Domesticated species are altered from there wild ancestors. Where a low fear of humans have been thought of as an early selection factor for a successful domestication.  Where a low fear of humans have been thought of as an early selection factor for a successful domestication. Selective breeding for a low fear of humans causes changes in other behavioral traits including; Higher hatch weight, more dominate in social situations, larger eggs, better plumage and larger offspring.

Stress is an important factor for domesticated animals from a welfare perspective. Stress- response has been proposed to change during domestication.  Stress is an important factor for domesticated animals from a welfare perspective. Stress- response has been proposed to change during domestication. Earlier studies have shown that  White leghorn (domesticated breed) had a lower initial stress-response but longer recovery and that  Red Junglefowl (ancestral breed) had a higher initial stress-response but shorter recovery.

Selectively breeding for a lows fear of humans have caused changes in Red Junglefowl, with findings that points towards stress-response also changing during domestication. This leads to the question will selecting for fear of humans cause a change in stress-response?