Human interaction and stimulation enhance chimpanzees’ cognitive abilities, according to new research from the Chimpanzee Cognition Center at The Ohio State University. The study (1) is the first to demonstrate that raising chimpanzees in a human cultural environment enhances their cognitive abilities, as measured by their ability to understand how tools work. The findings have just been published online in the Springer journal Animal Cognition.
The scientists compared three groups of chimpanzees: one with a history of long-term stable, social interaction with humans (‘enculturated’); a group raised in a sanctuary setting, with only caretaker contact with humans (‘semi-enculturated’); and another group raised under more austere captive conditions (laboratory chimpanzees). The experiments looked at how the chimpanzees used rakes in order to retrieve a fruit yoghurt reward. The overall study examined not only whether the chimpanzees understood the properties of the tool, but also whether they understood the reasons why the tool worked.
The researchers gave the animals access to small rakes with either a rigid wooden head or a flimsy fabric head. Both enculturated and semi-enculturated chimpanzees correctly chose the rigid rake which enabled them to obtain the reward, indicating that both of these groups understood the physical properties of the two different rakes.
The researchers then presented the same two groups with two identical ‘hybrid’ rakes. Each rake head had a rigid side made of wood (functional) and another side made of flimsy cloth (non-functional). The reward was placed in front of the rigid side of one rake, and in front of the flimsy side of the second rake. The animals who picked the rake with the food reward on the rigid side demonstrated that they understood the causal principles behind the functionality of the rake.
The enculturated chimpanzees successfully selected the functional rake, while the sanct