Meet the pumpkin toadlet.

They’re a genus of adorable, super tiny Brazilian  frogs…that are bad at jumping. Look at that.

They’re,  they’re just doing their best! But why are they like this? How would a  scientist even begin to figure that out?

Q&A sessions with frogs tend to be…one-sided.  I know — I’ve had my fair share. The quest to understand animal behavior brings  together researchers from the furthest corners of   biology, combining knowledge about evolution,  body structures, cells, hormones, and more. Their powers combined can lead to some  amazing insights not only about why   animals do what they do but also whether  we were born knowing how to do that thing.

Or whether we learned it along the way. Or whether it’s…somewhere in between. Hi!

I’m Dr. Sammy, your friendly neighborhood  entomologist, and this is Crash Course Biology. Let our powers combine!

Earth,  Fire, Wind, Water…THEME MUSIC! [THEME MUSIC] An animal’s behavior is what it does,  its actions. Which covers a lot! Whether it’s a panda rolling in horse poop to  stay warm (eww) or your goldfish hanging out on   the side of the tank the food comes in, animals  get up to some brilliant and bizarre stuff!

And for a scientist, understanding  the hows and whys can be a journey. Like, if you asked me, “Hey, Dr. Sammy, how  does monarch butterfly migration work?”...

I’d ask you to break it  down into smaller questions. Like, do you want to know what systems help them   navigate? Or what triggers them to start  flying?

Or why this behavior evolved? Every question in animal behavior has  dozens of smaller questions stuffed inside. And when pursuing answers to those  questions, a researcher is typically   operating on one of two levels: the  proximate level, or the ultimate level.

So, in the case of our pumpkin toadlet, we might ask ‘what’s happening within or  around it, to make it hop like that?’. Those are questions on the proximate level,  which typically focuses on how behaviors happen. As in: how is this behavior triggered?

And how  does this action develop over an animal’s life? Well, if we look around the toadlet,   we might find that it’s jumping wildly  away when there’s a threat nearby. But that’s true of lots of frogs.

So,  next, we might look within the toadlet. And there it is: there’s a structure inside their   ears filled with fluid that should slosh  around to help the animal orient itself. Except, the pumpkin toadlet is so small,   the laws of physics prevent that  fluid from moving fast enough.

So, when they launch, they have no idea how  their body is oriented. Which, to be fair,   is also how I, an adult man, feel on a trampoline. Anyway, upon further investigation,   we’d learn that this behavior doesn’t  really change over toadlets’ lives.

In the case of our toadlet friend, it can’t be  taught or untaught, it’s just the way they are. But why?? That nagging question brings us to  the ultimate level — which despite the name,   isn’t better than any other type of  research and doesn’t involve a frisbee.

Instead, at this level,   we’re looking at why behaviors evolved  and stuck around in the first place. The ultimate reason why they exist. Why does jumping horribly help pumpkin  toadlets survive or reproduce?

In this   case, it’s not that their acrobatics  give them an edge — but that being   so small seems to be helpful for  survival in their environment. And the poor jumping, as we know, is  a result of their size. So basically,   they get more benefit from being  small than they lose by being chaotic.

At the ultimate level, we might also consider  the evolutionary history of this behavior. So, we’d look through this frog’s  family tree to figure out when the   switch flipped from “wumbo” to “mini”, and  how their bodies changed along the way. And all of these questions about animal  behavior tend to range widely throughout   different areas of research done  by different types of biologists.

Even within the proximate and ultimate levels,   there’s a super wide variety  of specialization needed. Think about it. Understanding evolution  is going to require different knowledge   and research than figuring out  the anatomy of a frog’s ear.

By investigating all these specific details,  every team can contribute one piece of the puzzle,   until suddenly, we have a clear picture  of how and why animals do what they do. And part of that picture is where, or  how, or whether they learned the behavior. How much is it a conscious decision  versus some automatic script?

Does my goldfish have free will? Well,  I can’t really answer that last one. But I can say: when it comes to animal  decision-making, there’s a sliding scale,   with programmed or innate behaviors on one  end, and learned behaviors on the other.

Starting at one end of the spectrum,   we have innate behaviors, which  animals don’t have to learn. These things are built into our  DNA. Like toadlets flailing,   or little baby humans grasping at fingers.

And although the behaviors themselves might look  involved, they don’t usually require much thought. One example is a reflex. If your great-aunt’s  obsession with incense bothers your nose,   you’re going to automatically sneeze.

You never had to learn how, and you  don’t think about it. It just happens,   like how some apps come  pre-installed on new phones. And then there are fixed action patterns,   which are like more involved reflexes  found in some non-human animals.

They’re a set of movements that can happen all   across an animal’s body in  response to some stimulus, or cue. For example, if a praying mantis  sees a tiny insect scurry past them,   under the right conditions, they’ll  automatically strike at it — and they   can’t stop or change directions once they get  going, even if the prey has already escaped. There are countless examples of things  animals just do because they’re innate.

