Differences in the Behavior of Landraces and Breeds of Dogs - Genetics and the Behavior of Domestic Animals - page 217

entirely explained by these timing differences, suggesting the importance of
early environment in the production of these breed-typical behaviors.
Fox's (1978) experiments have provided an alternate hypothesis. Hybrids
between dogs and coyotes performed some predatory motor patterns but
could not organize them in functional sequences. Coppinger et al. (1985)
argue that mongrelization of dogs is a method of disrupting functional
sequences in a way that mimics neotenization. Since we have good records
of hybridization between breeds in the creation of new breeds, this hypothe-
sis is very plausible. For these reasons many true breeds have evolved where
animals get sexually isolated into small populations. And genealogy becomes
a frequent topic of breeding discussions.
Household Dogs
Ecology
Household dogs are a very large population in western countries but a small
proportion of the total world population. In the U.S. and Europe there are
about 150 million household dogs ( AVMA, 2007; European Pet Food
Industry Federation, 2010 ). In the U.S., about 72 million dogs live in 37% of
the households ( AVMA, 2007 ).
The literature on the function of pets and companions deals with physical
and mental health benefits for humans. The health and well-being of the
assistance and therapy dogs, also, is highlighted in the literature (e.g., Wells,
2007, 2009 ). However, current findings of this research are mixed ( Esposito
et al., 2011; Herzog, 2011 ).
The literature generates the impression that “feeling better” is a biological
benefit. Yet, a “sense of calm” in the presence of a dog does not demonstrate
increased reproductive or economic capacities, which are the true test of
mutualism. Any true biological benefits would also have to be measured
against the cost of the dogs in terms of food, health, environment, and wider
issues about their presence in human society ( Serpell et al., 2000 ).
Authors concluding that dog is “man's best friend” do not usually men-
tion the estimated 4,500,000 dog bites/year in the U.S. ( Sacks et al., 1996 ),
an average of 323,085 per year of which lead to emergency room visits
( Quirk, 2012 ). Nor do they include the 85,000 emergency room visits in the
U.S. as a result of falls caused by pet dogs ( Herzog, 2011 ), or the enormous
nuisance problems of barking dogs and dog feces.
Phenotype
This group is phenotypically the most variable, from very, very large to
very, very tiny. The claim is that the domestic dog is the most variable spe-
cies in Mammalia. However, the mutations for gargantuanism or dwarfism