If only we could talk to the animals...

Wild Minds: what animals really think by Marc Hauser (Allen Lane, £18.99)

As a student, Marc Hauser funded monkey-watching by cleaning cages at a small American zoo. Half-way through the summer, he was propositioned by a female spider monkey. She approached him, cocked her head and slowly wrapped her arms round his neck. "She looked into my eyes and cooed several times," he recalls. When her mate sauntered over, she swatted the monkey on the head and he fled to the far side of the cage. Eventually, she loosened her embrace on Hauser, and he walked away.

As a student, Marc Hauser funded monkey-watching by cleaning cages at a small American zoo. Half-way through the summer, he was propositioned by a female spider monkey. She approached him, cocked her head and slowly wrapped her arms round his neck. "She looked into my eyes and cooed several times," he recalls. When her mate sauntered over, she swatted the monkey on the head and he fled to the far side of the cage. Eventually, she loosened her embrace on Hauser, and he walked away.

The brief encounter was never repeated, but what did it mean? Was the spider monkey sexually attracted to him? Might it have been a ploy to make her mate jealous? Could she be aware of any such feelings? It's tempting to speculate, but we should resist the urge, argues Hauser, a Harvard professor in psychology and neurosciences. He acknowledges that "it is difficult for us to do anything but interpret animal behaviour as we interpret our own" but claims that only experimental research can reveal what animals think and feel.

Anyone eager for stories of psychic pets, weeping elephants and altruistic dolphins will be disappointed with Hauser's carefully argued text. But his approach to animal minds has its advantages - and offers a popular entrée into scientists' minds.

Hauser doesn't doubt that many animals do have thoughts and emotions. But to understand anything about what animals think and feel we must look to their "mental toolkits". Some of the tools for thinking - a basic capacity to recognise objects, count and navigate - are well-nigh universal among insects, fish, reptiles, birds and mammals. But each species also has specialised toolkits - "mechanisms of the mind" thrown up by that animal's lifestyle. Crucially, such specialisations do not make one species "smarter" than another, and Hauser advises us to abandon our obsession with league tables of animal "intelligence". Evolution has ensured that each species is as "smart" as it has to be to survive.

If specialist mental toolkits don't make animals bright, they do "make each species wonderfully different from others". For millions of years, bats have been finding their way using echolocation, something that humans learnt to do just a few decades ago. In the early 1940s, when the US biologists Don Griffin and Robert Galambos announced their discovery of bat sonar, fellow scientists ridiculed the idea. "After all, how could mother nature pre-empt the navy, which had been working on the problem of sonar for years with nowhere near as much success as the bat?"

Hauser tells the story to highlight the dangers of human arrogance, but he is just as keen to lead us from the temptations of anthropomorphism. Chimpanzees can use sticks and stones to crack nuts, but is their take on the physical world anything like a hammer-wielding human's? Hauser recounts experiments that shed light on animals' knowledge of objects and the extent to which such knowledge guides their use of tools. He goes on to explore their counting and navigational skills, before diving into the deep waters of tactical deception, self-awareness and more.

Alas, the conclusions Hauser draws from all this science remain sparse. The pressing need for more research is a common refrain. Overall, Hauser errs on the side of caution, concluding that our closest primate relatives do not attribute to their fellows desires and intentions - something that your average human cannot help. He grants primates thoughts and emotions, but they are "jailed", imprisoned in organisms that lack the capacity for sophisticated language.

Most animals are like the character in Kafka's Metamorphosis, who woke up to find himself transformed into a beetle. "They are Kafka-creatures, organisms with rich thoughts and emotions but no system for translating what they think into something that they can express to others." But why would evolution generate inner experiences with no function in the real world? Like Hauser, I suspect further research might not be amiss.