I really wanted to see in a different game that sort of asked the same question in a slightly different way what the foxes would do. So we came up with a new way to look at a larger population of foxes so that we didn't have to do any kind of exposure for the control line. And then we could really test them with the very same experience, and also, I didn't wanna use food. Because it just ended up, the population of foxes, they are very sensitive and their appetite fluctuates a lot. So if I could find a game where there was no food involved, that meant I could actually test them, not for some kind of food reward as we do in all the other games, but I could actually look at just a social reward. And what would their preference be and would they use human gestures even when it wasn't for food. So the game was very simple. You can see that the person in this diagram is touching one of the two little toys there. And there was like a little piece of metal that could touch on each toy and it would makes sound kind of a boing boing sound as touched it. And then it would of course potentially attract the attention of a fox who's watching. And when that toy, in the beginning when you touch it, it was out of reach but then you just would push it within reach of the fox and then they had the choice of, did they want to touch the toy that you touched? Or they could touch an identical toy on the other end of the table that you had not touched. We knew from previous experience that they love to play with these toys. And so it gave us a really good opportunity to see which toy would they play with and what was their first choice when you touched one of the two toys. Now we did a control, we also looked at what happens if you don't touch the toy, what happens if a feather touches one of the toys. So this is a non-social or at least it's a non-human cue. And the question was, would the foxes still be interested in touching the same toy that a feather touched or not? And the results were really interesting because it really mattered which population we looked at. So here is a picture of touching one of the two toys and you can see the fox watching and then there's the feather touching one of the two toys and this is what it would have looked like when we played the games. And here are two populations of foxes. The top being the experimental line and the bottom being the control line. And what we found was that when the experimental population was shown a person touching one of the two toys, they had a very strong preference to touch the same toy that you touch. Whereas if they saw a feather touch the toy, they didn't really choose that toy. They would just choose at chance. And we found the exact opposite in the control line. The control I had no interest in touching a toy that you touched. They were much more interested in touching a toy that the feather touched. So even though these populations are raised on the exact same food in the exact same way, they live together essentially. They have this very different response to human gestures versus a feather. And it can only be explained by the selection for interests and against aggression in the experimental line. So at this point, I was really convinced that we were looking at something that was a real difference between these two populations. And I felt like we had a really good handle on what may have driven, not just the change that we see here in the domesticated foxes that we know what the selection pressure is, but also, in our best friend's dogs. So, the foxes have really taught us that you can have selection against aggression. Lead to changes in morphology, physiology, behavior, but also in potentially psychology and the preferences that animals show towards human gestures versus nonhuman things. And I think it really helps potentially support the domestication hypothesis the idea that dogs actually experience something very similar. As early wolves started to evolve into dogs I don't think it was the humans went as we talked about earlier in lecture two. I don't think humans went and said oh isn't a great idea to bring some wolves in and have them together with our kids as we go hunt and gather. I think it was more likely that dogs actually, or I should say early wolves, chose us, that wolves started living close to us. That they started relying on people, and that the only wolves that could do that were the wolves that weren't aggressive, that weren't fearful, were actually interested in people. And what you see with the Galiah fox experiment is when you start selecting a canid, to be friendly and interested in people, you end up with a fox like this, that has pie ball coat. A very high frequency in a population of curly tails, and all sorts of other changes including being very good at reading human gestures. So, I think the foxes really for me solved the mystery of why dogs are remarkable at using human gestures. It was, they were selected to be interested in people, and they were selected to wanna interact with people. And that allows them to use the old cognitive skills that we see in wolves. And using gestures, or I shouldn't say gestures, but using social cues with each other, but they can use it in a new context, they can use it now with people. They're not afraid of people, they're not aggressive towards people, they want to actually use the same skills they use with each other with their same species social partners. They wanna use it with people. But it ends up that people are obviously using gestures. And they're intentionally communicating and trying to help in a way that an individual of your same species wouldn't. And because you're interested, and then because you're interacting with people, you as a species start to use a new type of communicative behavior. And potentially develop an understand of communicative intention. In summary, the Russian geneticist lead by Dmitry Belyaev and Lyudmila Trut and Irina Plyusnina selected a population of foxes to be interesting and friendly to humans. This experimental line was compared to a control line that was not selected based on their behavior towards humans. The experimental line shows the expected behavioral change. They're interested in people, not fearful, but they also showed a high degree of accidental changes including the morphology and changes beyond that that are typically seen in domesticated animals. Things like floppy ears, curly tails. The experimental populations based on my own work, working with my colleagues in Russia. They also, interesting enough, use human gestures more than the control line, even though they were never selected based on this trait. So what then got us excited was, remember I promised you we were gonna bring this back to humans, what does this mean for us? Is it that if you select against aggression and for interest, not just in dogs, wolves, and foxes, what about in primates or even humans? What would it mean for us? So that's what we'll address next.
