For a 7,600-pound Asian elephant, simply putting one foot in front of the other can be a high-stakes proposition: A trip or fall can result in severe injury. “The bigger you are, the harder you fall,” said John Hutchinson, an expert on large animal movements at the Royal Veterinary College in Britain. “If an elephant falls, it’s in big trouble.”
But scientists know little about how elephants maintain their stability as they traverse the landscape. A new study, published in Biology Letters on Wednesday in Britain, suggests that visual feedback helps elephants time their steps. All it takes are Hollywood-trained animals, a set of oversized blindfolds and a willingness to — carefully — push one of the largest land mammals on the planet slightly off balance.
“Our elephants are slow, very slow, a really slow walker,” said Dr. Hutchinson, a co-author of the study. “And they were guided by friends and their handlers. So there is absolutely no risk of them falling. Otherwise, I would not have done the experiment.”
Studies have shown that visual feedback helps people fine-tune their steps. But it’s 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 on their feet. And there are animal species that sometimes move without using sensory feedback to adjust their bodies.
“We know that the time delays in the nervous system and the muscular system can be very 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, which was not involved in the study. “They tend to be less visually dependent because of this long sensory motor delay.”
To test the importance of vision, scientists investigated what happened when they removed it: Do elephants move differently if they were blindfolded?
“In a way, for me, it’s an embarrassingly simple experiment,” said Dr. Hutchinson. But this would require a non-negotiable condition, he realized: “Some very cooperative elephants.”
So Dr. Hutchinson and his colleague Max Kurz, a neuroscientist at Boys Town National Research Hospital in Nebraska, went to a California facility that trained elephants for movies, commercials and other forms of entertainment. There, they studied the movements of four female elephants. The scientists fitted a GPS tracker to the body of each animal and fitted an accelerometer to the rear right leg of all four elephants. The accelerometer will produce a signal every time the foot hits the ground, allowing the researchers to track the time it took the elephant to complete a step.
The trainers then instructed each of the elephants to take the tail of a friendly elephant guide and slowly step behind its leader along a 300-foot path. In some of the tests, the scientists left the elephants’ vision unobstructed. In others, trainers wrapped large pieces of cloth over the elephants’ faces. (Blinched elephants sometimes have difficulty finding the guiding elephant’s tail.)
When the elephants saw, the timing of their steps remained relatively constant. But the blindfolds seemed to throw off the elephants, making their steps more mistimed.
The finding suggested that when elephants lose sight, they have a harder time calibrating the timing of their steps. “And so the elephant deviates from what would be the most comfortable, perhaps the most stable,” said Dr. Hutchinson. In some cases, these subtle differences in timing can cause stumbling.
“This suggests that vision plays an important role in these animals for not only knowing where they are walking, but also controlling the movement of their feet,” said Dr. Donelan, who also praised the researchers’ experimental approach.
He added: “With elephants, we have to be very careful and you have to be creative about the kind of experiments you do. But then they’re also the largest living mammals on earth so you learn things about being big. only from them.”
Veterinarians and zookeepers can also use this type of gait analysis to monitor elephant health, Dr. Hutchinson, with improperly timed steps showing signs of neurological or muscular problems. “This has the potential to be a practical way to add to our elephant care toolbox,” he said.