What happens when birds are domesticated? Study shows that domestication makes chickens larger. When selected over multiple generations for reduced fear towards humans, red junglefowls (ancestors of domestic chickens) grew faster and larger, laid larger eggs, and had more efficient metabolism than the fearful counterparts. The tamed birds had higher serotonin molecules, which are involved in fear and metabolism. Researchers concluded that domestication likely correlates to favorable traits via serotonin increase. They are now looking at genetic basis of these changes in bold, tamed fowls.
Research paper:
Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)
Biology Letters (2015)
News coverage:
http://news.sciencemag.org/evolution/2015/09/here-s-what-happens-when-you-rewind-clock-chicken-domestication
Something About Science 
McConaughey Fried Chicken~!
Yup! I had Intersteller in mind when I draw the comics 🙂