Dogs – perhaps the most popular domestic companion across the world – have intrigued scientists with their evolutionary history for as long as we’ve called dog man’s best friend – which, a new study says, may be longer than we ever thought. Comparison studies between dogs and their closest wild relatives, wolves, have been done to pinpoint the exact time when and where dogs became genetically independent. These genetic differences evolved into differing body shapes and key behavioral differences that allowed dogs to be domesticated.
Previous analysis of fragments of dog and dog relative DNA pointed to the Middle East as the geographic origin of the first dogs. A recent study released in Nature Communications is now pointing instead to an origination from East Asia, specifically, southern China. Lead authors Guo-dong Wang & Weiwei Zhai sequenced not just fragments of DNA, but whole genomes of dogs from various geographic regions. Tracking mutations between wolf and dog genomes allowed the international research team scientists to specifically show when dogs and wolves became separate, individual groups. Wang et al. estimate that the split occurred around 32,000 years ago.
However, there are many who do not agree with the conclusion that southern China was where dogs first became domesticated. Dr. Robert Wayne of the University of California, Los Angeles has a different conclusion based on genetic samples taken from 18 fossil dogs from across the globe. These samples were compared to numerous wolf and modern dog samples of genetic material. “It’s a simple story, and the story is they were domesticated in Europe,” says Dr. Beth Shapiro, a collaborator of Dr. Wayne from the University of California, Santa Cruz.
Dr. Wayne and Dr. Shapiro estimate that dogs and wolves branched off from each other between 18,000 and 30,000 years ago. They believe that the shift in behavior that slowly led to the evolution of dogs as an independent species was due to the benefits of being around humans of the time. Northern Europe was home to big game like horses, mammoths, and other animals that would gain the attention of ancient human hunters. After the kill, it was normal for humans to remove the parts of the animal that would be used (like the meat, hide, and some bones) and leave the rest of the carcass. Wolves were able to feed themselves on what the humans left behind and this slowly evolved into an innate behavior.
Scientists continue to sample and sequence DNA from fossil and modern dogs and wolves. As more data is collected it becomes more likely that the time and location of differentiation will finally be made clear.
Source: Wang, G. D., Zhai, W., Yang, H. C., Fan, R. X., Cao, X., Zhong, L., … & Zhang, Y. P. (2013). The genomics of selection in dogs and the parallel evolution between dogs and humans. Nature communications, 4, 1860.