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dif erences to accumulate in the 600 base pairs of dog and wolf DNA that
they compared. But two things were clear. First, among all the Old World
and New World wolves, it is the Asiatic wolves that are the closest relatives
of all domestic dogs and therefore the most likely to be their ancestors. The
anatomists who had fi ngered
C. lupus chanco
as the dog ancestor were right.
The little wolf cub of Oench Village comes from the same group of wolves as
the ancestor of all dogs.
Second, they found that dog populations from eastern Asia seemed to
harbor the most genetic variation. This is the pattern that would be expected
if dogs had originated in East Asia and had later given rise to subpopula-
tions elsewhere. The original population would have brought a good deal
of genetic variation from their wolf ancestors, but because later subpopula-
tions are subsets of the original population they would be expected to carry
smaller amounts of genetic variation.
Both of these fi ndings supported an East Asian origin for at least some
dogs. But was the origin single or multiple? Were dogs domesticated many
times, or only a few times—perhaps only once? And when did domestica-
tion happen? Here the data are more equivocal.
Dif erent dog DNA sequences have been found to fall within dif erent
branches of the Asiatic wolf tree. This could be because dogs were domes-
ticated more than once from dif erent female wolves—the data suggest that
domestications could have happened at least six dif erent times. But these six
events did not give rise to dif erent kinds of dogs—each of the many present-
day dog breeds carries several of these wolf lineages.
The number of mutations that have accumulated in dog mitochondrial
chromosomes allowed Savolainen to estimate that the multiple origins of
dogs took place early, probably at least 15,000 years ago and perhaps twice
as long ago. This is thousands of years before the domestication of other ani-
mals such as the horse. Dogs may have been domesticated independently
in dif erent parts of East Asia around that time, or there may have been a
cluster of domestication events involving several wolves. The production by
artifi cial selection of present-day dog breeds took place much later, which
explains why each breed carries mitochondrial chromosomes from a num-
ber of the ancestral wolf lineages.
