Crows

The crow’s name was Betty. And she was on her way to stardom. A gaggle of Oxford University scientists watched in wonder as she casually picked up a piece of wire in her cage and then used a nearby object to bend it at one end, transforming the wire into a hooked tool. That tool allowed Betty to hoist up a small container of meat – delicious pig’s heart – from inside a plastic tube. Lunch was served.

Back then, in 2002, Betty’s feat was a source of amazement. How did this crow solve such a complex problem so spontaneously? It suggested mental acrobatics akin to our own. This, the headlines read, was one stunningly clever crow.

Except that Betty was not quite as special as some first thought. Many years later, research showed that New Caledonian crows are habitual tool-benders. In the wild, they do it all the time. Observers had initially been startled by Betty’s behaviour because it looked as though she had come up with the design for her hooked tool on the fly. Like an engineer inventing a new machine.It was less a moment of genius – and more an expression of her nature.

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“I don’t want to downplay her cognitive abilities,” says Christian Rutz at the University of St Andrews. “At the very least, it forces us to reassess how insightful Betty’s behaviour was.”

New Caledonian crows belong to the corvid family of birds – as do jackdaws, rooks, jays, magpies and ravens. In recent years, the brains of these birds have been studied ever more closely. There is no doubt that some of them display impressive cognitive abilities. But intelligence is a murky subject. What exactly is it, in the first place? And why has it evolved?Intelligence is rooted in the brain. Clever primates – including humans – have a particular structure in their brains called the neocortex. It is thought that this helps to make advanced cognition possible. Corvids, notably, do not have this structure. They have instead evolved densely packed clusters of neurons that afford them similar mental prowess.

The specific kind of brain they have doesn’t really matter – corvids and primates share some of the same basic capabilities in terms of problem-solving and plasticity, or being able to adapt and change in the face of new information and experiences. This is an example of convergent evolution, where completely different evolutionary histories have led to the same feature or behaviour.

It’s easy for humans to see why the things corvids can do are useful. From identifying people who have previously posed a threat to them or others in their group to using gestures for communication – we too rely on abilities like these.

Rutz is unequivocal. Some birds, like the New Caledonian crows he studies – can do remarkable things. In a paper published earlier this year, he and his co-authors described how New Caledonians seek out a specific type of plant stem from which to make their hooked tools. Experiments showed that crows found the stems they desired even when they had been disguised with leaves from a different plant species. This suggested that the birds were selecting a kind of material for their tools that they knew was just right for the job. You wouldn’t use a spanner to hammer in a nail, would you?n the wild, New Caledonians use their tools to scoop insects out of holes, for example in tree trunks. Footage of this behaviour has been caught on camera.

You might think that some animals are smarter than others – with humans at the top of the proverbial tree. Certainly, humans do rely excessively on intelligence to get by. But that doesn’t mean we’re the best at every mental task. Chimps, notes Dakota McCoy at Harvard University, have been shown to possess better short-term memories than humans. This might help them to memorise where food is located in the forest canopy, for example.