August 06, 2009

Dog domestication history reconsidered

There are several important lessons from this new study:
  1. We are back to square one when it comes to the origin of domestic dogs, as the discovery of similar genetic diversity in African and Asian dogs casts doubt on the Asian origin theory
  2. In general, making inferences of gene flow based on diversity measures is very sensitive to sampling.
  3. Greater genetic diversity may be the result of either greater antiquity or admixture; if an extra-terrestrial scientist, knowing nothing about human history, studied the genetic diversity of humans, he would probably conclude that they originated in the Americas, if he overlooked the possibility that the highly diverse population of the New World is the result of very recent admixture and settlement.
  4. Domestication resulting from artificial selection leads to loss of genetic diversity. Thus, differences in genetic diversity may be due to differences in the intensity of domestication-related changes, rather than due to differences in antiquity.

One generally does not speak of humans as "domesticated" or "wild", but, nonetheless, humans vary greatly in the way they reproduce. In some cases, choice of marriage partner is a complex long-term process of selection from alternatives, while in others it is a shorter more "natural" one. It would be a great idea to study the social correlates of human genetic diversity, rather than assume that all humans are at a similar level of self-domestication and thus differences between them are simply the product of their respective antiquity.

PNAS doi:10.1073/pnas.0902129106

Complex population structure in African village dogs and its implications for inferring dog domestication history

Adam R. Boyko et al.


High genetic diversity of East Asian village dogs has recently been used to argue for an East Asian origin of the domestic dog. However, global village dog genetic diversity and the extent to which semiferal village dogs represent distinct, indigenous populations instead of admixtures of various dog breeds has not been quantified. Understanding these issues is critical to properly reconstructing the timing, number, and locations of dog domestication. To address these questions, we sampled 318 village dogs from 7 regions in Egypt, Uganda, and Namibia, measuring genetic diversity >680 bp of the mitochondrial D-loop, 300 SNPs, and 89 microsatellite markers. We also analyzed breed dogs, including putatively African breeds (Afghan hounds, Basenjis, Pharaoh hounds, Rhodesian ridgebacks, and Salukis), Puerto Rican street dogs, and mixed breed dogs from the United States. Village dogs from most African regions appear genetically distinct from non-native breed and mixed-breed dogs, although some individuals cluster genetically with Puerto Rican dogs or United States breed mixes instead of with neighboring village dogs. Thus, African village dogs are a mosaic of indigenous dogs descended from early migrants to Africa, and non-native, breed-admixed individuals. Among putatively African breeds, Pharaoh hounds, and Rhodesian ridgebacks clustered with non-native rather than indigenous African dogs, suggesting they have predominantly non-African origins. Surprisingly, we find similar mtDNA haplotype diversity in African and East Asian village dogs, potentially calling into question the hypothesis of an East Asian origin for dog domestication.


1 comment:

eurologist said...

Depends on what you mean by "Asian". Given the early appearance of domesticated wolves/dogs in the European archeological record, I never believed in an East-Asian origin. However, their descent from Eurasion wolves is not called into question.

The new study shows that there must have been a large population of early domesticated dogs, spreading quickly via relatively heavy populations of humans. An origin in the Northern India/Pakistan/Afghanistan/ and other mid-northern XXX-stan countries area satisfies both, and also would explain the rapid spread to Europe.