Animals Do the Cleverest Things
The chimp who outwits humans; the dolphin who says it with seaweed; the existential dog
An elephant that never forgets its extended family, a chimp that can outperform humans in a sophisticated test of visual memory and an amorous male dolphin that likes to say it with flowers -- well, a clump of river weeds to be more precise. These are just some of the recent observations from the field of animal behaviour. They appear to show that there is no limit to the intelligence of animals, but what do we really know about the true cognitive powers of the non-human brain?
Experiments on wild elephants living in Kenya found that individuals can remember the whereabouts of at least 17 family members, and possibly even as many as 30. Tests in a laboratory in Japan found that chimps, and young chimps especially, have an incredible photographic memory. Finally, there was the story of the romantic river dolphins of Brazil. Males collected river weeds, sticks or even lumps of clay in their mouths to act as a form of sexual display to prospective mates. Scientists are convinced that it is not merely playful behaviour but a serious attempt at wooing the opposite sex with the cetacean equivalent of a Valentine's gift -- surely a sign of emotional intelligence.
The latest studies into the unusual behaviour of a range of species suggest that we should no longer assume that animals are just the dumb creatures that we've been led to believe since the days of St Thomas Aquinas, the 13th-century Italian monk whose moral philosophy formed the basis of our modern-day ethical treatment of animals. Indeed, scientists have found that animals are capable of all sorts of clever behaviour that we normally associate with human intelligence. They not only have good memories and a perception of the world around them, they also display feats of apparent far-sightedness and understanding that seem to go beyond the mental abilities of many people.
It used to be thought for instance that humans were the only tool-maker. Then it emerged that chimps in the wild have learnt to strip leaves off twigs, which they use to poke termite nests for food. Some years ago, scientists found that chimps, in fact, select a range of tools for different jobs, such as cracking nuts or carrying water. They were even found to pass on their knowledge to successive generations as a form of acquired, cultural inheritance.
Then last year, scientists revealed even more remarkable tool-making behaviour in chimps. They had video footage of chimps in the wild using a "tool kit" to dig for termites. A chimp would use a thick stick like a spade to dig a hole in the ground above a termite nest. It would then use a second, more delicate stick, which had been deliberately frayed at one end, to poke down through the open hole to search for termites, which would cling conveniently to the end of the frayed stick like peas on a dinner fork.
"These chimpanzees use something that doesn't happen anywhere else. They use a tool kit," explains Professor Andrew Whiten of St Andrew's University. "They use their hands and their foot to dig down, so they look like Mr McGregor with his spade digging down with great effort. We don't understand how possibly they could have worked out how to do that."
Even more remarkable tool-making was seen in the case of the New Caledonian crow. Oxford University scientists showed in 2002 that a particularly clever specimen of this species, called Betty, was able to fashion a hook out of a piece of straight wire and use it to "fish" for food concealed in a long tube. It was a bizarre demonstration of a basic understanding of cause and effect known as "folk physics". Even chimps have not shown such skills.
Another trait of intelligent life is being able to distinguish one creature from another but this has been taken to an extreme in the case of the biggest land animals. Elephants were already known to mourn their dead and to communicate with one another over long distances using barely audible, low-frequency growls. More recently, however, scientists have demonstrated that elephants in the Amboseli National Park in Kenya can distinguish between members of the two local tribes, the Maasai and the Kamba. A study found that the elephants became more nervous and wary when shown garments worn by the Maasai, whose young men sometimes spear the animals to prove their virility, but show no such behaviour in the presence of clothes worn by the Kamba.
"We expected that elephants might be able to distinguish among different human groups according to the level of risk that each presents to them, and we were not disappointed," says Professor Richard Byrne of St Andrews University, who led the study. "In fact, we think that this is the first time that it has been experimentally shown that any animal can categorise a single species of potential predator into subclasses based on such subtle cues."
But do these examples of unusually clever animal behaviour constitute intelligence? It depends of course on the definition of "intelligence". Most biologists and psychologists would agree that the human mind has an extraordinary intellectual ability, infinitely more sophisticated than anything seen in the natural world. We converse in a complex language, we think symbolically and creatively, we can plan for and anticipate the future and, perhaps most important of all, we can imagine what it must be like to be someone else.
