Ethology and animal behavior

In this video, we will begin to explore the field of ethology, which is the study of animal behavior. Animal behavior and the word itself, ethology, it has its roots in the Greek ethos. You also might be familiar with the word ethics. Ethos and ethics, you keep seeing this 'f' and it's generally referring to something's character. So, you could see this is the study of the character of animals or, in general, the behavior of animals.

So let's just first think of a framework, and then we're going to try to apply it to different types of animal behaviors that we see. So, first, what is behavior? Well, you have some type of environmental stimulus, and it evokes some type of a response in the animal. And so that is a pretty good definition of what behavior actually is. It's some type of response to stimulus in an environment. The stimulus could be another animal doing something; it could be the temperature; it could be the availability of food; it might be the sun setting—who knows? But it's some type of response due to that stimulus.

Now, so that's the first thing we're going to look at. The second thing is: well, how did this behavior come about? Was it learned? Was it innate? So a learned behavior is when an animal saw something else do and said, "Hey, that's a good idea!" Next time I see that stimulus, or they might not even be thinking that much about it, but somehow they are trained to do it whenever they did that behavior, they got rewarded somehow or whatever else. The other option is it's innate; the animal would have done it even if there was no training, even if they never observed it. It's in their genetics somehow.

And the third question we're going to ask ourselves is: well, what's the benefit here? What's the benefit here, especially in a case or in a context of natural selection? Or, you know, how did it evolve? It should have evolved because there's some benefit where the members of a species that have that behavior are selected for in natural selection.

So now that we have a little bit of our framework, let's think about some animal behaviors. Well, right over here, I have a baby crying. And yes, we humans—it’s nice to remind ourselves that we are animals. We should feel very proud to be part of this animal kingdom. And the behavior here is the child crying.

I'll assume that this child is maybe hungry. There are many reasons why a baby might cry, as you might discover when you have one. I have three now, and I think I have most of the reasons down. But let's say for in this context, the stimulus is a lack of food, which leads to the response of crying. My two-year-old just the other day was screaming from his crib, "I want food!" And he was kind of crying it out.

So, that type of behavior where you have lack of food leading to crying? Well, let's think about, let's actually first think about what's the benefit of that. It's almost obvious, or it's almost too obvious. Well, if a baby didn't cry, then the parents might not notice that it's hungry, and the baby might not get the food, might get malnourished, or in an extreme case, might starve.

And so by crying, it allows other people to say, "Oh, I need to feed that baby!" Because a baby isn’t able to go hunt down its own food; it isn’t able to, you know, get in the car and go buy a sandwich, or go to the fridge and make itself some cereal. It needs other people to do it. Even the behavior that I might have as a parent to say, "Oh my god, my son is crying; I need to go get him some food," that itself is a behavior.

So there's one stimulus: the child is hungry leading to the response of the child crying, and then that response is then a stimulus to me to have the response of, "Oh, let me feed my child so that they stop crying." You can imagine it has a significant benefit in natural selection. You could imagine, and I think it would be—you wouldn’t—this probably happened in our evolutionary history far before humans came about.

But whatever organism you're talking about or some animal, if the offspring that are better at making it known that they are hungry, especially if these offspring are dependent on their parents or something else to get them food, well, the ones that cry are more likely to get the food and are more likely to survive and pass their DNA on to future generations. And so it makes sense. This is almost an obvious one, why this is favorable from a natural selection point of view.

Another interesting question, and this is—you should even ask this about your own behavior. Anything that you observe is that behavior learned versus innate? I haven't run any experiments here, but I would guess my hypothesis is that the baby crying in response to not having food, that this is innate. No one has to teach a baby to do this; it's somehow programmed into their DNA. It's programmed into their brain; they don't have to be trained to cry.

Now, when my five-year-old cries because I didn't give her dessert, even though she has just eaten a full meal, I think that might be learned. She might be seeing that, "Hey, her younger brother tends to get his way when he cries. Maybe at five years old, I should still do that," even though I really don’t have to because I really don’t need that dessert. That might be learned.