These can also include broader patterns,  like the circadian rhythms that influence   when animals sleep and wake up. And circannual  clocks, which influence seasonal migration. These innate rhythms are why you probably  feel sleepy around the same time each day,   and why you may hear outrageously loud  migrating geese at particular times of the year.

Most of these innate behaviors  stick around in populations or   species because they give individuals  a survival or reproductive advantage,   and so the behaviors continue  in successive generations. And that means innate behaviors  can be shaped by evolution, too. If one built-in foraging strategy  or parenting behavior makes an   animal more likely to survive or make babies,   that behavior will be selected for — just like  physical traits, such as fur pattern, would be.

But as someone who’s spent your  whole life in the animal kingdom,   you’ve probably noticed there are plenty  of complex behaviors that aren’t completely   built-in — things we and other animals  have to be taught and decide to do. Like communication. Let’s  go to the Thought Bubble… Honeybees love to dance.

But they don’t use  their smooth moves to rack up millions of views,   not intentionally anyway.  They dance to communicate. Bees that search for food, called  foragers, perform what entomologists   call a “waggle dance” to tell other  bees about the food that they’ve found. Based on how long they waggle  their abdomens and at what angle,   the bees can convey the food’s  direction, distance, and quality.

But some scientists in China wanted  to figure out if these moves were   taught to the foragers by older bees,  or if they knew how to dance innately. So the researchers took some young  bees with no dance experience and   separated them from their colonies. And  they compared this group to some regular   colonies with veteran foragers that  could show the young bees the ropes.

At first, the bees without role  models were… very bad at dancing. They couldn’t accurately  indicate where the food was,   while the bees that watched the more  experienced dancers were pretty spot-on. After a while, the first set of bees did get  better at saying which direction the food was in,   but they never could get the waggle  length down to indicate distance.

So their dance moves could  be improved on their own,   but they’d get better faster — and nail those  distance signals — with a good dance teacher. Thanks, Thought Bubble! While  some communication can be innate;   many mating dances come pre-installed.

Often, communication skills  — whether they’re visual,   chemical, or based on touch or sound —  are something a baby animal has to learn. To a biologist, learning is the process that  makes links between experiences and behavior. For instance, when a baby goose  bonds with the first animal it sees,   that’s a type of learning called imprinting.

The goose has no idea it’s a goose, so it assumes   the first living thing it sees must be  the same species. Good insight, goose! There’s also spatial learning, like when that  goose gets older and learns where their nest is.

The most complex kinds of learning  are cognition and problem-solving. Cognition involves analyzing information from  the environment, including making decisions. And problem-solving is… well, problem-solving.  You participate in these things all the time.

Navigating to a new classroom, figuring out what   to put on your sandwich when  you’re out of peanut butter,   deciding if jeans are juuuust smelly enough that  you have to wash ‘em — they’re all included. And these aren’t just human skills. Other primates, dolphins, octopuses, and more are  capable of these kinds of learning.

Like, in a 2016 study, octopuses were  taught to push L-shaped blocks through   a square hole. Basically playing one of those  shape-sorter games human toddlers are into. This kind of learning is way on the other  side of the spectrum from innate behaviors.

These skills do indirectly depend  on an animal’s genetics, but mostly,   they have to be taught and are conscious actions. So, learned behaviors are strongly shaped by an  animal’s experience, environment, and culture. So, you’ve got innate behaviors on one end of  the scale, and learned behaviors on the other.

But there are plenty of behaviors  that are somewhere in-between,   too, like a honeybee’s waggle dance. Or, for humans, being able to remember  things is one of your innate abilities,   but how good you are at memorizing  can change with practice. It’s a built-in ability plus  some conscious decision-making.

So, how much of an action is up to an individual   animal? It depends on the  species and the behavior. And both proximate and ultimate studies can  help researchers figure out the details.

By combining information from all the different  realms of biology, from body structure to DNA   to evolution, scientists have been able  to sort out key details about how and why   animals behave the way they do, and how much  of that is under their conscious control. This work has answered fascinating questions,  from why pumpkin toadlets can’t stick a landing,   to why pandas roll in poop, and  why birds sing in the springtime. Each of these questions contains  smaller, more detailed ones,   like tiny mosaic tiles.

And by  combining thousands of them,   researchers can put together a beautiful picture  of what makes life on Earth so incredible. Next time…wait a minute…. Next time is EPISODE 50!   Hmmmm, looking at the schedule it doesn’t  seem like there’s a lesson planned.

Looks like I might have to wing it? Guess you’ll   have to tune in to find out how we wrap  this thing up. I’ll see you then!

Peace! This series was produced in  collaboration with HHMI BioInteractive. If you’re an educator, visit  BioInteractive.org/Crashcourse for   classroom resources and professional development  related to the topics covered in this course.

Thanks for watching this episode of Crash  Course Biology which was filmed at our studio   in Indianapolis, Indiana, and was made  with the help of all these nice people. If you want to help keep Crash  Course free for everyone,   forever, you can join our community on Patreon.