Whether you love them, hate them, or just think some of them are delicious, domesticated animals are an intrinsic part of our lives. From the Dachshund to the Holstein to the thoroughbred, humans have transformed wild animals into docile, useful companions and livestock (and sometimes genetic abominations). But how did this happen? How did we convince these beasts not to kill us and, for some, to be our friends? (That weird friend who licks your face and poops everywhere.) Well, it depends on the species.

Dogs

Dogs were the first species humans domesticated, in no small part because they started the process themselves. Wolves would follow nomadic  tribes, as humans were a dependable source of scraps cast aside with abandon (we have, apparently, always been THE WORST). These were likely the less-dominant members of their packs, with more social than aggressive tendencies. Humans, meanwhile, learned the advantage of having the dogs nearby as early warning systems against other predators, so they began enticing them closer and selecting for amicable dogs. Wolves have several characteristics that helped them along their path to being good dogs. Yes, they are! They ARE good dogs!  They are naturally cooperative, can exist without an all-meat diet, and can find food on their own.  The scientific community still debates about when—and even how many times—this event occurred, but we know that before we even developed agriculture, we had our mutts at our side. If any of this disagrees with that movie, Alpha, I’d trust them. They make more money than I do.

This process was re-created by a Soviet scientist in the 1950s with foxes; over several decades, he developed foxes that appeared friendly based on behavior,  such as wagging their tails when seeing humans. Over time, they developed shorter muzzles, floppier ears, and fewer teeth—traits all found in modern dogs, but at much lower rates or not at all in wild canids. He did not select for these traits; his only criteria for choosing which foxes to breed was behavior. Further research indicates that the behavioral change came from changes in the hormonal system related to adrenaline, which is itself related to the development of physical characteristics. They are, in a sense, developmentally stunted; permanently wide-eyed, lovable puppies.

Cats

Cats, it turns out, have always been cats. After watching the dogs scrounging for scraps for tens of thousands of years, they decided following our nomadic tribes was way too much effort. They waited for us to develop agriculture, settle down, and attract some delicious, delicious rodents.  This seemed to work out pretty well for us, and we kept the wild cats close by and hunting to protect our precious grain. This led to very little genetic distinction between modern house cats and wild cats. Essentially, cats weren’t domesticated at all—we just invited psychotic hunters into our homes, and they agreed because we are warm and have food.

Food Animals

Herd-bound herbivores, such as sheep, goats, and ancestors of cattle, had been prey for humans long before domestication. Hunter-gatherers appeared to have figured out how to maximize their prey availability for the long term. They didn’t directly breed the animals for their mild manners, but through selective hunting of the most aggressive young males and by leaving more breeding females, they were able to create populations of more docile, complacent animals. Eventually they became so complacent that we got to (had to?) guard over them, creating a positive feedback loop of dependency—they don’t get eaten by other predators, we get a reliable protein source. It’s a livin’!

Transport Animals

These critters came latest to the domestication game. Long after the domestication of carnivores and prey, humans figured out how to target other animals that looked useful. They captured and bred species such as horses, camels, and donkeys; first for their milk and meat. But they unlocked these animals’ real potential when they realized they could sit on them. If you’ve never been on a horse, it beats the hell out of walking. They captured wild animals with the intent of breeding them for milk production, durability, and speed, and boy, did it work. Still, this is not possible with every species: despite attempts, gazelle and zebra lack the inherent behaviors necessary for domestication. Sorry, Africa.

Humans

Plot twist! That’s right, nerds. According to some hypotheses, we’re domesticated too! Remember those dogs and foxes? In the last tens of thousands of years, we’ve developed similar physical changes, such as smaller teeth and narrower bones. When we settled in one spot and became community-focused rather than individual-focused, aggression and strength was not as advantageous as cooperation. One large, aggressive human could not take on a group of humans working together to defend their property. There are many reasons for humanity’s overwhelming success on Earth, but our ability to work together without killing each other (at least, most of the time) has been a massive advantage.

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