Sunday, November 05, 2006

all dogs go to heaven


After numerous trips to the Lincoln Park Zoo the wolves were out. I had been more excited about seeing them than anything else (probably because they're so damn elusive) and when I finally got a look today I remembered that wolves are just freakin dogs! Oh yeah, I see those all the time. Although a passing ambulance did produce a chorus of yelps and howls; dogs rarely do anything that exciting anymore. So in honor of the decidedly uninteresting reminder of the ancestry of dogs, I thought I would do some investigation into the decidedly interesting into the ancestry of dogs.

Molecular systematics indicate that the domestic dog (Canis lupus familiaris) descends from one or more populations of wild wolves (Canis lupus). As reflected in the nomenclature, dogs are descended from the wolf and are able to interbreed with wolves.

The relationship between human and canine has deep roots. Wolf remains have been found in association with hominid remains dating from 400,000 years ago. Converging archaeological and genetic evidence indicate a time of domestication in the late Upper Paleolithic close to the Pleistocene/Holocene boundary, between 17,000 and 14,000 years ago. Fossil bone morphologies and genetic analysis of current and ancient dog and wolf populations have not yet been able to conclusively determine whether all dogs descend from a single domestication event, or whether dogs were domesticated independently in more than one location. Domesticated dogs may have interbred with local populations of wild wolves on several occasions (so-called introgression).

The earliest dog fossils, two crania from Russia and a mandible from Germany, date from 13,000 to 17,000 years ago. Their likely ancestor is the large northern Holarctic wolf, Canis lupus lupus. Remains of smaller dogs from Mesolithic (Natufian) cave deposits in the Middle East, dated to around 12,000 years ago, have been interpreted as descendants of a lighter Southwest Asian wolf, Canis lupus arabs. Rock art and skeletal remains indicate that by 14,000 years ago, dogs were present from North Africa across Eurasia to North America. Dog burials at the Mesolithic cemetery of Svaerdborg in Denmark suggest that in ancient Europe dogs were valued companions.

Genetic analyses have so far yielded divergent results. VilĂ , Savolainen, and colleagues (1997) concluded that dogs split off from wolves between 75,000 and 135,000 years ago, while a subsequent analysis by Savolainen et al. (2002) indicated a "common origin from a single gene pool for all dog populations" between 40,000 and 15,000 years ago in East Asia. Verginelli et al. (2005), however, suggest both sets of dates must be reevaluated in light of recent findings showing that poorly calibrated molecular clocks have systematically overestimated the age of geologically recent events. On balance, and in agreement with the archaeological evidence, 15,000 years ago is the most likely time for the wolf-dog divergence.

Verginelli examined ancient DNA evidence from five prehistoric Italian canids carbon-dated to between 15,000 and 3,000 years old, 341 wolves from several populations worldwide, and 547 purebred dogs. Their results indicate multiple independent origins of dogs and/or of frequent interbreeding between early proto-dogs and wolves throughout a vast geographic range. The detailed history remains unexplored and until further evidence is available, the following section on wolf ancestors must be considered purely speculative.

from Wikipedia

Dog drawing by: Hitler

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