New Research Finds Wild Pigs Using Tools

In October of 2015, at a zoo in Paris, ecologist Meredith Root-Bernstein was watching a family of pigs when she saw something she had never seen before.

One of the Visayan warty pigs picked up a piece of tree bark with its mouth and started using it as a tool to dig, pushing the soil into the nest it was building. Root-Bernstein, who is a National Geographic researcher, looked up tool use in pigs, but “there was nothing.”

So, she and her colleagues returned frequently, hoping to see that behavior again but were unsuccessful. She hypothesized the behavior was related to the animal’s nesting. Visayan typically nest every six months. Sure enough, the following spring, the colleague had returned to the facilities to record three of the four pigs using tools to build their nests, which is a pit full of leaves.

Using tools is not a strictly-human ability. In fact, the tool using club consists of other types of apes, elephants, dolphins, sea otters, crows, and even octopuses, among others. However, pigs have never been considered a part of this group, including the 17 species of wild pigs and domestic swine. This was originally surprising to Root-Bernstein, given the relatively high intelligence of the Suidae family.

Despite this, wild pigs aren’t very well-studied, and most species are endangered or critically endangered. This lack of population means it’s hard for scientists to study them.

For several visits, Root-Bernstein and her colleagues videotaped and studied the wild pigs in their enclosure. At one point, the team placed four spatulas in the enclosure, thinking that the pigs might prefer more easily wielded tools. However, one spatula was used twice, and that was it.

The team noted that the pigs, especially the mother (Priscilla), would always use the tools in the middle of their nest-building process. The consistency of the behavior, plus the fact that the tools could actually physically move the dirt, met the scientific definition of tool use.

The scientists think Priscilla might have learned the behavior herself and then taught it to her family.

Root-Bernstein does admit that her data set is very small and the fact that the animals are captive could have had an effect on their behavior. But, she does add that most captivity-induced behaviors are marked by repetitive frequency, like pacing or hair pulling. This case only occurs two times a year.

Fernando Gutierrez, president of the Philippine conservation nonprofit Talarak Foundation, Inc., agrees with Root-Bernstein when she says that it is very possible that wild Visayans use tools. In fact, Gutierrez has seen wild pigs do something completely unrelated but equally as interesting.

According to Gutierrez, a wild group of Visayans were approaching an electric fence and pushing rocks towards it to test if it was on. When “the rocks make contact, they would wait for the clicking sound or lack thereof,” he said via email. “Clicking means the wires are hot, and they will back off and not cross; no sounds mean it is safe to investigate what’s beyond the wire.”

For any and all scientists that study animal cognition, this has been a major development. If not relevant to their work, it has at least been intriguing. It offers insight into the minds of animals, as well as into the evolution of intelligence such as our own. Tool use is an ability that all of the smartest animals have and it turns out we may have been underestimating our Suidae friends. It raises these questions: what else have we been underestimating? If pigs are smarter than we’ve been giving them credit for, are there other animals that might have also been overlooked? Or is this evidence of the development of a completely new ability to pigs? It being a change in cognitive ability on an intergenerational level, is this evidence of evolution at work?