While humans are divided between right-handed and left-handed, elephants have a preference for which side of their trunk they use. Now scientists have discovered it is possible to determine an elephant’s “trunks” by looking at its wrinkles.
While the pachyderms generally show an almost 50:50 split in terms of which way they prefer to bend their trunks, scientists have found that it is possible to determine an individual adult’s preference.
The team says a left side of its trunk – which scoops up objects to the left side of its body – has more wrinkles and longer whiskers on the left side of its trunk, with whiskers on the right side worn off by more frequent contact with the ground.
“The mustache length difference is large and prominent,” said Dr Michael Brecht, co-author of the study from the Humboldt University of Berlin. “The ripple effect is more subtle, but still significant. This suggests that wrinkle patterns are at least partially use-dependent.”
The discovery is one of a number of revelations about skirt folds made by the team.
Published in the journal Royal Society Open Science, Brecht and colleagues report what they say is the most comprehensive study yet of the lifelong development of trunk wrinkles in Asian and African elephants.
The team studied both the trunks of dead elephants as well as photographs of living elephants and found that the distance between wrinkles on the trunks of adult elephants decreases as they move from base to tip.
Asian elephants have been found to have many more wrinkles at the top of their trunks than African elephants, with further analysis revealing that this is due to a greater number of deep fold-like wrinkles.
Brecht said that wrinkles are thought to make the trunk more flexible – a bit like the folds of an accordion – and added that the theory could help explain why Asian elephants have more trunk wrinkles.
As Brecht notes, African elephants have two finger-like structures on the tips of their trunks, which they use to grasp objects, while Asian elephants have only one. As a result, unlike African elephants, Asian elephants often wrap their trunk around objects around them to grasp.
“For this casing, the hull has to be more flexible, and we think that’s why they have a lot more wrinkles,” said Brecht.
The team found that the number of folds is not equal on both sides of an elephant’s trunk, revealing that this appears to be related to the “stumps” of the animal.
And while elephants are known to have trunk wrinkles at birth, the research sheds light on how they form in the womb.
When the researchers looked at elephant fetuses, they found that between day 80 and day 150 of gestation, the number of trunk folds doubled every 20 days or so, before slowing dramatically.
“Later wrinkles are added slowly, but at a faster rate in Asian than African elephants,” the team said.
Brecht said elephant trunks are highly specialized, adding that their folds are mapped onto neurons in the brainstem.
“The trunk is this insane, wonderful, gripping organ that is very unusual. [It] has more muscle than any other body structure in mammals,” he said. “The only thing that compares to that is the hand.”
