Ancient foragers suffered less from infectious diseases. Most of the infectious diseases that have plagued agricultural and industrial societies originated in domesticated animals and were transferred to humans. ~ Israeli historian Yuval Noah Harari
Animal domestication was often a form of food storage. Those animals indifferent to human presence and induced into appreciating edible scraps were the first to become livestock. Pigs and poultry overcame their hesitations early on.
8,500 years ago, itinerant farmers from the Near East encountered hunter-gathers as they came into Europe. The immigrants brought pigs with them which they had domesticated in their native lands nearly 1,500 years earlier. Europeans so got the taste for pork that they domesticated the wild boar that roamed the continent even before they took to tilling the soil.
Most animals domesticated for food, such as pigs and chickens, are behaviorally and cognitively quite similar to their ancestors and wild counterparts, as they are mainly selected on physical characteristics. This stands in contrast to the case of dogs and wolves, who, of course, share a number of characteristics with each other but, because dogs were selected as companions, are also distinctly different on several cognitive and behavioral dimensions. ~ American zoologist Lori Marino
Dogs and horses can offer close companionship to humans only because they are submissively solicitous. This aspect of canine behavior is well-known but is also true of horses. When a horse needs help it solicits a human using visual and tactile signals. How a horse tries to communicate depends on what the horse thinks the human knows.