Natural High: Animals that Use Drugs in the Wild

October 26, 2015 | Sarah Tse

Cane toad, Australia
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Humans aren’t the only species that sometimes seek mind-altering experiences.

It turns out animals have vices just like we do. Intoxicating substances usually come from a natural source, and many animals consume these “natural drugs” on a regular basis. While some of these animals have mechanisms to avoid getting intoxicated, a few intentionally seek the psychoactive effects for recreational use.

SEE ALSO: Nature's Zombies: Mind-Altering Infections from Snails to Humans

Alcohol is probably the easiest substance for animals to access, since it forms whenever sugar naturally ferments due to heat and humidity. There are plenty of stories of moose, bears, and birds accidentally eating too many fermented fruits and getting into trouble. It’s like they had those rebellious college years, too.

Vervet monkey with blue scrotum
The vervet monkey shares many traits with human including alcohol use, hypertension, and anxiety. Photo credit: Yoky/Wikipedia (CC BY-SA 3.0)

Vervet monkeys, however, get drunk on purpose. Since their introduction to the Caribbean a few centuries ago, these monkeys have enjoyed imbibing whenever sugar cane crops ferment before the harvest. Researchers have tested their taste for alcohol, and found that 1 in 5 monkeys will reach for spiked sugar water over a virgin cocktail. Unsurprisingly, younger monkeys are more likely to drink, even to the point where they become aggressive or lose consciousness.

If vervet monkeys are the unseasoned freshmen at an animal college party, the pen-tailed treeshrew is a veteran frat bro. Every night it consumes the equivalent of 10 to 12 glasses of wine, in the form of fermented nectar from flowers of the bertram palm. The palm cultivates yeast in its flower buds because a stronger brew attracts more shrews to help spread its pollen.

Pen-tailed treeshrew, Ptilocercus lowii
Caption: The pen-tailed treeshrew could drink you under the table. Photo credit: Joseph Wolf (1820 – 1899)

How does the shrew keep from passing out in a drunken stupor? It converts much of the alcohol into a compound that can be integrated into the process of growing hairs, leaving its blood alcohol concentration at levels that would easily pass a breathalyzer test. This natural protection against inebriation makes researchers think that our own inclination for alcohol may be an evolutionary holdover from the days when our common ancestor ate a more fruit-heavy diet.

Unlike the nectar-beer produced by the bertram palms, many drugs come from toxins that plants have developed as a defense mechanism against herbivores (plant eaters). The coca plant produces cocaine as a natural insecticide, since most insects display a bit more common sense than your average wolf of Wall Street.

The larvae of Eloria noyesi, on the other hand, live life a bit more dangerously. These hardcore caterpillars actually prefer coca leaves over any other food. Cocaine normally causes a high by blocking dopamine transporters, but the caterpillars somehow prevent the cocaine from affecting their neurotransmitters. Their tolerance for the toxin has prompted Colombian researchers to consider using them to destroy illegal coca crops.

Cane Toad. Bufo marinus
The cane toad (Budo marinus) secretes bufotoxin, a strong hallucinogen and a favorite refreshment for dogs. Photo credit: gailhampshire/Flickr (CC BY 2.0)

Even when animals can’t safely metabolize a toxin, they still might eat it just to get high. Veterinarians routinely warn pet owners to keep their dogs and cats from licking toads, as many species secrete hallucinogens from their skin. The internet abounds with stories and videos of pets (and people) that behave abnormally after getting a lick, and some even go back for more. One dog owner reported her Cocker Spaniel’s troubling lapse into habitual toad-sucking, until she mellowed out a bit with age.

The most mundane instance of animal substance abuse is sold at the local pet store: catnip. Once a cat gets a whiff of nepetalactone, a chemical in catnip’s leaves, it acts like any other drug addict and itches for more. Scientists believe nepetalactone mimics normal cat pheromones, which explains their addiction to the stuff.

While recreational drug use isn’t nearly as widespread among animals as it is with humans, these cases show that we share the neurological hardware that enjoys the occasional buzz. Whether it’s with fermented cane juice or slimy amphibians, animal addicts can offer another perspective on the more harmful practices of our own species.

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