Some chimps and gorillas were given a long vertical tube with a peanut at the bottom. To reach the treat, the primates realized they had to add water to the tube...and one chimp came up with a uniquely gross solution.
The basic experiment was meant to test the chimps' ability to think strategically. The tube was too long and narrow for their fingers to reach the peanut, so they had to come up with a way to make the peanut come to them. To help them along, the chimps and gorillas were given a water dispenser, and there was already a small amount of water in the tube.
The researchers' hope was that the primates would figure out they needed to take water from the dispenser in their mouths and then spit that water into the tube, thus raising the water level. But they didn't count on one chimp who played by his own set of rules.
As it turns out, none of the five gorillas tested in the study were able to work out the solution, but 14 of the 43 chimps were able to do it. Lead researcher Dr. Daniel Hanus of the Max Planck Institute for Evolutionary Biology explains what's so remarkable about the chimps' work:
"You cannot explain it by trial-and-error learning. They weren't just spitting water around the room and some fell in by accident. Instead, they were standing in front of the problem, trying to work out the solution - at first by trying to use their fingers, or trying to break it. But some, then went to the drinker and got the mouthful of water and came back and spat it directly into the tube, and a few did it enough times to get the peanut. I think it is quite impressive - I call it insightful behavior."
To put this in perspective, when the researchers repeated the experiment with various young children, six- and eight-year-olds were only barely able to outperform the chimps, and four-year-olds actually did slightly worse at figuring out the solution than their primate counterparts.
But enough about all that useful data about primate reasoning ...what about the urinating chimp? Dr. Hanus recounts the inspiring story:
"He was spitting water into the tube, then got frustrated. So he started peeing and then he realised: 'Wait a minute, if I move in that direction, that fills up the tube'...He seemed like he understood. He was like: 'That's cool, this helps me'."
It goes without saying that the chimp didn't think twice about eating a peanut soaked in its own urine. You know, if the apes ever do rise up and enslave humanity, now we'll know why. They just want it more.