Paraphrased from EurekAlert, new research has just come out from the Chimpanzee Cognition Center at Ohio State University and it is really interesting. It is the first research of its kind to document that raising chimpanzees in a human cultural environment enhances their cognitive abilities, as measured by their ability to understand how to rake. I know it sounds kinda silly, raking chimps but it is a pretty remarkable experiment.

The findings have just been published online in the journal Animal Cognition, under the title, “Raking it in: the impact of enculturation on chimpanzee tool use.”

Three groups of chimpanzees were used to in these pyschological tests. One group has a history of long-term stable, social interaction with humans, labeled the ‘enculturated’ ones. Another group was raised in a sanctuary setting, with only caretaker contact with humans and branded the ‘semi-enculturated’. The last group was raised as laboratory chimps, or ones with limited human contact. The experiments looked at how the chimpanzees used rakes in order to retrieve a fruit yogurt 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 sanctuary chimpanzees chose randomly between the two hybrid tools. The captive laboratory chimpanzees failed both tests, as demonstrated in previously published work.

The authors conclude that the differences in performance between the three groups are directly attributable to the significant effect of level of enculturation. They add that “enculturated chimpanzees may be better at learning within a highly social, interactive context because they have heightened attention to the actions of others.”

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