though all these canid species can interbreed. But his estimated date for the origin of dogs as a separate population—135,000 years ago—seemed far too early to archaeologists. The oldest dog bone found so far, in Germany, is 14,000 years old, with other dogs 12,000 years old known from Israel. A much more plausible date emerged from a subsequent survey by one of Wayne's colleagues, Peter Savolainen, now at the Royal Institute of Technology in Stockholm. Savolainen collected mitochondrial DNA, asking dog fanciers from all over the world to send him hairs from their breeds. With samples from 654 dogs from Europe, Asia, Africa and America, and 38 Old World wolves, he was able to pinpoint the likeliest region where dogs were domesticated as being somewhere in East Asia, even though the earliest known dog remains occur in the West. This is because there is more variability in the DNA of East Asian dogs than anywhere else in the world, and a rule of thumb in genetics is that the region of a species' greatest diversity is its place of origin. Almost all the dogs in Savolainen's sample fell into three main clusters, suggesting either that they had been domesticated independently three times or that three related wolves from the same litter or pack had been domesticated at the same time and place. Savolainen favors the latter interpretation because it gives a more plausible date for the domestication event—15,000 years ago. (The alternative case of three separate domestica tions implies a date of 40,000 years ago. But an invention as useful as the dog would probably have spread
Was this article helpful?