Genetics of Domesticated Behavior in Dogs and Foxes - Genetics and the Behavior of Domestic Animals - page 371

Results of the selection against defensive aggression became apparent after a
few generations of selective breeding. Subsequently, selection for an emotionally
positive (“friendly”) response to humans was applied. Behavior of all foxes was
evaluated in a test with five consecutive stages: (1) observer approaches the cage;
(2) observer stands near the closed cage; (3) observer opens the cage door and
stands near by; (4) observer attempts to touch the fox; (5) observer closes the
cage door, then stays near the closed cage ( Trut, 1980a; Trut et al.,2004 ).
Fox behavior in this test was scored based on their response to humans using a
categorical system ( Table 10.1A ). Behavior of young animals was tested several
times during development and the final test was giving to all pups at 7

8month
of age. Only the tamest individuals in each generation, less than 10%, were bred.
At the same time a deliberate effort was made to avoid inbreeding ( Kukekova
et al., 2004; Trut, 1999, 2001; Trut et al.,2004 ). The response to selection was
extremely rapid ( Table 10.2 ). Improvement of behavioral scores recorded in fox
pedigrees clearly showed genetic inheritance of tame behavior. It is important
to note that except for the first few generations of selection, foxes from the popu-
lation selected for tame behavior did not receive special handling. All human
contacts were, and continue to be limited to maintenance and testing procedures.
Foxes from the tame population show a friendly response to humans as early as
one month postanatal and remain friendly throughout their entire lives. Tame
foxes are eager to establish human contact, whimper to attract attention, and sniff
and lick similar to dogs ( Figure 10.1A ). The behavior of tame foxes can be
observed on the webpage: http://cbsu.tc.cornell.edu/ccgr/behaviour/Index.htm .

TABLE 10.1A

System for Scoring Behavior in Tame Fox Population and
Selecting the Most Tame Foxes for the Breeding Program

Animal Reaction Scores

Passive-protection response; fox avoids experimenter or bites if stroked or
handled, comes if offered food.

0.5 1.0

Foxes let themselves be petted and handled, but show no emotionally
friendly response to experimenter.

1.5 2.0

Foxes show emotionally positive, friendly, response to experimenter,
wagging tails and whining.

2.5 3.0

Foxes are eager to establish human contact, whimpering to attract attention
and sniffing and licking experimenters like dogs. They start displaying this
kind of behavior before one month postnatal age.

3.5 4.0

Tame behavior is scored from zero (representing “neutral” behavior; an absence of both active
aggressive and tame responses directed towards the observer) to 4 (representing the most tame
behavior).
Source: Trut (1980a) .