We don’t often sing the praises of elephants’ olfactory abilities—it’s their keen memories that tend to get attention—but they nevertheless have an excellent sense of smell. Indeed, a new study has found that the animals are able to sniff out differences in food quantities, shedding intriguing light on one of the ways that elephants might use their noses to navigate their environment.
Previous research has shown that elephants and a variety of other animals—dogs, primates, cetaceans, birds—are able to make quantity judgements using visual cues. But few studies have explored how smell helps animals distinguish between various quantities, like more and less amounts of food. When it comes to elephants, this line of inquiry is important, because the animals’ vision is not as dominant as their senses of hearing, touch and smell.
So a team of researchers led by Joshua Plotnik, a psychologist at Hunter College, set out to test the smelling abilities of six captive elephants at a facility in northern Thailand. Over a series of ten trials, the researchers offered their subjects two buckets containing different amounts of sunflower seeds, a favorite elephant snack. The buckets were covered with lids, but had holes in them so the elephants could smell what was inside. The ratio of seeds in the buckets varied from trial to trial; one bucket pair might have four grams versus eight grams of seeds (a 1:2 ratio), for instance, while another trial featured buckets with eight grams versus 12 grams of seeds (a 2:3 ratio).
“Remarkably, when we put two different quantities in the buckets, the elephants consistently chose the quantity that had more over less,” Plotnik tells Veronique Greenwood of the New York Times.
As the researchers report in Proceedings of the National Academy of Sciences, the elephants were better able to choose the bucket with more seeds when the difference between the seed quantities increased. Changing the quantity of seeds but keeping the ratios the same—for instance, presenting the elephants with four versus eight grams of seeds, and 12 grams versus 24 grams of seeds—did not seem to affect the animals’ success rate.
The team conducted a series of control experiments to rule out various factors that might influence their results. To make sure that the human experimenters were not somehow cuing the elephants towards the larger quantity, for example, the researchers tested a double-blind condition where the experimenters did not know which bucket contained more seeds. They also completed trials with a metal bucket, to ensure that olfactory clues weren’t being left behind on the plastic buckets used in the main experiment. At one point, Plotnik suspected that the elephants might be able to sniff out the larger seed quantity simply because it reached higher in the bucket. “But we raised the seeds up in the bucket so they were at the same level, and the elephants could still tell the difference,” he tells Chelsea Whyte of New Scientist.
As the researchers acknowledge in their report, their study was small and only involved captive elephants; finding out how wild elephants use smell to make quantity judgements could be an interesting avenue of investigation moving forward. But for now, the study highlights the importance of designing experiments that look beyond vision when investigating animals’ cognition. Elephants, the new research suggests, might rely heavily on smell to make important decisions about food availability in the wild.
The researchers also note that their findings could have important implications for mitigating conflicts between elephants and humans. Typically, attempts to keep elephants away from crops involve shutting them out with electric fences or scaring them away with frightening noises. But perhaps, if we can gain a better understanding of how elephants use their noses, they can be lured away by tantalizing smells.