Sex sells, behavioural biologist Tom Roth knows. After all, he chose Tinder for orang-utans as the title of his dissertation. The walls of Roth’s office at the Utrecht Science Park are adorned with posters of various species of apes. ‘Some apes, like the orang-utan, are closely related to humans’, Roth explains. By studying apes, you can explain a lot in terms of evolutionary theories, for example.’
His PhD has a less fundamental premise, he explains. ‘I focused on the partner preferences of orang-utans. This is useful, because if you know what they’re attracted to, it’s easier to successfully pair them up. We usually put animals together based on compatible genetics, in the sense of: “These will produce healthy offspring together.” ‘But it’s just like with people: just because you’re genetically compatible doesn’t necessarily mean you like each other or find each other attractive.’
Contrary to what the title of his dissertation implies, the orang-utans didn’t actually swipe left and right, says Roth. ‘However, we did work with touchscreens. Through measurements, we were able to determine that female orang-utans spend more time looking at males with cheek pads (a trait that signals male maturity), but unlike humans, they can’t tell you why they do so.
ATTRACTIVE CHEEK PADS
‘To arrive at representative conclusions, we used a variety of measurement methods, from touchscreens where the orang-utans got to tap on differently shaped dots that they associated with different faces, to equipment that tracked eye movements in order to measure what types of faces they looked at for longer periods of time.’
Important to note is that orang-utans are ‘extremely sensitive’ to rewards, says the researcher. ‘Of course, they were given rewards after every experiment – they participated in everything voluntarily – but in the experiment with the touchscreens, this resulted in them mainly tapping the dot closest to them in order to receive their reward as quickly as possible. That’s why we considered the eye measurements to be more reliable.’
Roth found that orang-utans are mostly visually oriented: the apes were more likely to look at other orang-utans with attractive cheek pads. ‘Of course, these are just the results of the specific group of orang-utans that I’ve examined, but I can’t think of any reason why it would be different for other orang-utans.’
The dissertation also addresses the preferences of humans who, like their distant relatives, also have a preference for attractive faces. Roth describes how potential romantic partners pass through two “filters”, as it were. First and foremost, it’s the visual characteristics that matter, and only then do factors such as status, ambition and personality come into play. According to the PhD candidate, the dating industry could learn something from this.
Roth: ‘For example, an app like Tinder could stop using the swiping feature. The initial group of potential partners could also be filtered out based on eye-tracking in your phone, for instance. Only then should you reveal these people’s interests and personalities. Research shows that personality initially plays a relatively small role in partner choice, though it would obviously raise ethical questions if phones started measuring all of that information on you too.’
Roth does not just have feedback for dating apps. In an opinion piece in Trouw, the behavioural biologist expressed his annoyance with the reality show Married at first sight, in which singles are matched up and married to their true love ‘based on science’.
LOVE AT FIRST SIGHT
‘It is not at all possible to find an ideal partner “based on science”, especially if those people aren’t allowed to see each other beforehand. Love is far too unpredictable for that, especially in humans, who generally form long-term relationships.
But of course, attractiveness isn’t the holy grail either. When people find each other attractive, it doesn’t necessarily lead to love, but we do know that it’s an important precondition. It might mean that people are more likely to start dating, but that does not automatically guarantee long-term success. Just look at the orang-utans. A potentially attractive partner can completely ruin their chances in a new group by acting strangely. There’s so much more to it.’
Roth refutes the claim that this research has disproved the adage of ‘love at first sight’. ‘I most definitely do believe in love at first sight, but I don’t think we can predict it in advance.’
Tom Roth, Tinder for orang-utans: comparing sexually selective cognition among Bornean orang-utans (Pogno pygmaeus) and humans (Homo sapiens). PhD defence is 13 March