- 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,
and you also might be familiar with the word, ethics.
Ethos, and ethics, you keep seeing this "eth",
and it's generally referring to something's character.
So you could say this is the study
of the character of animals, or in general,
the behavior of animals.
And so, let's just first think of a framework,
and then we're gonna 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,
some type of a response in the animal.
And so that is a pretty good definition
of what behavior, 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 gonna look at,
the second thing is, well, how did this behavior come about?
Was it learned?
Was it innate?
So a learned behavior, that animal saw
something else doing it, 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.
And the other option is that it's innate,
the animal would have done it even if there was no training,
even if they never had 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, and it should have evolved
because there's some benefit, where the members
of a species that have that behavior, are selected for.
So 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,
and I'll assume this child is maybe hungry.
There's 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 in this context,
the stimulus is a lack of food.
Lack of food, and it 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,
and so that type of behavior,
where you have lack of food leading to crying,
well let's think about it, 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 do that,
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,
say, oh, I need to feed that baby.
Because a baby isn't able to go hunt down it's own food,
it isn't able to, you know, get in the car
and go buy a sandwich, or go the fridge
and make itself some cereal, it needs other people to do it.
And 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, the stimulus.
So there's one stimulus, the child's hungry,
leading to the response of the child crying,
and then that response is then
a stimulus to me, to say, to have the response of,
oh, let me feed my child so that they stop crying.
And so 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,
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, that a baby,
no one has to teach 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 lets move on to other members of the animal world,
this right here is Pippy, who works at Khan Academy,
so Pippy, and when there is food around,
Pippy acts extra cute, and needy.
So let's, so 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 (laughs) when Pippy is around food,
acts extra, extra cute,
and needy.
And I think all of us have seen
dogs behave this way, and it might just seem
like a simple thing, but this is actually,
could be a very important behavior for a dog.
That, you know, we know what the stimulus,
and 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 Pippy would have always
been somewhat needy around food,
but when it sees other dogs do it,
then more likely to learn that behavior.
And a good example of something that's
between learned and innate for human beings is language.
Now 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 this structured language,
but you clearly learn your particular language.
If human beings were to just,
if you threw a bunch of babies on an island,
which sounds like a very-- it is a very cruel experiment,
at some point, they, if they survived,
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 some place in between,
or it's a combination of learned, and innate.
But let's go back to Pippy, 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 can think of many, many other examples,
so this right over here, this is an opossum playing dead,
kind of a famous behavior.
So when there is a threat, when there is a threat,
maybe a predator around, this opossum plays dead.
Plays dead.
I would guess, it's interesting to think about,
whether it's innate, or learned, that this is innate.
That they didn't have to see another opossum
do this behavior, in fact, it might,
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.
It's not saying, oh, well, maybe if I played dead
and act really well, that predator might not come,
it just can't help it, maybe you know,
it's 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 it has a disease, or whatever else,
and it doesn't wanna catch it, and so,
something about the evolutionary past of opossums,
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 opossums.
And once again, we could go through
a whole range of behaviors, from hibernation,
there's also a phenomenon actually that,
so there's things like hibernation,
where bears famously hibernate for the winter.
Why is that useful?
Well the stimulus is it's getting cold,
or in a different part of the season,
and so they all hibernate.
Why is that useful?
Well, it's, 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, or form of hibernation,
I guess you could say, called aestivation,
aestivation, which I actually didn't know this word
until I started looking into this,
and this is a, and sometimes in the US
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 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.
And 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 the animal, most of the animals that do this
would do it regardless of whether they somehow got trained,
or observed some other animal doing it.