Ever wonder how dogs became domesticated?
It was long believed that prehistoric humans, some time between 15-50,000 years ago, entered wolf dens and purposely selected wolf cubs to bring home and tame. The idea is that over time, wolves became tamer and tamer, until eventually they ended up as the domestic dog.
That theory is now considered probably untrue. It is more likely that when humans began forming permanent settlements (closer to 15,000 years ago) wolves were attracted to these settlements as sources of food remains and other edible garbage. Some wolves would have fared better at this than others. Wolves who were so fearful that they would not come at all near the camps would not have benefited. And wolves who were so aggressive that they attacked or threatened humans would have been disposed of by hunters. But some wolves, the most "social" wolves, would have thrived. These wolves' cubs would have had genes that promoted sociability, and then they would do even better. Studies of captive fox populations in Russia suggest that as genetic behavior towards humans changes, morphology (what the animal looks like) also changes, so as the wolves got tamer and tamer over the generations, they would have changed appearances and so become our domestic dog.
I think that this theory sounds extremely likely (and it even goes a long way to explain why dogs are wired to eat whatever's in sight even if they're not hungry at the moment -- that's true of all scavengers.) But how could we ever test it?
Look to Florida. The endangered Key Deer, a native species, has been threatened by humans encroaching into their habitat. But the Key Deer (at least some of them) seem to be making behavioral modifications in order to survive this encroachment, though it seems to be changing them somewhat in the process.
There are now two distinct sets of Key Deer population. The first are still truly wild, timid, retreating from humans. But the second population is becoming less afraid of humans, almost to the point of sociability. These less-fearful deer can benefit from human landscaping and sometimes even direct human interaction. This population of deer is beginning to look different from the truly wild population -- they are much bigger. And they are having more babies.
Dr. Hare at Duke University's Canine Cognition Center suggests that these deer may be in the process of domestication much like early domestic dogs. Further, he suggests that humanity as we know it might be in a "domestication event" the likes of which has never been seen before since the beginning of time itself. Many species are learning to live within human environments and even gaining a benefit from it -- think of coyotes and seagulls living in dumps, and city pigeons where the tamest ones/the ones that will get closest to and interact with humans seem to get the most food.
If we are truly in a domestication event, there is a lot to think about in terms of long-term animal welfare as well as environmental factors.