From an evolutionary point of view chickens are the most successful animals in the history of the plant. A few millennia ago it found another species of animal that would meticulously tend to its needs. This host species was recruited to feed and to tend for it, help it breed prolifically. That caused an explosion of the number of individuals living on the planet. Today there are about 25 billion chickens inhabiting all corners of the world, while the hosts, human beings, number just seven billion. https://frederic-38110.medium.com/how-evolution-works-83f7f9f98760