"Long before it's in the papers"
November 26, 2011

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Debate heats up on dog origins: Middle East or Asia?

Nov. 26, 2011
Courtesy of KTH Royal Institute of Technology, 
UCLA and World Science staff

A group of re­search­ers claims to have con­firmed that the wolf an­ces­tors of to­day’s dogs can be traced to south­ern East Asia. But the find­ings contra­dict the­o­ries plac­ing the cra­dle of the ca­nine line in the Mid­dle East.

Pe­ter Savo­lain­en, a re­search­er in ev­o­lu­tion­ary ge­net­ics at Swe­den’s KTH Roy­al In­sti­tute of Tech­nol­o­gy, said a study re­leased Nov. 23 con­firms that a re­gion south of the Yang­tze Riv­er was the main and probably only ar­ea where hu­mans do­mes­ti­cat­ed wolves. 

Pho­to © Ya-ping Zhang

He and col­leagues used da­ta from the Y chro­mo­somes of dogs, which con­tain the genes for mak­ing a ma­le. Pre­vi­ous ev­i­dence in the same di­rec­tion came from mi­to­chon­drial DNA, a set of ma­ter­nally in­her­it­ed genes that lie in the power-producing com­part­ments of cells, Savo­lain­en said. “Taken to­geth­er, the two stud­ies pro­vide very strong ev­i­dence” that dogs orig­i­nat­ed in Asia south of the Yang­tze, which runs through China, he added.

But ar­chae­o­log­i­cal da­ta and a ge­net­ic study pub­lished March 17, 2010 in the jour­nal Na­ture sug­gest dogs come from the Mid­dle East. “Dogs seem to share more ge­net­ic si­m­i­lar­ity with Mid­dle East­ern gray wolves than with any oth­er wolf popula­t­ion world­wide,” said Rob­ert Wayne, a Uni­vers­ity of Cal­i­for­nia Los An­ge­les bi­ol­o­gist and sen­ior au­thor of that pa­per, last year. “Genome-wide anal­y­sis now di­rectly sug­gests a Mid­dle East or­i­gin for mod­ern dogs… a dom­i­nant pro­por­tion of mod­ern dogs’ an­ces­try de­rives from Mid­dle East­ern wolves.”

He added that “this is the same ar­ea where do­mes­tic cats and many of our live­stock orig­i­nat­ed and where ag­ri­cul­ture first de­vel­ope­d,” and that Asia seemed an un­likely source be­cause “there was nev­er a hint in the ar­chae­o­log­i­cal rec­ord that dogs evolved there.”

Savolainen dis­misses the Mid­dle East or­i­gins the­o­ry on grounds that “none of these stud­ies in­clud­ed sam­ples from” Asia south of the Yang­tze. Savo­lain­en and doc­toral stu­dent Mat­tias Os­kars­son worked with Chin­ese col­leagues to an­a­lyse DNA from male dogs around the world. About half the gene pool was un­iver­sally shared ever­ywhere in the world, while only the ASY re­gion had the en­tire range of ge­net­ic di­vers­ity, Savo­lain­en ex­plained. “This shows that gene pools in all oth­er re­gions of the world most probably or­i­ginate from the ASY re­gion,” he added. Their study is pub­lished in the re­search jour­nal Hered­ity.

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Some researchers say they have proved that the wolf ancestors of today’s dogs can be traced to southern East Asia. The findings run counter to theories placing the cradle of the canine line in the Middle East. Peter Savolainen, a researcher in evolutionary genetics at Sweden’s KTH Royal Institute of Technology, said a study released Nov. 23 confirms that a region south of the Yangtze River was the main and probably only area where humans domesticated wolves. He and colleagues used data from the Y chromosomes of dogs, which contain the genes for making a male. Previous evidence in the same direction came from mitochondrial DNA, a set of maternally inherited genes that lie in the power-producing compartments of cells, Savolainen said. “Taken together, the two studies provide very strong evidence” that dogs originated in southern East Asia, he added. But archaeological data and a genetic study published March 17, 2010 in the journal Nature suggest dogs come from the Middle East. “Dogs seem to share more genetic similarity with Middle Eastern gray wolves than with any other wolf population worldwide,” said Robert Wayne, a University of California Los Angeles biologist and senior author of that paper, last year. “Genome-wide analysis now directly suggests a Middle East origin for modern dogs… a dominant proportion of modern dogs’ ancestry derives from Middle Eastern wolves.” He added that “this is the same area where domestic cats and many of our livestock originated and where agriculture first developed,” and that Asia seemed an unlikely source because “there was never a hint in the archaeological record that dogs evolved there.” Savolainen dismisses the Middle East origins theory on grounds that “none of these studies included samples from” Asia south of the Yangtze. Savolainen and PhD student Mattias Oskarsson worked with Chinese colleagues to analyse DNA from male dogs around the world. Their study is published in the research journal Heredity. About half of the gene pool was universally shared everywhere in the world, while only the ASY region had the entire range of genetic diversity, Savolainen explained. “This shows that gene pools in all other regions of the world most probably originate from the ASY region,” he added.