Canis lupus hominis

Mark Derr takes on the big controversy on the origins of the domestic dog.

The pro-Southeast Asian and southern China  origins theorists have some conceptual problems:

A persistent bias in all these genetic analysis the geneticists are running assumes that the highest genetic diversity is found at a point of origin; indeed, the statistical analysis they use is based on that assumption. Another built-in bias assumes that an expanding population radiated out evenly from the place of origin.

Both assumptions have been shown to be inaccurate, but they persist in part because statistically they must and in part because the results are what the researchers want to prove their point. They do not.

For all we currently know the founding dog population–or its descendants–could have been decimated by war, disease, or the influx of a few favored dogs–or masses of dogs. Mitochondrial diversity can be increased by preferential keeping of breeding of females for food production, as was apparently done in the Area South of the Yangtze River. can also increase through expansion in an environment where it is relatively isolated from large-scale infusions of fresh blood that might overwhelm the native stock.

The real problem is that there is a desire to find that dogs originated in one place. I don’t know where this comes from. It might be  unintentionally theological– the quest for a secular and non-mythological Garden of Eden.

But as we’ve seen with many different domestic species– those that don’t have nearly as long an association with people– that most have evidence of at least two or more domestication events. Pigs were domesticated in the Near East and China.  We have evidence of early horse domestication in Saudi Arabia, the Ukraine, Russia, and Kazakhstan.  Cattle have two confirmed domestications– as in they were domesticated from the Eurasian aurochs in the Middle East and from the Indian aurochs in the Indus Valley. However, the Indus Valley aurochs was totally absorbed into the domesticated indicus cattle population. There is also evidence that European aurochsen bulls contributed to European taurine cattle that were derived from the Middle Eastern aurochs.

I don’t know why we would be so shocked to find that dogs have a similar history, but dog domestication is one that took place over a much longer time period and over virtually the entire continent of Eurasia.  Over this vast time and place, lineages have died out, and because both dogs and wolves can be quite mobile, lineages from one region can easily be transmitted to another.

Because of these reasons, we need to be very careful about using mtDNA and y-chromosome studies to tell us where the dog came from.

These studies are looking at only a tiny part of the genome. Even if they are including hundreds of samples, you’re still not getting a very good picture. Granted, the nuclear DNA studies that Wayne and the UCLA team have performed are also looking at just at tiny fraction of the genome,  but they are looking at a whole lot more of the genome than mtDNA and y-chromosomes.  The number of individuals in these samples may be significantly lower than the mtDNA and y-chromosome studies, but they are looking at each individual sample much more clearly.

They are being much more precise in what they are measuring, while the East Asian theorists are just looking at a large n. But only a tiny part of that large n.

It’s like looking a truckload of twigs, when you should be looking at a truckload of logs.