Chimpanzees in captivity can learn how to use tools on their own to dig for food, a trait initially thought to be unique to humans.
A team of researchers from the University of Oslo has observed 10 chimpanzees at an island enclosure in the Kristiansand Zoo in Norway. Of the 10 chimpanzees, eight were born in captivity. None of the chimpanzees that were chosen to participate in the experiment have previously exhibited excavation behaviors.
They published their findings in the journal PLOS One on Wednesday, May 15.
Chimpanzees Use Tools To Dig Food
During the experiment, the researchers dug five holes on the ground and placed fruits in them. They initially left the holes open to let the chimpanzees know that there are food in them. They later on covered each hole.
The researchers also initially provided ready-made tree stick and bark tools for the chimpanzees to use. However, in a second experiment, tools were not provided.
They reported that nine out of 10 chimpanzees successfully dug out food that has been buried at least once during the course of the experiment. Eight out of 10 of them chose to use tools rather than their bare hands to excavate fruits.
During scenarios where tools were not provided, the researchers observed that the chimpanzees created their own using vegetation available around the island. The study also noted that the primates preferred shorter sticks to excavate than longer ones. The chimpanzees also reused their tools.
In addition, the researchers noted that the chimpanzees tend to take turns excavating holes that they know have food in them. The group even shared food among each other once they retrieved the buried fruits.
Looking Back Into The Past
Previous studies have previously documented wild chimpanzees and bearded capuchins were capable of using tools to excavate for underground food, including corms and tubers. For this experiment, the researchers hope to study the behaviors that chimpanzees in captivity would develop as they learn to use tools to forage for food.
The researchers also believe that, by observing chimpanzees, scientists could learn more about the lives of early hominins and how they learned how to use simple tools to harvest food. Tool-assisted excavation of plant underground storage organs might have played a role in hominin evolution.
While they cautioned against looking at modern apes as living fossils or stand-in for hominins, the researchers speculated that human's ancestors might have worked out how to use tools to excavate food in the same way as the chimpanzees.