Thanks to Babbel, a language learning  app, for supporting this SciShow video.

As a SciShow viewer, you can use our  link to grow your language skills with Babbel for up to 60% off and  a 20 day money-back guarantee. [♪ INTRO] There’s a great apocryphal quote about the bear-proof trash  cans at Yosemite National Park. When asked about the challenge  of designing a perfect one, a park ranger reportedly said that  “there is considerable overlap in intelligence between the smartest  bear and the dumbest humans”.

We may never know for sure  if this is a direct quote, but it points to a simple  truth that’s a big problem: Humans throw away a lot of trash, and  the bears are good at getting to it. Brown bears can eat anywhere from  30 to 90 pounds of food a day when they’re getting ready for hibernation. Getting that much food is hard, and  as humans have expanded our range deeper and deeper into bear territory,  hunting and foraging areas have shrunk, making it even harder for bears  to find the calories they need.

But that expansion of human  communities has provided bears with a pretty reliable source  of food. Our garbage cans. And while eating our trash gives bears a dinner that humans were throwing out anyway, there are lots of reasons we shouldn’t  be letting bears go to town on our trash.

For starters, having bears wandering through town to snack on trash leads to human-bear conflicts. And when those happen, there are no winners. People get hurt or killed,  property gets destroyed, and the bears tend to either get hit  by vehicles or shot by animal control.

It’s not great for the bears’  original hunting grounds either, because if it’s easy to get food from people, they’re less likely to put  effort into foraging back home, which risks throwing off the  balance of their whole ecosystem. But it’s not just a question of herding  bears back to their original territory. Stopping bears from seeking out trash is a lot more complicated than you might think.

Bears are social learners, and  they figure out how to find food from watching their moms  foraging while they’re young. So if mama bear has learned that  humans are a great source of food, she’ll teach her cubs that. Then her daughters will  teach their cubs, and so on.

And even if a bear isn’t  taught to forage in trash cans, sometimes they just get creative  and figure it out for themselves. Which is why we have generations of  bears that are more than just occasional consumers of our garbage, and have  become reliant on human foods. And it turns out that this  wasn’t even by accident, because people used to leave  trash out for bears on purpose.

From the early 1900s through 1940, trash in California’s Yosemite  National Park went into a dump. But not just any dump. It was surrounded by bleachers and  lights, so park visitors could come watch the feeding frenzy as 20 to 30 bears  fought each other for a shot at food.

Even after the feeding shows stopped,  rangers continued leaving food out in order to attract bears and provide photo opportunities  for tourists until the early 1970s. It’s entirely possible that bears  in Yosemite are still passing down human-food-based foraging behaviors  that their ancestors learned more than 100 years ago. All the more reason that they  want to nosh on our garbage.

Which is why we’ve had to start  making complicated locking mechanisms, or hanging food from a tree, or all other manners of bear-deterrent  methods to keep them out of the trash. But these methods might not stop  bears from trying to get at food. It’ll only slow them down.

That’s because bears, like me, are food motivated. Being food motivated means that one of  the best ways to train them to perform a task or solve a problem is to give them  a reward of food when they’re successful. We know lots of animals, including bears, can perform a variety of actions  to solve puzzles to get food, including pulling pulleys, spinning  tubes, and digging out of holes.

So a lot of our attempts to  keep trash away from bears just end up being a fun challenge for  them, like any food puzzle would be. They just want to solve it and get their food. Which is why our need for bear-resistant  trash cans is constantly growing.

And the biggest hurdle in making a  trash can that’s impossible for bears to open isn’t the bears’ lack of opposable thumbs It has to do with whether the humans  are actually going to use them. Now, despite what our anecdotal park ranger said, the challenge isn’t about humans  figuring out how to use the trash cans. It’s making it simple enough that  they’re willing to use the trash cans.

See, it turns out people are lazy. In one study in Durango, Colorado, a  town that has major problems with bears snacking in trash cans, only 42% of  the trash cans in residential areas and 31% of commercial trash  cans were locked properly. In the same study, only 50%  of fully automatically locking residential trash cans were locked.

Now, to be fair, part of that was  because the locks were faulty or damaged, but even when the city offered  to replace faulty locks, and it doesn’t seem like getting those  replacements in place really happened. And it’s not just a question of what people  are smart enough to do or willing to do, but also what they’re physically capable of doing. Bear-resistant trash cans need to be  strong and secure, but also ADA compliant, so people with limited mobility and dexterity  have to be able to operate them as well.

Some bear-resistant features that  are used include metal reinforcements so trashcans can’t be punctured by teeth  and claws, lids with locks that have to be pushed to open, or posts to secure  cans to so they can’t be tipped over. And with every technology, there’s  always room for improvement. So how do manufacturers prove that their  bear-proof bins are better than the rest?

When a new design for a trashcan, cooler,  or other container comes on the market, it can actually be tested and  certified as Bear-Resistant by the Interagency Grizzly Bear Committee. Despite the name, the committee  is not made up of actual bears. But they do employ them!

To get certified, a container  has to survive 60 minutes of a bear trying to get  break in for a lunch break. Some of the tester bears have been  relocated after having been caught foraging for human food multiple times, sort of an ursine  criminal-turned-FBI-consultant situation. Others have been training to break into  containers since they were six months old.

Hopefully none of the bears’ wild cousins will ever find out that  they’re working for the enemy. Walking the line of creating trash cans that  are accessible to people but not to bears ends up being a race between engineers’  problem solving skills and the bears’. But it's an important race that  can protect both of our species.

And it’s only getting more  important as climate change and urban expansion continues to  reduce bears’ natural foraging area. When we get it right, it does work. Widespread bear-resistant trash can use can, in fact, reduce human-bear  encounters significantly.

And we’re getting better at getting it right. Now, about 50% of cans pass, compared to about 10% when the certification process first started. So hopefully one man’s trash will no  longer be another bear’s treasure, and they’ll both be better for it.

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Thanks for watching! [♪ OUTRO]