You can, if the movie Forrest Gump is to be believed, tell a lot about a person by their shoes. Delightfully, according to a new paper, the same is true of elephants – although, since they’re lacking in the shoe department, you’ll have to direct your gaze a little more… noseward.
That’s right: an elephant’s trunk, probably the most iconic and versatile piece of its anatomy, has a lot to tell us about its owner. You can, it turns out, estimate the animal’s age from its trunk; you can get a pretty good idea of the specific species; you can even figure out how the individual elephant in question prefers to move.
You just have to know what to look for.
How the elephant got its wrinkles
Evolution is nothing if not a problem solver. Not enough fingers to hold your food? Easy: just stretch out one of your wrist bones and use it as a thumb! Your ancestors decided to live in the deep ocean, making it basically impossible to see more than a few meters ahead of you? That’s okay: simply turn your head into a big old echolocation device, beating humans to the invention of sonar by a few million years.
Perhaps one of the weirder substitutions, at least on paper, is found in elephants. Unable to use any kind of fingers or hands to grasp what they want, they instead decided to develop a different appendage: their noses. And despite how ridiculous that concept sounds, it works incredibly well: the elephant trunk is, computational neuroscientist Michael Brecht of the Humboldt University of Berlin told Science this week, “the most unbelievable grasping organ on the planet.”
That’s thanks to a couple of things – or to be more accurate, a couple dozen thousand things. Around 40,000 muscles form what is technically known as a “muscular hydrostat” – a structure made from and supported by muscles, which acts almost like a fluid in its ability to move and compress itself (for a more familiar example, check inside your own mouth: the tongue is also a muscular hydrostat). At the end of the trunk, the animals have either one or two “fingers” that they can use to pinch objects as thin and fragile as a single tortilla chip – though they don’t use them exactly the same way we do, preferring to employ a “suck-and-grab” technique to get what they want.
Other ingenious adaptations are more subtle. There’s one feature of an elephant’s trunk – something so obvious you’ve probably never even noticed it – that Brecht believes is “very underrated”: the wrinkles.
“The trunks of elephants have prominent wrinkles from their base to the very tip,” explains the new paper, on which Brecht is a corresponding author. “But neither the obvious differences in wrinkles between elephant species nor their development have been studied before.”
So Brecht and his colleagues decided to close this gap in the knowledge. “We studied wrinkles on the trunk of Asian (E. maximus) and African (L. africana) elephants,” the paper notes. “We analyzed photographs of live elephants from Zoos and post-mortem samples that were collected in a decade-long effort by the IZW [the Leibniz Institute for Zoo and Wildlife Research, Berlin]. We looked at skin structure in relation to wrinkles using post-mortem specimens and microCT scans. To examine the early development of wrinkles, we studied post-mortem material from fetuses and newborns.”
It was, in every sense, an investigation of elephantine proportions. And pretty quickly, the team started noticing some significant differences between the various samples. Asian elephant trunks, they found, are more wrinkly than African elephants’ by a factor of around 50 percent – possibly an adaptation to make up for having half as many “fingers”, study coauthor Andrew Schulz told Science. Older elephants are, perhaps unsurprisingly, wrinklier than babies; maybe most intriguingly of all, it was possible to tell which individuals were left-trunked or right-trunked based on their particular wrinkle pattern.
Clues to “trunkedness”
Yes, you read that right. Their dexterity and utility aren’t the only ways in which trunks are comparable to human hands: elephants can, in fact, be either left- or right-trunked.
Like humans, “elephant babies are born without [this preference] and will develop a favored side along with their trunk control,” the paper explains – a (hilariously cute) process that takes around two months, rather than humans’ two or so years.
Obviously, this “trunkedness” doesn’t refer to a tendency to use either a left or right trunk, however – rather, a left-trunked elephant is one who prefers to curve their trunk to the left when they wrap around or pick up objects.
Do that enough over the course of your life, and your trunk will start to show the evidence. “We found a difference of 10 percent in wrinkle numbers between the left/right side of the trunk shaft correlating with the individual’s ‘trunkedness’,” the paper notes. “We had one case of an ambidextrous African elephant with no whisker or wrinkle difference, reinforcing our theory of the modification of the wrinkle pattern based on a user-dependent experience.”
The tip of the trunk
Ultimately, there are still many questions to be answered around the elephant’s iconic nose: precisely how it forms in utero; whether trunkedness controls wrinkle formation or vice versa; why the presence of the animal’s thick skin doesn’t interfere with the trunk’s dexterity – all more or less mysterious for now, and difficult to resolve without a lot of time, care, and ethical wrangling.
Still, the new study has certainly shed some intriguing light on the intricacies of the trunk – and just how much of its success may be due to its wrinkly cover.
“Wrinkles and creases improve the ability of soft biological materials to bend,” the authors conclude, noting that “trunk wrinkles and their unique form in African and Asian elephants could contribute to the phenomenally flexible actuation of trunks.”
“Our analysis extends earlier work on the wrinkle structure of elephant skin,” they write, “and gives insights into the development of the largest extant land mammals.”
The paper is published in the journal Royal Society Open Science.
