Okay, so you know how we’re always being told animals are “just animals”? Like, they eat, sleep, and do the National Geographic version of dating? Well, they’re wrong. Because the long-tailed macaques of Bali just proved once again that Mother Nature is full of surprises—and they’re not the PG kind.
Picture this: You’re on vacation in Bali, sipping coconut water and soaking in the serene beauty of Uluwatu Temple. Then, out of the corner of your eye, you spot a monkey doing something very unholy with a rock.
Now, before you clutch your pearls or laugh hysterically, let’s break this down.
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We’ve all heard of animals using tools; chimps cracking nuts, crows bending wires, octopuses carrying coconut shells like tiny bodyguards. But this? This is next-level monkey business.
Researchers observed long-tailed macaques in Bali’s Sacred Monkey Forest rubbing, tapping, and ahem grinding stones against their genitals.
Wait, what?
So, how did we get here? Why are these monkeys turning innocent pebbles into their personal pleasure gadgets? And most importantly—who was the first monkey to try this? Too many questions.
Let’s talk monkey business
Researchers from the Udayana University in Bali and Leipzig University in Germany observed this behaviour in female long-tailed macaques who live around Uluwatu Temple. These monkeys are already known for their intelligence, boldness, and occasional talent for pickpocketing unsuspecting tourists.
But what scientists found in this study took things to a whole new level.
Female macaques were observed rubbing small stones against their genitals, repeatedly, deliberately, and often for 20 seconds or more
According to another study published in Ethology, these little guys have been spotted engaging in what scientists politely call “stone-assisted masturbation.”
Yes, that’s the official term. No, we’re not making this up.
Here’s how it goes down: A monkey picks up a smooth stone, sits in a relaxed position (we’re talking full Netflix and chill vibes), and starts rubbing it against their genitals. Sometimes they tap it rhythmically, other times they go full DJ on it—whatever works, we guess.
And before you ask, yes, both males and females do it.
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The science behind the shenanigans
Now, before you dismiss this as “just monkey madness,” here’s why this is fascinating for science.
Tool use in animals is a major sign of intelligence. It shows planning, experimentation, and an understanding of cause and effect. We’ve seen chimps use sticks to fish out termites, crows craft hooks from twigs, and now? We’ve got macaques turning stones into pleasure devices.
This behaviour also touches on another rarely discussed topic in animal research: sexual behaviour for pleasure, not just reproduction. For a long time, science tiptoed around this idea, focusing mainly on survival instincts. But now, we’re learning that many species, including dolphins, bonobos, and apparently Balinese macaques, engage in intimate behaviours for enjoyment.
Why are they doing it?
The researchers believe this stone-play behaviour is linked to a mix of curiosity, intelligence, and boredom. These macaques live in a relatively safe, well-fed environment with very little stress. Uunlike their cousins in the wild who are too busy foraging or avoiding predators, these Bali monkeys live a comfortable life.
So, with lots of free time and a sharp brain, they start experimenting with rocks.
It’s like what happens when humans get too comfortable: we invent TikTok trends, unnecessary kitchen gadgets, or entire reality shows. The macaques? They invented the stone stimulator.
What’s even more interesting is that this behaviour isn’t random. The monkeys specifically select certain stones—smooth ones that fit easily in their hands. That’s intentional tool choice. They’re not just picking up any rock, they’re shopping for the rock.
Indeed, animals, especially primates, are way more emotionally and cognitively complex than we often give them credit for.
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