The first domestication of the dog occurred in East Asia, and major ancestor of the dog was a wolf subspecies, Canis lupus chanco. This finding derives from data on the nucleotide sequences of mtDNA and the frequency of genes controlling blood protein polymorphisms in various subspecies of wolves and dog breeds around the world. The results of the allele frequency distribution of genes controlling 16 blood protein polymorphisms, and the incidence of dogs possessing erythrocytes with high potassium (HK) in Japan, East Asia and Europe allowed us to posturate the following hypothesis about the origins of Japanese dogs and the history of their development. In the Jomon period the first dogs entered the Japanese archipelago from southern or northern continental Asia. These dogs eventually spread throughout Japan. Then, during the Yayoi and Kofun periods, other dogs were brought over via the Korean Peninsula, and crossbreeding occurred with the original dogs. The resulted offspring can be assumed to be the ancestors of most of the Japanese breeds that exist today. Ethological studies have revealed a significant breed difference in behavioral traits among canine breeds with Japanese dogs, showing more aggressive dispositions than most of European dogs.

(Communicated by Tamio YAMAKAWA, M.J.A.)