Fashion, Theft and Grudges: 5 Animals That Act Like Humans

Did you know that Adélie penguins can turn to prostitution? As it happens, quite a few animals act in ways that seem oddly... human. Read on for some of my favorite examples, such as how:

• Dolphins pass pufferfish for a chemical high
• Capuchin monkeys can understand currency
• Crows hold and pass on grudges
• Whales wear wigs and hats
• Penguins turn to theft and prostitution

Dolphins Pass Pufferfish for a Chemical High: It's not that hard to picture a group of folk passing drugs between themselves - things get a little weirder when those folk are dolphins and the drugs are a pufferfish!

Pufferfish may look fairly harmless, but many of them ooze deadly tetrodotoxin to keep themselves safe. You wouldn't think this would make them appealing, but pods of dolphins have been seen passing one of the traumatized fish between themselves to get high.

The BBC even captured footage of the marine mammals harassing a poor puffer, prodding it, holding it in their mouths or even surfacing to throw it above the water. One thing the dolphins didn't do was swallow. Instead, they lightly chewed the pufferfish to get a taste of the tetrodotoxin - and those who indulged showed signs of intoxication!

Capuchin Monkeys Can Understand Currency: In 2005, Yale researchers introduced the concept of money to capuchin monkeys. It didn't take them long to descend into vice.

The experiments were set up using a token economy. Researchers would give the animals a token, then swap the token for a bit of food. Eventually, the capuchins realized that a token could be swapped for something they actually wanted. Once the monkeys had grasped this idea they were allowed to enter a sub-enclosure (set up a bit like a market) where they were given tokens to spend on a choice of foods.

A number of things were revealed by the buying habits of the capuchins. First off, the monkeys showed a personal preference for different foods and (unsurprisingly) would buy the one they liked most. Secondly, if the food they liked suddenly dropped in value (halving the portion per token, for example) the canny capuchins would buy less of their favorite food and more of the better value option!

The study also featured first known bank heist by a monkey. One day a capuchin grabbed the tray of tokens, hurled it into the enclosure and fled after it rather than taking part in the experiment. Not only did this cause chaos for the researchers who had to buy the tokens back, one of the newly enriched monkeys gave a token to another capuchin in exchange for sex. As if to underline the transactional nature of this arrangement, the token was swapped for a grape moments after the deed was done.

Crows Hold and Pass On Grudges: Did you know that crows can hold a grudge? As a group of Washington researchers found out, the American crows of Seattle certainly can.

A team from the University of Washington caught and tagged crows at several nearby locations, all while having donned plastic character masks. The trapped birds were understandably upset by this, but it also seemed to alarm the local crow populations - they circled the trapping sites, making alarm calls all the while.

Shortly after releasing the birds, researchers found that around a quarter of the local crows would scold anyone wearing one of the character masks with calls and aggressive gestures - even if that bird hadn't been one of the captives. This affronted behavior wasn't short lived - it was actually passed on to new generations of crows, with birds 1.2km from a capture site scolding (or even mobbing) anyone wearing the masks half a decade after the initial experiment.

A similar thing happened to Won Young Lee of Seoul National University. Each year, the university conducted a survey of the campus black-billed magpie population. Lee had previously handled the nests as part of his experiments - and the magpies didn't remember him fondly.

The birds followed and scolded him while he tried to conduct the survey, though they didn't seem to care about another researcher accompanying him. The two even swapped hats in an ultimately fruitless attempt to fool the birds.

Whales Wear Wigs and Hats: In 1987, scientists observed a female orca swimming around with a dead salmon on her head. Within a matter of weeks, the rest of her pod had taken up the bizarre fashion statement.

The salmon hats were only in fashion for around a year, though they seemed to make something of a comeback in 2024. Nobody really knows the reason for the trend - one possibility is that it was a way for these toothed-whales to carry some food with them (orcas have been seen clutching meat beneath their flippers) but if that's the case, why did it fall back out of fashion?

It's not just the toothed-whales that have hats either. Humpback whales in particular are known for "kelping" which involves playing with seaweed or wearing it like a wig. The behavior can be found in humpbacks from both the northern and southern hemispheres, with the whales wearing their wigs in the same way despite being from opposite sides of the world.

As for why humpbacks kelp, they might simply be using the seaweed as an abrasive rub. Much like a human using a flannel, the seaweed could help remove muck, parasites and dead skin. It could also just feel nice!

Penguins Turn to Theft and Prostitution: You might be impressed with the capuchin's swift descent into vice, but they are rank amateurs compared to the sordid lives of Adélie penguins.

First, let me set the scene. The penguins nest on cold, rocky soil in the Antarctic, laying eggs in nests made of pebbles. It doesn't sound comfy, but there's a good reason for the choice of material - any time temperatures rise, meltwater can run around and through the nests. If they were made of twigs and feathers, the nests would soak up icy water and potentially kill chicks before they could even hatch. A substantial stone nest can keep the eggs high and dry, meaning that good pebbles are a prized commodity.

Some penguins turn to theft in an attempt to get enough stones. After all, it is much easier to grab a pebble from the unattended nest next door than go searching. This approach isn't without risk though - if the nest builder catches the thief, they can expect to be chased and viciously pecked.

An alternative option available to female Adélie is to turn to prostitution. Females have been observed wandering from their own nests to flirt with unattached males. If the male responds to her interest, she hops up on the nest and allows the male to mate with her before grabbing a pebble and returning home.

It should also be noted that some Adélie penguins combine theft and prostitution - after flirting, they simply grab a stone and scamper off, leaving a bemused male behind!

Sources and further Information:

• Thrilling BBC footage shows dolphins playing lethal game of catch with a deadly pufferfish - and getting high in the process
• How Basic Are Behavioral Biases? Evidence from Capuchin Monkey Trading Behavior
• The Experiment That Taught Monkeys How to Use Money | Freakonomics
• Social learning spreads knowledge about dangerous humans among American crows
• Magpies Not Only Recognize Humans, But Scold Them Too!
• For Orcas, Dead Salmon Hats Are Back in Fashion after 37 Years
• What is ‘kelping’? Why whales are making hats out of seaweed
• Criminal Penguins - Frozen Planet - BBC
• Mating in a Material World