Humans might opt for eye contact or compliments when flirting, but chimpanzees show romantic interest by ripping up leaves in front of their crush, according to scientists. Professor Cat Hobaiter, an expert in the evolution of communication and social behaviour at the University of St Andrews, Scotland, has spent her career studying ape communication.

Presenting her latest findings at the American Association for the Advancement of Science's annual conference in Phoenix, Arizona, she said there are now 150 known ape gestures. Some bear a striking resemblance to human hand movements, including shooing motions and reaching out a palm to ask for something. One of the more recently discovered gestures is "leaf clipping", when primates tear or pluck leaves.

Prof Hobaiter explained: "This is basically chimp flirting. It's like a chimp pick-up line - you tear a little leaf at someone to show you like them."

Prof Hobaiter and her colleagues, who published their findings in the journal Scientific Reports, studied the practice in two neighbouring communities of East African chimpanzees in Uganda.

They found one community was more likely to use the "leaf-clip" technique, ripping apart individual leaves using the mouth, while the other preferred the "leaf tear-pull"method, which involved tearing or pulling leaves, one by one, from a twig.

Prof Hobaiter said the flirting technique was mostly used by males to attract females "but it can go both ways". It may also be performed loudly or more discreetly.

Describing how some chimps carefully pluck leaves from a branch, she added: "It's silent, like plucking daisy petals. Like a, 'She loves me, she loves me not,' pile of leaves.

"Maybe you don't want to give the game away to the big guy around the corner that might out-compete you."

Some gestures have taken years of analysis to decode. For example, a chimpanzee spinning around is likely saying "stop that", while raising an arm is thought to mean "let's travel".

*** Ensure our latest news headlines always appear at the top of your Google Search by making us a Preferred Source. Click here to activate or add us as Preferred Source in your Google search settings. ***

Prof Hobaiter said many different apes share the same basic tools of communication.

She added: "Fundamentally, there's no big missing piece in the puzzle that we have and they don't.

"And yet, we end up with this strange situation where we are writing poetry and sending people into space, and that's not what they do with their communication.

"We have the same tools, but something that linguists and evolutionary origin of language scientists have not thought about is a very characteristic use of human language, which is storytelling.

"Until that point, we did all the same things with all the same tools other apes were doing, and it was our need to form social connections and tell stories that pushed us into language."