The researchers observed a Visayan acne pig family using sticks to dig and build nests, evidence that pigs are capable of using tools.
Co-author Meredith Root-Bernstein, a conservation ecologist, stumbled upon this at the zoo in Paris, where she witnessed an adult acne pig named Priscilla digging soil with a stick in her mouth.
"It took some leaves, moved them to another spot on the mound and dug a little with the nose," she wrote in her observations. "At one point, he picked up a flat piece of bark about 10 cm x 40 cm lying on that mound and held it in his mouth, using it to dig, lift and push the soil back, quite strongly and quickly. " she described.
In 2015, 2016 and 2017, Root-Bernstein visited Priscilla with a team of researchers to see how Priscilla and other pigs responded to the tools.
Visayan acne pigs are observed at a zoo in Paris.(Photo: Meredith Root-Bernstein).
According to research in the journal Mammalian Biology, the pigs did not do much with the equipment during the first visit, but in 2016, Priscilla and its children moved the stick to dig and build nests.
Billie boars also dug with a stick, though its efforts were more "clumsy" than that of family members, the researchers wrote.
In the 2017 test, Priscilla once again used earthworks 7 times to create a big hole.
However, the study notes that digging with a stick in the mouth is less effective than digging with a nail or a muzzle. The researchers said pigs could see the use of the tool as a reward that makes them "feel good".
It can also be a behavior arising from a physical defect. Or perhaps this behavior is really beneficial for building a team that scientists don't yet know why.
According to research, Visayan acne pigs live in family units and like children, they learn from each other. Therefore, the use of tools may have spread in Priscilla's family.
Only a few species have been discovered using tools to support their lives. Primate species such as chimpanzees and orangutans use them to find food. But this is something unheard of in pigs.
In addition to discovering the intellectual ability of pigs, the study also reveals clues about how cognitive development and the way the body relates to the environment, Root-Bernstein told CNN.
"We may think that only humans manipulate the environment to influence their own lives, but in different ways, many other species do this," she said.