Scientists call this latter attribute of human intelligence the "theory of mind" and it is one of the defining features of the human condition. It explains, for instance, why we enjoy watching plays and films -- we can imagine what the actors must be going through. We can also imaging someone's pain and pleasure, which is necessary for empathy. It is also at the routes of so-called Machiavellian intelligence, or the art of deception and manipulation. If we can imagine what another person is thinking about us, perhaps we can manipulate those thoughts to our advantage. But do animals show this level of intelligence. They can, and do, deceive one another, but is it because they have this theory of mind we know to be so human?
The theory of mind is best illustrated by a classic psychology test given to young children. Imagine two puppets called Sally and Ann who are given an apple to share. Sally puts the apple in a red box, watched by Ann. Sally then leaves the room and, in her absence, Ann switches the apple to a nearby blue box. When Sally comes back in the room, which box will she open to retrieve the apple?
Children over a certain age -- usually between four and five -- get the right answer. But younger children who have not yet acquired the theory of mind (and interestingly children with autism) say Sally will look in the blue box. They are incapable of seeing the world from Sally's perspective. They only see it from their own. To them, the apple is now in the blue box and that is where Sally will look.
This theory of mind is at the heart of much research into animal intelligence. Many experiments have been performed on chimps and dolphins, for instance, to see if they are capable to seeing the world from another's point of view. The theory of mind is one of the most important attributes of intelligent behaviour and scientists are keen to know whether it exists elsewhere in the animal kingdom.
"There have been a number of studies on animals showing absolute compatibility with the theory of mind but none of them have excluded the possibility of other explanations," says Alex Kacelnik, professor of animal behaviour at Oxford University, who carried out the study on Betty the New Caledonian crow. The difficulty with testing the theory of mind on dumb creatures is that you cannot ask animals what they are thinking.
Perhaps one of the best studies yet into theory of mind was carried out on captive orang-utans by Professor Byrne and his colleagues at St Andrews University. These apes were accustomed to begging for food from their zookeepers so Professor Byrne decided to try to exploit this behaviour to test whether the apes could imagine themselves inside the minds of their human keepers.
The keepers were asked to place two items of food outside the cage of the orang-utans, but just out of their reach. One item was a tasty banana, the other something not quite so tasty, such as a leek. Not surprisingly, the apes made lots of begging gestures towards the banana. The scientists reasoned that if the orang-utan was capable of theory of mind then the ape should respond differently according to whether the keeper gave them the banana or the leek.
If the keeper responded to the begging pleas by giving the orang utan the leek, then the ape might vary its behaviour realising that the keeper does not realise that it is the banana it wants, not the leek. This is exactly what the scientists found. It was also reasoned that if the keeper gave the orang-utan half the banana then the ape would continue with the same style of begging behaviour that had earned it half the reward. Again, this is exactly what happened.
So has the orang-utan been shown to have a theory of mind? Not quite. It is true that one explanation for the findings is that the orang-utan was able to judge whether its gesturing to the keeper was having the desired effect because the ape was capable of a theory of mind. However, there are also other possible explanations, admits Professor Byrne. A more mundane suggestion, for instance, is that the orang-utans were simply exasperated with not getting a banana, and so employed a different set of begging gestures.
Both Kacelnik and Byrne say that it is unhelpful to talk about animal intelligence in the context of comparisons between species, and especially with human intelligence. So often we tend to compare what an animal can do with other animals, or with people, which is unfair and artificial, they say. "It makes no sense to say that a fly is smarter than a pig just because it can fly," says Kacelnik.
The point they both make is that animals are exquisitely adapted in their behaviour to survive in their particular habitats. If that means displaying a form of behaviour that we perceive to be intelligent, then we are guilty of anthropomorphism. The New Caledonian crow, for instance, is a comparative genius when it comes to making tools in a laboratory. But this is because food is scarce in its wild habitat on the Pacific island of New Caledonia, and the most nutritious beetle grubs it needs to survive are difficult to get to without the help of a simple tool made from twigs, grass or leaves.
