It is but an evolutionary accident that we ended up as the planet of the apes, albeit slow, almost hairless apes with oversized brains. It is scary to think that we might have lived on the planet of the crows, with humans as mere intellectual curiosities of our avian masters — those big-brained, formidable looking crows.
Our feathered friends are arguably more successful than us mammals: there are 9,000 species of them, and just over 4,000 species of us; birds inhabit every continent and almost every type of environment — on land, in water and in the air. As for crows, there are about 120 species distributed over every non-polar continent from Africa to the Americas.
The idea that some birds are as intelligent as apes triggers mixed reactions. Many dismiss them as “bird-brained”, but others are disturbed by their alien intelligence, beady eyes and imposing beaks, as images of Hitchcock’s thriller pass alarmingly across the mind’s eye. A select few revere them — especially the crows and parrots — as clever, sometimes charming, and definitely devious tricksters, as anyone who has seen New Zealand parrots — keas — destroying windscreen wipers will testify.
Sometimes they are rather creative. Highly gregarious rooks use cigarette ends as an insect repellent to smoke out bugs from under their wings and, for their antics at the M4 Membury services, rooks won a BBC prize for being Britain’s cleverest animal. Approaching in pairs, they stand on opposite sides of rubbish bins and pull up the bin liner in tandem, carefully securing it with their feet until the food is within beak reach. Then they toss it over the edge where another rook waits to guard the stash from potential thieves.
As for that Aesop’s fable The Crow and the Pitcher, in which old mother crow used stones to raise the water level to quench her thirst, we now know this is fact, not fiction, thanks to the rooks.
Over the past 25 years there has been a revolution in our understanding of the mental lives of animals. Not surprisingly, this was originally the exclusive province of the primates, particularly the apes: it’s hard not to be seduced by their looking so much more like us than your average crow, and being our closest relatives. Ever since Jane Goodall’s classic studies on chimpanzees in the forests of Africa, it has been known that apes share aspects of our intelligence, such as using and making tools, and we now know they save them for later use, adding forethought as well as technological talents to their cognitive repertoire. These ideas were readily received: after all, it is almost 150 years since Darwin first argued that minds, like bodies, are shaped by natural selection, but it was assumed that intelligence evolved once — in humans and our closest ape ancestors.
There is increasing evidence, however, that some birds are just as smart as apes. Crows manufacture tools and show forethought, planning where to stash hidden food for tomorrow’s breakfast. Like apes, they are socially sophisticated and go to great lengths to outsmart the competition when it comes to finding and protecting food. That crows have intellectual capabilities on a par with apes not only suggests that the derogatory term “bird-brain” is obsolete, but also challenges assumptions about the uniqueness of our intelligence. Cognition must have arisen independently in apes and crows, for not all birds and mammals share their brainpower.
This finding raises three important questions. The first concerns brain size. How is a bird with a walnut-sized brain capable of such feats? One of the great mysteries of intelligence is why absolute brain size doesn’t matter. The blue whale has the largest brain of any animal but is certainly not the smartest, so size isn’t everything. For reasons we don’t understand what appears to be important is relative brain size: both crows and apes have much bigger brains than you would expect from the size of their bodies.
A second issue concerns the kinds of brain that support intelligence. A bird’s brain is differently structured to that of all mammals, bereft of the six-layered structure of our neocortex, which has long been thought to provide the unique machinery for intelligence. Avian brains have a nucleated structure, more like a fruitcake than a mammalian multilayered German chocolate cake.
And finally, how widespread is this intelligence? Is there an untapped source of other alien minds that we share our planet with? Next time you take a walk in the park or stop at Membury services, spare a thought for those feathered apes. Don’t leave your car window open: they may steal your food when you’re not looking, for these thieves aren’t thick.
Nicky Clayton, Professor of Comparative Cognition at the University of Cambridge.