[ad_1]
For a 7,600-pound Asian elephant, simply putting one foot in front of the other can be a high-risk proposition: A trip or fall can lead to serious injuries. “The bigger you are, the harder you fall” said John Hutchinson, an expert in large animal locomotion at Britain’s Royal Veterinary College. “If an elephant falls, it will be in big trouble.”
But scientists knew little about how elephants maintain their stability as they lumber across the landscape. TO new study, published in Biology Letters on Wednesday in Britain, suggests that visual feedback helps elephants time their steps. All it took was Hollywood-trained animals, a pair of enormous blindfolds, and the willingness to carefully unbalance one of the largest land mammals on the planet.
“Our elephants were walking slowly, very slowly, walking very slowly,” said Dr. Hutchinson, co-author of the study. “And they were guided by friends and by their caregivers. Therefore, there was absolutely no risk of them falling. Otherwise, I would never have done the experiment.”
Studies have shown that visual feedback helps humans fine-tune their steps. But it was unclear whether the same principle would hold true for elephants, which are often active in low-light conditions and may rely more on tactile cues and physical sensations to stay upright. And there are animal species that sometimes move without using sensory feedback to adjust their bodies.
“We know that delays in the nervous system and the muscular system can be quite long, especially in large animals like elephants,” said Max Donelan, an expert in the mechanics and neurophysiology of locomotion at Simon Fraser University in Canada, who was no. involved in the study. “There’s a chance they don’t rely much on vision because of these long sensory motor delays.”
To test the importance of vision, scientists investigated what happened when it was taken away: would elephants move differently if they were blindfolded?
“In some ways, to me, it’s an embarrassingly simple experiment,” Dr. Hutchinson said. But he realized it would require a non-negotiable condition: “Some very cooperative elephants.”
So Dr. Hutchinson and his colleague Max Kurz, a neuroscientist at Boys Town National Research Hospital in Nebraska, set out for a California facility that trained elephants for movies, commercials and other types of entertainment. There they studied the movements of four female elephants. The scientists strapped a GPS tracker to each animal’s torso and attached an accelerometer to the right hind leg of all four elephants. The accelerometer would produce a signal each time the foot touched the ground, allowing researchers to track the time it took the elephant to complete a stride.
The trainers then had each of the elephants grab the tail of a friendly guide elephant and walk slowly behind their leader along a 300-foot walkway. In some of the tests, the scientists left the elephants’ vision free. In others, trainers wrapped large pieces of cloth around the elephants’ faces. (Blindfolded elephants sometimes had trouble finding the guide elephant’s tail.)
When the elephants could see, the pace of their strides remained relatively constant. But the bandages seemed to unnerve the elephants, making the rhythm of their strides more erratic.
The finding suggested that when the elephants could no longer see, they had more trouble calibrating the rhythm of their steps. “And then the elephant deviates from what would be more comfortable, perhaps more stable,” Dr. Hutchinson said. In some circumstances, these subtle differences in timing could cause a stumble.
“This indicates that vision plays an important role in these animals not only in knowing where they are walking, but also in controlling the movement of their limbs,” said Dr. Donelan, who also praised the researchers’ experimental approach.
He added: “With elephants, we have to be very careful and we have to be very creative in the type of experiments that are carried out. But they are also the largest living land mammals, so you learn things about how to be big just from them.”
Veterinarians and animal keepers could also use this type of gait analysis to monitor the health of elephants, Dr. Hutchinson said, since erratic gaits show a sign of neurological or muscular problems. “It has the potential to be a practical way to expand our elephant care toolbox,” he said.