So once again, it depends on the context, and it's a really interesting thing to think about. But let's move on to other members of the animal world. This right here is Pippi, who works at Khan Academy. So Pippi, and when there is food around, Pippi acts extra cute and needy.

So let’s—the stimulus here is food. I guess there’s a food theme here; maybe I need to be eating some food. So maybe when I have a lack of food, my response is making a video about it. But anyway, when Pippi is around food, she acts extra, extra cute and needy, and I think all of us have seen dogs behave this way.

It might just seem like a simple thing, but this could actually be a very important behavior for a dog. We know what the stimulus is, what the response is—learned versus innate. Well, it might be a little bit of both, and that's something you'll see as you try to analyze more and more animal behaviors—is that, well, it's sometimes a continuum. Maybe there's an inclination to do that behavior, but by learning it, they get better at it.

So maybe Pippi would have always been somewhat needy around food, but when these other dogs do it, they are more likely to learn that behavior. And a good example of something that's in between learned and innate for human beings is language. We could do a whole series—people dedicate their lives to studying human language. But we think we have a lot of reason to believe that humans have an innate bias to wanting to communicate and having structured language.

But you clearly learn your particular language. If human beings were to just throw a bunch of babies on an island, which sounds like a very— it is a very cruel experiment—at some point, if they survive, they would develop their own language. But we also know that if you put a baby in the context of someone speaking English, or French, or Hindi, or whatever else, that they will actually learn the language.

So these two things are not always one way or the other; in fact, in most cases, it's someplace in between or it's a combination of learned and innate. But let’s go back to Pippi. Why is that a—what's the benefit there? What's a way of getting food? Why would that be selected for?

Well, the wolves thousands of years ago that were better at kind of getting close to humans and acting extra cute and needy—well, they were able to get food; they didn't have to hunt it down themselves. And that's actually how dogs came about, and we could think of many, many other examples.

So this right over here, this is a possum playing dead, kind of a famous behavior. So when there is a threat—when there's a threat, maybe a predator around—this possum plays dead. I would guess it's interesting to think about whether it's innate or learned. This is innate; they didn't have to see another possum do this behavior. In fact, they might not even be able to help it; when their stress hormones go up high enough, they might just turn into this looking dead state.

And a lot of times, just to—you know, when people say that's instinct, they’re often talking about an innate behavior. Instinct is not saying, "Oh, well, maybe if I play dead and act really well, that predator might not come." It just can't help it; maybe its hormones go up, and it just gets into this state. And you might say, "Well, what's the benefit there?" It seems like it's easy to catch. Well, other animals might not like eating things that are dead—maybe things that have a disease or whatever else, and it doesn't want to catch it.

And so something about the evolutionary past of possums, or pre-possums, they were selected for; the ones that were able to do this had a higher chance of not being killed and then passing on their offspring. And so we now see this in possums. Once again, we could go through a whole range of behaviors, from hibernation.

There's also a phenomenon, actually, that there are things like hibernation where bears famously hibernate for the winter. Why is that useful? Well, the stimulus is it's getting colder in the different part of the season, and so they'll hibernate. Why is it useful? Well, they lower their metabolic rate, their need for food when there's less availability of food. And so that also can give you clues about why it might have been selected for.

There's actually a similar form of hibernation, I guess you could say, called estivation. Estivation, which I actually didn't know this word until I started looking into this; and this is a—sometimes in the U.S., they don't put the 'a' in front; it's just estivation with the 'e'—but this is a form of going into a lower metabolic state when things are really hot or very dry when you don't have the availability of water.

So it's less familiar than hibernating for the winter, but it's another form of getting into a lower metabolic state. You might say, "Well, why does that happen? Why would that be selected for? Which animals do that? And is it innate? Is it learned?" I would propose that both of these are innate, that most of the animals that do this would do it regardless of whether they somehow got trained or observed some other animal doing it.