpose of the study, which began in 2013 and is slated to wrap up this year, is to combine ancient DNA analysis and geometric morphometric techniques and apply them to archaeological canid remains. This, he suggests, will directly address where, when and how many times dogs were domesticated.

Geometric morphometrics, the study of form in two or three dimensions, is a powerful new way to visually quantify evolutionary relationships. It does this by correlating thousands of geometric points that identify exact places on bones—specifically, points of evolutionary significance that differ between very closely related animals such as the wolf and the dog.

Using a special camera, researchers take hundreds of 360-degree photographs. Software then transfers the pictures to a three-dimensional computerized image that emphasizes a set of tightly defined, very specific points on each bone. The process results in holographic- like images that show domestication in progress through space and time, much like a movie.

Additionally, scientists are isolating and examining ancient DNA collected from museum specimens, looking for changes in the degree of genetic diversity over long periods. This will provide a comprehensive overview of the wolf-to-dog transition from the beginning to the present.

No individual genetic fragment of DNA says This is a wolf or This is a dog. Rather, scientists tease the two apart by looking at strands of DNA and identifying and measuring similarities and differences. As differences become more extreme, the separation between wolf, proto-dog and, finally, dog is suggested.

The team hopes to isolate genetic fragments that can be linked to minor changes in the geometric morphometricimaged samples. Combining the two techniques will tell a deeper, more layered and detailed story about canine domestication.

Larson expects to analyze up to 7,000 specimens representing wolves, incipient canids and domestic dogs. “We’re taking samples from all over the world, sources in not only museums but from private collections, too. Curators are very agreeable when we ask for permission, and they’re usually very happy to have us take photos and DNA samples. They help us, and in turn, we provide more information for their collection.”

While Larson is enthusiastically optimistic about the outcome of this unprecedented project, some scientists not affiliated with the study think the findings will only add to the existing mishmash of conflicting hypotheses. But that’s how science works: come up with an answer and you invariably end up with a lot more questions.

The ongoing search to understand where, when and how many times dogs were domesticated continues to be a topic of active scholarly exploration. Besides the millions of dog lovers who are curious about the roots of our affectionate and unusual cross-species relationship, substantial scientific issues are at stake, issues that may profoundly alter the future of evolutionary theory.

Read about new developments.

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Jane Brackman, PhD, is an authority on the cultural history of canine domestication and the author of two books on pets in 19th-century America. See her new pup, Barkley, and watch him grow on her blog.

doctorbarkman.blogspot.com

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