Trust defines friendship, and a new study in chimpanzee pals proves it all. This simply points out that friendship built on trust begun centuries ago, dating back to at least the last common ancestor of humans and chimps. This is according to a report published in the Current Biology journal.

Jan Engelmann of the Max Planck Institute for Evolutionary Anthropology and co-author reported in a press release that humans greatly trust their friends with vital resources or crucial secrets. In his study, he together with his co-researchers observed whether chimps exude a similar pattern and show trust specifically towards those people they are closely bonded with. In their findings, they discovered that they do certainly hence the present characteristic of human friendships date back to history, which extends to that of primate social bonds.

The study

Research conducted before revealed that chimpanzees have relationships which pretty much resemble friendships. For example, they do favors ideally towards certain individuals.  In order to ascertain what those relationships were dependent on, Engelmann and Ether Hermann, co-author, studied the interactions of 15 chimps residing in Sweetwaters Chimpanzee Sanctuary in Kenya, for a period of 5 months.

Depending on friendly interactions among a pair of chimps, including feeding together and grooming, the researchers were able to pin-point each chimp’s closest ‘friend’ and ‘not a friend’. Stage two was making the chimps partake in an altered version of the human trust game. They played the game with both their friend and not their friend, going over each match 12 times.

The set-up included a board placed between two participants. A ‘trust rope’ and a ‘no trust’ rope linked to the board determined the kind of food reward the players got. If a chimpanzee pulled the trust rope, the other player was immediately rewarded with plenty of tempting treats that he/she couldn’t share with the chimp that pulled the rope. If a chimp pulled the no trust rope, he/she was awarder not-so-great treats immediately.

There was a win-win outcome with the pulling of the trust rope, which provided the best platform for both participants, only if the first chimpanzee trusted the other chimp to the point of sharing the goodies. As expected, the chimps exhibited much trust when playing the game with a friend. The researchers elaborated that the chimps were notably more likely to willingly place resources at the expense of a partner, hence select a risky but ideally high-payoff option when they interact with a friend as opposed to a non-friend.

They may not hand out Valentine’s Day cards in February, however, they do have friends as studies confirm. Their bondage is similar to that of humans. Although human friendships do not constitute peculiarity in the animal kingdom, Engelmann says other animals such as chimps build close and long-term emotional connections with particular individuals. Such studies reveal more about our relative primates and also offer more insight into the human evolution.