Chimpanzees signal romantic interest by tearing leaves in front of a chosen partner, according to a leading scientist. Professor Cat Hobaiter, an expert in the evolution of communication at the University of St Andrews, described the behaviour as “basically chimp flirting” and likened it to a “pick-up line”.
Presenting her latest findings at the American Association for the Advancement of Science’s annual conference in Phoenix, Arizona, Professor Hobaiter said researchers have now identified 150 distinct ape gestures. Many resemble human movements, such as shooing motions or extending a palm to request something. The recently documented “leaf clipping” involves primates tearing or plucking leaves.
The study, published in the journal Scientific Reports, examined two neighbouring communities of East African chimpanzees in Uganda. One group preferred to rip individual leaves using the mouth, while the other employed a “leaf tear-pull” method, removing leaves one by one from a twig.
Professor Hobaiter explained that the technique is mostly used by males to attract females, though “it can go both ways”. The gesture may be performed loudly or discreetly, with some chimps carefully plucking leaves in silence. She compared it to plucking daisy petals, adding: “Maybe you don’t want to give the game away to the big guy around the corner that might out-compete you.”
Other gestures have taken years to decode. A chimpanzee spinning around is thought to mean “stop that”, while raising an arm signals “let’s travel”. Professor Hobaiter noted that apes share the same fundamental tools of communication as humans. However, she suggested that storytelling – a uniquely human trait – was the key difference, saying: “It was our need to form social connections and tell stories that pushed us into language.”
