Edwin J. C. van Leeuwen et al / Animal Cognition

I read recently (Rhys Blakely, The Times, 9 July 2025) that Zambian chimpanzees have taken to placing blades of grass in their ears. This practice seems to have no practical purpose. It’s just a fashionable trend or fad.

Dr Jake Brooker of Durham University, co-author of a study published in the journal Behaviour, commented:

‘This isn’t about cracking nuts or fishing for termites. It’s more like chimpanzee fashion. It mirrors how human cultural fads spread: someone starts doing something, others copy it, and it becomes part of the group identity, even if it serves no clear purpose - and even if it’s sometimes uncomfortable.’

The chimpanzees with grass in their ears were observed in one tightly bonded group at the Chimfunshi Wildlife Orphanage. As juveniles they had been rescued from the illegal pet trade, and their time in captivity may account for their modish behaviour.

‘They don’t have to stay as alert or spend as much time searching for food. That may give them more cognitive room for play, experimentation and copying each other.’
Dr Edwin van Leeuwen, Utrecht University

The grass-in-the-ear trend is in fact a revival. It was first seen more than a decade ago among a separate group at the Chimfunshi refuge. The best fashions - like smocks, white socks and doing your top button up - always come back.

Chimpanzees have often been seen engaging in seemingly pointless activities – such as throwing rocks at trees, or creating collections of stones. In east Africa chimps have been recorded drumming with syncopated jazz beats (whereas in west Africa they prefer a 4/4 rock rhythm).

And it’s not just monkeys that are fond of fashion. Orcas living in the Pacific Northwest were recently observed wearing ‘salmon hats’: swimming around with dead fish on their heads.

Such eccentric behaviours may not have a functional survival benefit. But they could still have a purpose. Researchers have observed that they enable self-expression and strengthen social bonds. Shared rituals signal membership of the group.

Those of us working in the communication business should be mindful of this. Our strategies tend to assume that consumers are entirely sensible, practical, predictable.

The truth is we all do daft things. Our behaviour is often inconsistent, illogical, absurd.

‘It is human nature to think wisely and act in an absurd fashion.’
Anatole France

Sometimes we need to stop making sense.

'Pretty women out walking with gorillas down my street.
From my window I'm staring while my coffee goes cold.
Look over there (where?)
There, there's a lady that I used to know.
She's married now, or engaged, or something, so I am told.
Is she really going out with him?
Is she really gonna take him home tonight?
Is she really going out with him?
Because if my eyes don't deceive me
There's something going wrong around here.’

Joe Jackson, 'Is She Really Going Out With Him?'

No. 533