Humans celebrate diversity in dogs that we abhor in humans. by
DaPugletAs Darwin pointed out in the The Origin of Species
(1859), species often exhibit enormous variation. Darwin was a
pigeon breeder and described at length the astounding variation
that, with the help of artificial selection, pigeon breeders had
succeeded in cultivating in an otherwise humdrum bird species.
Similar forces operate on Canis familiaris and, if anything,
have produced an even more remarkable range of variation. Simply
on the dimension of weight, dogs exhibit a scale of variation
that beggars belief: the smallest dog on record is the ultra-
petite Tiny Dancer, a toy Chihuahua that as a full-grown adult
weighed in at a mere eighteen ounces. At the other end of the
scale, the heaviest dog on record, Zorba, is an Englishl mastiff
that tipped the scales at 343 pounds. Thus, these two very
different members of Canis familiaris have adult body weights
that are separated by a factor of more than three hundred. By
contrast, physiological d