Betty the crow showed that she was clever at making a hook-shaped tool from straight wire to fish for food. But she shared her cage with an older, and perhaps wiser, male bird called Abel, who took no interest in making tools. He simply waited for Betty to fish out the food from the tube before bullying her into giving him a piece. So who was the most intelligent?
Homing pigeons owe their name to the ability to return home from distant, unfamiliar release points -- in some cases, even if they've been transported, anaesthetised and deprived of all information about the journey. They were used to carry messages in both ancient Greece and China, and by the 16th century were being used in formal postal services. In 1860, Paul Reuter employed a fleet of 45 to deliver news and stock prices between Brussels and Aachen. Only in 2002 did India's police force retire its pigeon messenger service, when it was made redundant by e-mail. Homing pigeons have proved especially useful during times of war. One bird, "Cher Ami", was awarded the French Croix de Guerre for his heroic service during the First World War in delivering 12 important messages, despite sustaining a bullet wound. Equally amazing, but for different reasons, is the unfortunate bird that set off from Pembrokeshire in June 1953. It returned, dead, in a box postmarked "Brazil", 11 years later.
Viewers of Flipper do not need to be told that dolphins are cleverer than most inhabitants of the sea. Whether he was upholding the law, or embarking on a daring sea rescue, the iconic TV hero's brainpower never failed to amaze. Even without television trickery, dolphins are smart. The latest evidence of intelligence came this week, when researchers published the results of a study in the Brazilian Amazon which showed male members of pods carrying "gifts" in the form of sticks, or, most endearingly, makeshift bouquets made from seaweed, to attract mates. DNA tests revealed that the males who carried the most gifts proved the most successful fathers. Research in Australia showed bottlenose dolphins use bits of marine sponge to protect their noses while they probe the seabed. Scientists say the behaviour is evidence that they show signs of culture learned from their forebears, rather than passed down in genes.
While they may not yet have developed the power of speech, as exhibited in the upcoming Jerry Seinfeld film, Bee Movie, and are all too easily snared by beer traps in summer, bees are unexpectedly clever insects. As early as 330BC, Aristotle described the remarkable "waggle dance" bees use to communicate with members of the hive. It was originally thought the dance was designed simply to attract attention, but in 1947, Karl von Frisch, who was later awarded a Nobel Prize for his work, deduced that the apparently random runs and turns of the dance, which bees perform in groups, correlates directly to the position of the sun in relation to the location of food. If a bee runs from the six to 12 o'clock positions, it means food is in the direction of the sun. The number of waggles dictates how far away the food lies.
Most dog owners will claim their pooch is the smartest in the park. But retrieving sticks or barking at postmen, while impressive when compared with the skills of, say, a jellyfish, is hardly rocket science. However, new research suggests mutts are capable of much more: in an experiment at the University of Vienna, two border collies, an Australian shepherd and a mongrel were presented with images on a touch screen. The pairs of photos offered the choice of a landscape or a dog. When the dogs used their nose to push against the dog image, they got a treat. If they plumped for the landscape, they were forced to wait a few seconds before the next round. The training stage complete, the dogs were shown landscape and dog photos, and continued to correctly pick out the dogs. In the final phase, the dogs were shown an unfamiliar dog superimposed on a landscape they had seen in training. Even then, the animals were able to pick out the dog. Scientists say the results show that dogs can use abstract concept, a skill which had been attributed only to birds and primates.
The 65 million-year-old leatherback turtle has witnessed the fall of the dinosaurs and the rise of humanity. But the giant sea creature is most extraordinary for its ability to travel huge distances, from the cold waters in which it feeds to the tropical and subtropical beaches where it hatches its eggs. Female turtles originally tagged in French Guiana off the coast of South America have been recaptured on the other side of the ocean in Morocco and Spain. In 2006, the so-called "Dingle turtle" made headlines after being tagged off the west coast of Ireland and embarking on an astonishing 5,000-mile journey to the Cape Verde islands, off West Africa. Leatherbacks are found from Alaska to New Zealand.
