What is the smartest species in the world? You might think it's humans by a long shot, but the reality is a lot more complicated.
Chimpanzees, for instance, can easily beat humans at recalling a set of numbers that was displayed for a fraction of a second.
Octopuses can learn to open pill bottles protected by childproof caps, which many humans can't figure out on their own.
Dogs and horses, among many species that spend time around humans, are able to recognize body language cues that are lost on us.
Many species can do stuff we can't even imagine: bats that map out space with echolocation; birds that figure out the complex mechanics of flight and landing; and ticks that identify passing mammals by the smell of butyric acid.
In fact, every species' operating system is finely tuned to do what it needs to do, which makes intelligence comparisons across species rather pointless.
"It seems highly unfair to ask if a squirrel can count to ten if counting is not really what a squirrel's life is about," de Waal writes. "The squirrel is very good at retrieving nuts, though, and some birds are absolute experts .... That we can't compete with squirrels and nutcrackers on this task — I even forget where I parked my car — is irrelevant, since our species does not need this kind of memory for survival the way forest animals braving a freezing winter do."
Dandy, a young male chimp described by de Waal, was smart enough not to reveal finding some buried grapefruits while in the company of larger males. Hours later he ran back unaccompanied to eat them alone.
Grande, another chimp, would sit quietly when unable to reach a banana hung from the ceiling, until in moments of inspiration she would spring up and try a new technique for reaching the banana: connecting sticks to create a longer tool or stacking boxes to climb higher.
Chimps show almost human levels of cognitive complexity in these actions. And again there are areas where chimp thinking surpasses human thinking — among them short-term recall and perhaps some kinds of social awareness.