Animal intelligence: Startling new evidence emerges

Animal intelligence: Startling new evidence emerges
Published: 18 April 2007
Independent UK

All kinds of animals are proving to be brainier than we ever imagined. Clint Witchalls reports on the latest discoveries that put these species in a class of their own.

Orang-utans

BRAINPOWER:

We've known for some time that apes are brainy. Until a couple of years ago, there had been no observation of gorillas using tools in the wild. Then, in 2005, Thomas Breuer of the Wildlife Conservation Society, while observing lowland gorillas in the Republic of Congo, saw something remarkable. A female gorilla, named Leah, waded upright into a pond until waist deep, and then, unsure of herself, returned to the water's edge, grabbed a stick and proceeded to use it as a depth gauge.

Chimpanzees also fashion tools out of twigs, and in tests, one bonobo chimp named Kanzi used a computer to ask him: "Can you make the [toy] dog bite the [toy] snake?" Kanzi found the toys, put the snake in the dog's mouth and squeezed it shut - he understood that "dog" was the subject of the verb "bite" and that the direct object was "snake".

Dutch primatologist Carel van Schaik discovered orang-utans do something chimps don't - they use leaves as rain hats and make leak-proof roofs over their nests. The Harvard University psychologist James Lee recently argued that orang-utans are the most intelligent apes of all, knocking chimps off their pedestal - but these findings have yet to be verified.

Rats

BRAINPOWER:

An experiment just reported in the US found that rats are smart enough to know when they don't know something - an ability called metacognition. It was once thought that only humans had this ability, and later it was discovered that some apes have it too. In the recent study, lab rats had to decide whether a sound was short or long. A right answer led to a large food reward; a wrong answer to no reward. But if the rats declined the test, they got a small reward. When the sounds were clearly long or clearly short, discriminating was easy, but when the sounds were of a medium duration, the rats soon worked out that it was better to settle for the small reward, rather than risk an incorrect answer.

Scrub jays

BRAINPOWER:

Memory of episodes in your life is another ability once said to be uniquely human. If you have "episodic memory", you can go back in your mind to recall the event. This requires a concept of self - to have someone who appears in these memories. Dr Nicola Clayton, a professor of comparative cognition at the University of Cambridge, has demonstrated that scrub jays are capable of episodic memory. The birds are known for stashing food - and for nicking other scrub jays' stashes. If a jay buries a stash but spots that it's being watched, it comes back later to dig up the stash and move it - surely proof that the jay recalled the "episode" of being watched?

Now, Clayton has shown that scrub jays plan for the future too. Every morning, eight jays were let into either a compartment with no food or one with breakfast. They were then allowed to eat for the rest of the day. After a few days, the birds were given pine nuts to hoard. Anticipating a morning without breakfast, theyhid food in the "no breakfast" compartment rather than the "breakfast" one.

Dolphins

BRAINPOWER:

Dolphins at the Institute for Marine Mammal Studies in Mississippi are rewarded with fish for taking the litter out of their pool. One dolphin, Kelly, realised that when people dropped things in the water, she didn't have to hand over all the litter at once; she'd still get a reward even if she only handed over a shred of paper. So the dolphin hid the paper under a submerged rock and tore off bits to give to her keeper. One day, frustrated by the lack of litter, Kelly grabbed a seagull, handed it to her trainer and was rewarded with a fish. The next time Kelly was fed, she saved her last fish and later used it to lure gulls into the pool so she could catch them. She taught this behaviour to her calf, who passed on its knowledge to the other calves. Now all the dolphins are at it.

Dolphins have bigger brains than humans - whether taken as an absolute weight or as a ratio of brain to body size. And even if brain size isn't everything, they're clearly very intelligent.

Starlings

BRAINPOWER:

Noam Chomsky said that what makes human language unique is "recursive centre embedding". This means you can keep adding to the centre of sentences. For example, the words "the food was in the bowl" can absorb the phrase "the dog ate" to become "the food the dog ate was in the bowl". Timothy Gentner, of the University of California, trained starlings to distinguish between recursive centre embedded grammar and simple "finite state" grammar, working with complex patterns of warbles. Chomsky disputed this. "It has nothing remotely to do with language," he said, "probably just short-term memory."

Meerkats

BRAINPOWER:

Our ability to pass on knowledge through teaching is another factor that is said to separate us. But last year, scientists from the Cambridge University revealed that meerkats - those social creatures from the Kalahari - are master-educators. Their pups are initially unable to find their own prey and rely on food from other members of the group - meerkats often feed on dangerous prey, including scorpions.

The Cambridge researchers discovered that in order for the helpers to teach the pups how to handle food without putting them in harm's way, the older meerkats would kill or disable the prey before providing it to the pups. In the case of the scorpions, they often removed the sting.

The helpers would then modify the frequency with which they killed or disabled the prey according to the pups' age, gradually introducing pups to live prey.

Elephants

BRAINPOWER:

One test for self-awareness (long considered a uniquely human trait) is recognising yourself in a mirror. Bottlenose dolphins and great apes do it, and last year it was found that elephants do to. Researchers placed mirrors in the elephant enclosure at New York's Bronx Zoo. One elephant repeatedly touched an X painted on her forehead - a classic test. Elephants are highly social, and self-awareness and empathy are vital to living in their social groups.

Cichlid fish

BRAINPOWER:

Fish may not appear to have complex minds, but scientists at the universities of Leeds, Edinburgh and St Andrews have written a paper in the journal Fish and Fisheries claiming that fish are highly intelligent. "These days, fish are regarded as steeped in social intelligence, pursuing Machiavellian strategies of manipulation, punishment and reconciliation; exhibiting stable cultural traditions; and co-operating to inspect predators and catch food," says Dr Kevin Laland of St Andrews. Some build complex nests, others use tools. Cichlids, an African freshwater fish, are skilled actors; they play dead and when smaller fish approach to take a bite, they attack. Not bad for a primitive vertebrate.