'Tinder for orangutans': Zookeepers hope better dates for apes will lead to more sex

Dutch primatologists are designing a matchmaking experiment for orangutans that will work in much the same way as the dating app Tinder. The efforts are in response to a plea from zookeepers for a way to improve the success of breeding programmes for the endangered species.

Orangutans are solitary for most of their lives, and tend to be quite fussy about who they mate with. As a result, transfers of orangutans between zoos to encourage breeding too often do not result in a baby orangutan. The international transfers can be a stressful experience for the animals and a long way to go for a bad date.

Researcher Mariska Kret of the University of Leiden in the Netherlands is working to understand how orangutans react to pictures of potential mates, to predict the likely success of a transfer from one zoo to another.

Attracting attention

Kret had the idea for the experiment when zookeeper Thomas Bionda from the Apenheul primate park in the central Netherlands gave her a call to tell her about a female orangutan called Samboja, for whom they were struggling to find a mate.

"I immediately thought about psychological experiments that are usually used in humans to measure attention or interest or associations with certain pictures," Kret told IBTimes UK.

"I thought maybe we can use that and design to build a solid method that could help to get insight into the preferences of these animals – which individuals are they attracted to, which do they look at, which ones evoke positive behaviour?"

Kret and her colleagues started the experiments on orangutans a few days ago. The initial stage is to see which pictures of orangutans – all real potential mates in other zoos – grab an ape's attention.

The orangutans are shown two images of orangutans on a screen, left and right, which then disappear. Then a black dot then appears on either the left or the right hand side of the screen. From previous experiments with bonobos, the researchers know that if the dot appears on the side the ape was paying more attention to, they tend to press the dot more quickly, as their attention is already focused on that part of the screen.

"We also know from studies in humans that the things that attract immediate attention are the most biologically relevant, salient stimuli, such as images of attractive potential partners."

Other experiments to assess an orangutan's interest in a potential partner include eye-tracking studies to follow the ape's gaze and thermal imaging, to measure how aroused they become while viewing the image.

A date for Samboja

The orangutans at Apenheul will also be involved in wider experiments to understand emotions and sexual arousal in apes. It's hoped that the experiment can be rolled out to other zoos and primate centres to boost international breeding efforts.

"But right now the urgent question is to help Samboja to select a male," said Kret.

When they find out who might take Samboja's fancy, Kret and her colleagues hope to collaborate with the zoos housing the potential mates to see if the feelings are mutual.

"Attraction works both ways right, so we will also have to do something with potential males. She might be interested but it has to work both ways."

Amorous apes

These experiments have all been done on bonobos before, a group of apes famously enthusiastic about mating, but it's not yet clear whether solitary orangutans like Samboja will react in the same way.

However, some other females do seem to have taken a liking to the experiment. A female orangutan called Sandy has shown a particular interest.

"She was really happy with the computer screen. She got very, very excited the first time she sat behind it."

Kret's colleague Evy van Berlo had been setting up the equipment for Sandy when the anticipation appeared to get the better of the ape. "Evy was taking a bit long – you know, maybe one minute or so – and Sandy became very impatient. She started getting behind the glass of the screen with her nails and breaking it," Kret said.

The team have now ordered a new, much sturdier screen of the type used at train stations. "So hopefully hooligan proof," Kret said. "I think we learned our lesson."