April 12, 2017 at 5:00 AM
Humans have been handing mirrors to animals since at least the early 1800s, when a young Charles Darwin proffered a polished glass to a pair of orangutans at the London Zoo. "Both were astonished beyond measure at looking glass, looked at it every way, sideways, & with most steady surprise," Darwin wrote in his notebook. More than a century later, psychologist Gordon G. Gallup codified what became known as the mirror test, when in 1970 he demonstrated that chimpanzees could recognize their own reflections. Only a handful of other animals have passed the mirror test: apes, dolphins, orcas, Eurasian magpies and an Asian elephant named Happy.
"There are many camps that argue about what this all means," Joshua Plotnik, a visiting psychology professor at the City University of New York's Hunter College and founder of the nonprofit Think Elephants International, told The Washington Post. Some scientists view a successful mirror test as a sign that animals have self-awareness, linked to complex concepts like empathy. And if an animal can't pass the test, well, then it simply can't be self-aware.
Plotnik, who worked on Happy's mirror test, took a more diplomatic approach. It is more likely, he said, that self-awareness exists on a continuum, with varying levels of animal understanding. What's more, for some species the mirror test simply is a bad exam — particularly for those that rely less on visual senses, unlike humans or magpies.
This led Plotnik and a colleague, Rachel Dale, a graduate student at the University of Veterinary Medicine, Vienna, to develop a test from the perspective of an elephant. Vision is not the primary sense of an elephant, Plotnik said. "Elephants probably 'see' their world with their ears and trunks," he said.
The scientists modified a test given to human infants. When children are between 18 and 24 months old, they can pass the mirror test. This is also the age when humans develop what is called "body-awareness," which means they recognize that their bodies have a relationship with the environment.
In tests of human body awareness, children are told to push a shopping cart toward a caregiver. There's a trick: Tied behind the shopping cart is a mat. The children begin the test standing on the mat, which prevents them from pushing the cart forward. To be successful, children have to realize their own bodies are obstacles. Children older than 18 months figure out that they should step off the mat and steer the cart from the side.
As Plotnik and Dale wrote Wednesday in the journal Scientific Reports, elephants do something remarkably similar. "They have clearly recognized that their body can get in the way of something," Plotnik said.
To test the elephants, the scientists traveled to Thailand, where they posed a problem to 12 Asian pachyderms. The elephants had to pick up a stick and hand it over to their mahouts, or trainers. In the experimental condition, the scientists tied the stick to a rubber mat. As in the study of human children, the elephants began the test standing on the mat. The animals "very quickly" realized that they had to step off the mat to hand over the stick, Plotnik said. During trials when the stick was unattached to the mat, the elephants rarely bothered to lift their feet.
This demonstration of an elephant's body awareness was different, Plotnik said, than a cat licking the fur attached to its haunches. That behavior may not show any thought more labored than, say, a reaction to an itch. The problem solving in the new study was a few notches more complex. If an elephant lacked an awareness of its immense body, Plotnik argued, the animal would keep trying to exchange the stick while standing on the mat. Or the elephant would simply give up.
"I'm not sure that this test is nearly as complex as the mirror test," Plotnik said. But, taken together with the mirror test, the stick experiment added "another point to the spectrum of self-understanding" for elephants. This was far from the only additional marker of complex elephant behavior: In 2014, Plotnik and biologist Frans de Waal determined that the animals will console other distraught elephants. It has been suggested, too, that elephants mourn their dead.
The psychologist said his motivation was not to simply gauge elephant intelligence. Asian elephants are not poached for ivory at the rate of their African relatives. But they come into conflict with people just the same, as growing human populations in Asia encroach upon elephant habitat. Some local communities have tried scaring Asian elephants away with firecrackers or electrical fences, to limited success.
Those are human solutions, Plotnik said, to a problem that also involves another intelligent species. He said his research could inform what we know about elephants' need for space, for themselves as well as their family groups.
"The more we understand about elephant behavior," he said, "the better we will be able to come up with conservation strategies that work."