Everyone knows man's closest living relative is the sharpest tool in the animal box. After all, what other animal can brew up a cup of PG Tips while wearing a bowler hat? This week, however, the publication Current Biology has shed new light on the brain power of chimpanzees, revealing them to have photographic memories far superior to our own. Until now, it was not thought chimps could match humans in mental tests. But researchers in Kyoto discovered that chimps could recall a sequence of numbers displayed to them (for a fraction of a second), outperforming students who took the same test. The research suggests that short-term memory may have been more important to earlier humans, possibly because of our modern reliance on language-based memory skills.
Whale song, which is associated in particular with the humpback, is something of a mystery to scientists. Male humpbacks sing mainly during the mating season, but it is not known whether the song is used to attract females or to ward off other males. The song itself is complex. At any one moment, all the males in a population sing the same song. Over time the song slowly evolves into something new, with all the whales making exactly the same changes to their pattern of singing. Studies suggest that, once a population of whales has moved on from a particular pattern, it will never again return. Other whales such as the sperm and beluga also make songs but none are as complex as that of the humpback.
The old adage that elephants never forget was proved to have a basis in scientific fact in 2001, when research showed that matriarchs, who lead the herd, have an uncanny ability to remember faces. This enables them to know when alert their brood to menacing interlopers. Now, scientists at the University of St Andrews have shown that pachyderms are even smarter than that: a study of 36 family groups in Kenya suggests that elephants can build a mental map of where herd members are by combining their memory with a keen sense of smell. Researchers lay urine samples from wild elephants in the path of a herd. When the leader encountered the scent, it reacted with surprise because its memory told it the animal was walking behind, and could not have been able to lay its scent ahead.
The Arctic tern
Even more prone to wander than the leatherback turtle, the Arctic tern takes the longest regular migration of any known animal, from its Arctic breeding grounds to the Antarctic and back again every year. On this journey of about 22,000 miles, the seabird enjoys two summers and more daylight than any other creature on the planet. One chick demonstrated its flying ability by setting out from Labrador, Canada, in July 1928 to arrive in South Africa four months later. Another unfledged chick tagged on the Farne Islands, off the coast of Northumberland, in 1982 flew 14,000 miles to Melbourne, Australia, in just three months. Over its life, the Arctic tern will travel about 500,000 miles.
They might be famous for their brawn -- ants can carry up to 20 times their body weight, the equivalent of a woman strapping a hippo to her back -- but ants are not renowned for brains. When it comes to delegation, however, they're smart. Males cannot claim much credit for this -- they spend their days wandering around accepting food until they mate, when they promptly die -- but worker ants, who are generally sterile females, are clever. They perform tasks such as foraging, defending, preparing food, construction and attending to the queen. The most dangerous task is foraging, so older, more expendable ants are given the job, while the younger ones wait on the queen.
New Caledonian Crows
The ability to fashion tools has always been held as uniquely primate, distinguishing us from (apparently) less intelligent creatures. But humans and apes are not alone in having tool-making skills. Crows amazed the science community in October when footage -- recorded using tiny "crow-cams" on the tails of New Caledonian crows -- showed the birds creating advanced implements. One crow was observed whittling twigs and leaves with its beak to fashion grabbers designed to retrieve grubs from the ground. The New Caledonian crows are the only known non-primate to create and use new tools.
Chimps might be able to outwit Japanese university students in a test of photographic memory, and are traditionally considered to be second only to humans in the intelligence stakes, but research published earlier this year suggested that orang-utans were the smartest swingers in the ape world. Scientists from Harvard University studied orang-utans in Borneo and found them capable of tasks that chimps could only dream of, such as using leaves to make waterproof hats and roofs. They also gathered evidence that the orange-haired apes have developed a culture in which adults teach the young how to make tools. Viewers of David Attenborough's documentaries will remember the astonishing film of an orang-utan climbing into a canoe and using a paddle.
Additional reporting Simon Usborne and Richard Molloy