Saturday, September 12, 2009

Single origin for domesticated dog in Southeast Asia and South China

At the end of this article is the abstract of a new study suggesting a single origin for dogs in Asia south of the Yangtze River. The entire article is available for free viewing and downloading online by following the Open Access link below.

The study uses the principle of "greatest diversity" in determining the origin of the domesticated dog. The idea again is that dogs migrating away from the place of origin carry some but not all of the genetic types found within the species. Therefore, nearly all the dogs outside of "ASY," which stands for "Asia south of the Yangtze," i.,e. South China and Southeast Asia, originated from a subset of the total haplogroups found in ASY. And there were many unique haplotypes found only in ASY. Only in this region were all 10 major haplogroups found and this number decreases as one moves further away through Eurasia with the lowest total of four haplogroups found in Europe.

Interestingly of all the geographic areas tested, the Southeast Asian sample had the highest genetic diversity at 0.9526 followed by South China at 0.9486. The exact samples from these regions are:

South China:
Guangdong (n=14), Guangxi (n=35), Hunan (n=54), Guizhou (n=57), Jiangxi (n=46), Yunnan (n=75)

Southeast Asia
Thailand (n=41), Vietnam (n=11), Cambodia (n=7)

What is apparent is that with the exception of northern Yunnan, the wolf is not present in any of these areas in modern times. At one time, it was assumed that the wolf must have extended over all this region and further because of the existence of the dingo in Australia.

The dingo was considered a wild dog, but modern research led by one of the supporting authors of the current study -- P. Savolainen -- suggests that the dingo is actually a descendant of the domesticated dog.

However, the dingo's behavior is very much like a wild dog suggesting that possibly it represents a mixture of wild and domesticated dogs. Multi-generational feral dogs generally depend on human settlement where they scavenge garbage heaps, beg for scraps, and, in some cases, prey on livestock. Most dingos, though, lived totally independent of human populations when they were first studied by Europeans.

Now the existence of similar "wild" dingos in Thailand and Sulawesi, and dingo-like feral dogs throughout much of Southeast Asia, is suggestive. If the original domesticated dog was often feral, as is the case in modern Southeast Asia, then interbreeding with wild wolves could have been commonplace.

Although wolf packs will attack dogs and other wolves that are strangers to the pack, when individuals break off from a pack to mate, they are much friendlier. It is known that wolves, for example, in the Americas will even sometimes mate with different species like the coyote.

So during the early domestication period, large packs of feral or semi-domesticated dogs may have bred with the wild dog, or wolf population. Eventually these mixed types would have developed into the wild-ranging dingo, or the wild populations wold merge with feral dog stocks. This could explain why the pure wolf is no longer found in Southeast Asia or most of South China.

Now when the domesticated dog moved out of ASY, it would have encountered different situations especially among pastoral peoples. These groups raise herds of free-ranging livestock, which are very vulnerable to predation by feral dogs. Thus, humans in these cultures would have taken greater measures to cull feral dog populations. Also, they probably trained dogs at an early age to guard herds and flocks against wolves, which would have helped prevent interbreeding between wolf and dog. Across many of the geographical areas bordering ASY, feral dog populations cannot survive to the same extent as in ASY. In these areas, dogs become more dependent on humans and the number of feral dogs decreases.

The authors suggest that the domesticated dog spread with agriculture, however, I think the archaeological record clearly contradicts this assertion. Dogs were diffused during the Mesolithic period, possibly when humans were first engaging in pastoralism, if we accept that the latter practice arose among hunter-gatherers. I wonder if there is any influence on the idea of dogs diffusing together with agriculture, that comes from the Chinese tradition of Panhu, the Dog-Man-God, which is sometimes interpreted as referring to the spread of the domesticated dog. I give my explanation of this myth and its relation to the spread of rice agriculture here and here.

Paul Kekai Manansala

Mol Biol Evol. 2009 Sep 1. [Epub ahead of print]
Click here to read

mtDNA Data Indicates a Single Origin for Dogs South of Yangtze River, less than 16,300 Years Ago, from Numerous Wolves.

State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.
There is no generally accepted picture of where, when, and how the domestic dog originated. Previous studies of mitochondrial DNA (mtDNA) have failed to establish the time and precise place of origin because of lack of phylogenetic resolution in the so far studied control region (CR), and inadequate sampling. We therefore analysed entire mitochondrial genomes for 169 dogs to obtain maximal phylogenetic resolution, and the CR for 1,543 dogs across the Old World for a comprehensive picture of geographical diversity. Hereby, a detailed picture of the origins of the dog can for the first time be suggested. We obtained evidence that the dog has a single origin in time and space, and an estimation of the time of origin, number of founders and approximate region, which also gives potential clues about the human culture involved. The analyses showed that dogs universally share a common homogenous gene pool containing 10 major haplogroups. However, the full range of genetic diversity, all 10 haplogroups, was found only in south-eastern Asia south of Yangtze River, and diversity decreased following a gradient across Eurasia, through 7 haplogroups in Central China, and 5 in North China and Southwest Asia, down to only 4 haplogroups in Europe. The mean sequence distance to ancestral haplotypes indicates an origin 5,400-16,300 years ago from at least 51 female wolf founders. These results indicate that the domestic dog originated in southern China less than 16,300 years ago, from several hundred wolves. The place and time coincide approximately with the origin of rice agriculture, suggesting that the dogs may have originated among sedentary hunter-gatherers or early farmers, and the numerous founders indicate that wolf taming was an important culture trait.


Related links

Dog as deity, ancestor and royal animal
Article: Dog reverence in Southeast Asia and Pacific
Interpretations of the Dog Husband Theme
Rajasuya , Sunahsepa and the Royal Dog
Deluge, Gourd, Dog Husband


Fleming, Peter; Laurie Corbett, Robert Harden, Peter Thomson (2001). Managing the Impacts of Dingoes and Other Wild Dogs. Commonwealth of Australia: Bureau of Rural Sciences.
Dingos (photo from Wikipedia)