So how can you test hyenas’ intelligence?
First, we tried sitting our hyenas down and giving them IQ tests. Unfortunately, they couldn’t hold the pens, and they ended up eating the test booklets. Back to the drawing board.
Seriously though, in order to be effective, our test had to meet a few criteria. First of all, it had to be hyena-proof. It needed to be something our hyenas couldn’t destroy, consume, or drag away.
The test also had to be something that, even with their limited dexterity, hyenas could manipulate in some way to “solve.”
Finally, the test had to represent a “novel task,” which is scientist-speak for “a challenge the hyenas have never seen before.” This way, we know the hyenas aren't just relying on some skill they already have.
Luckily, clever grad student Sarah Benson-Amram came along and developed a test that meets all these criteria. Called a “puzzle box,” it’s based on an invention by psychologist E.L. Thorndike.
Essentially, it’s a big box made of rebar (and when I say “big”, I mean “BIG…” this thing weighs about 75 pounds). The box has a swinging door that closes and locks with a sliding latch. We put a piece of meat inside the box as an incentive, close and lock the door, and present it to a hyena. Their task is to figure out how to get to open the box and get to the meat inside. Just like a Rubik’s cube or Sudoku puzzle is a brainteaser for us, the puzzle box is a way to test hyenas’ problem-solving abilities.
My favorite thing about watching hyenas interact with the box is the multitude of strategies they employ. Some bite the box; others dig underneath it. A few flip and tumble the box. Some decide that an aerial view will help, so they get on top of the box and peer down. Many hyenas try the “If I lie here and stare at it long enough, it will open” strategy. Unfortunately, I haven’t seen this one work yet.
Sarah spent an amazing amount of time and effort developing the box and working out the kinks. During Sarah’s research, 9 Mara hyenas (out of 58 who tried) opened the box. On average, a hyena needed to work on the box three different times before they could open it. One smarty-pants, Snaggletooth, got so good at the task that he was able to open the box in 3 seconds; Kent, shown below, could do it in 5 seconds.
I'm now doing some work with the box here at Serena. While all this just the tip of the iceberg, it’s certainly a promising – and interesting – way to look at animals’ intelligence.