How an Elephant’s Wrinkles Reveal Whether It Is Right- or Left-Trunked

Until recently, scientists believed that wrinkles on the trunks of elephants simply formed over time, like the wrinkles on human faces. But after a team of experts noticed that even calves have wrinkly proboscises, they realized the wrinkles might play a bigger role in this animal’s iconic appendage than most people realize.

Wrinkles can even reveal whether an individual elephant prefers to bend its trunk to the right or the left, according to the new study published in the journal Royal Society Open Science on Wednesday.

“We think these wrinkles are very underrated,” Michael Brecht, co-author of the paper and a computational neuroscientist from Humboldt University of Berlin, tells Science’s Sara Reardon.

Trunks are not just glorified noses. The boneless appendage is packed with muscles, allowing elephants to do everything from peeling bananas to picking up objects to making trumpeting noises. A single trunk contains around 40,000 muscles—a shocking quantity compared to the human body, which houses somewhere between 600 and 700 muscles in all.

Science News’ Susan Milius even goes as far as to say that elephant trunks are less nose and more “sci-fi space tentacle.” A wrinkly sci-fi space tentacle, one might add.

To understand the development and purpose of trunk wrinkles, a team of scientists focused on Asian and African elephants. They studied live individuals in zoos and tissue samples in museums, and they combed through photographs, both of adult elephants and of fetuses in the womb.

It's awesome to see the elephant wrinkle paper out today in @RSocPublishing! Thank you to @NewsfromScience for covering - read all about how elephants develop their wrinkles - paper linked in comments below https://t.co/T5x0NHCX9W

— Andrew K. Schulz (@SchulzScience_) October 9, 2024

By aligning the photographs chronologically, scientists confirmed that elephants, like humans, gain more wrinkles with age. However, they also noted that elephant trunk wrinkles form before birth, which suggests a specific purpose for the creases. While human babies often have random folds of skin because there is simply too much of it, per Science, trunk wrinkles in elephants might be a necessary characteristic of their development, supporting flexibility for movement and lifting objects.

The comparisons with humans don’t end there: The scientists recognized that elephants have right or left “trunkedness,” just like we can be left- or right-handed. A right-trunked elephant is more likely to curl its trunk to the right to pick things up, while a left-trunked elephant would prefer to bend it the other way. In the study, the groups of elephants studied each had an almost even split of right- and left-trunkedness, per the Guardian’s Nicola Davis.

This tendency results in more wrinkles on the right side of the trunk in right-trunked elephants, and on the left side of the trunk of left-trunked elephants. It also changes their whiskers: Elephants that consistently curl their trunks to the right scuff the whiskers on the left side against the ground when picking up an object, and vice versa. As a result, their whiskers are significantly shorter on the opposite side to the curling direction.

“The whisker length difference is big and prominent,” Brecht tells the Guardian. “The wrinkle effect is more subtle, but still significant. It indicates that wrinkle patterns are at least partially use-dependent.”

Future long-term studies might answer a chicken-and-egg type of question: Which comes first, the trunkedness or the wrinkles? It might be that trunkedness is controlled by the brain and causes asymmetrical wrinkles as the elephants handle more objects, John Hutchinson, a biologist at the Royal Veterinary College in England who wasn’t involved in the paper, suggests to Science. But he adds that it might also be the other way around: that asymmetrical wrinkles present at birth make it easier for an individual to develop trunkedness in a specific direction.

The team also reported on wrinkle differences between Asian and African elephants. On average, Asian elephant trunks have 126 major wrinkles on the upper side, whereas African elephants have around 83. Assuming that wrinkles help with trunk flexibility, this would be consistent with other differences between the species—namely, that African elephants have two finger-like appendages at the ends of their trunks that allow for small pinching maneuvers, while Asian elephants have just one. In other words, Asian elephants might need more overall trunk flexibility, provided by their higher number of wrinkles, than African elephants do.

As fascinating as it is to learn more about these creatures, the study could also hold implications for fields beyond biology. Study co-author Andrew K. Schulz, a mechanical engineer and biophysicist at the Max Planck Institute for Intelligent Systems, has, in the past, examined the skin on elephant trunks to uncover how it stretches. He hopes those results, along with the new research, will be useful to the development of soft robots for disaster responses, per Science.

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.