Science: Does your pet have an inner life?

Animal consciousness has been the subject of much ridicule, but some scientists now believe the process started 500 million years ago.

IF YOU keep a cat or a dog there are times when you'd swear it was almost human. It's pleased to see you, complains when you go, and if you notice it twitching and whining in its sleep you guess it's dreaming. It may not talk or be a whizz at mathematics, but it sees grass as green and inhabits a rich world of smells that you can't even begin to imagine.

Until quite recently that sort of account of a pet's inner life - similar to our own in some ways but dimmer in others - would have been greeted with a knowing sneer in scientific circles.

The whole idea that humans were conscious, let alone animals, was a delusion and foolish folklore. Ten years ago a standard psychology text book could declare: "Consciousness is a topic on which nothing interesting or worthwhile has been written."

Now that's all changing. In fact, claiming consciousness for your pets is modest. How about consciousness for a nematode worm or a primitive sort of sea urchin? That's how early at least one scientist suggested consciousness evolved, at a recent conference on the scientific study of consciousness in Tucson, Arizona.

Others suggested it might have first appeared with the first mammals. But even researchers who spent their day inserting needles into monkey's brains to find what cells fire when they see or touch, are beginning to admit that animals could be conscious.

"Defining consciousness is a real minefield," says philosopher David Chalmers, of the University of California at Santa Cruz, who was one of the organisers of the conference.

"At one level it's about having sensations, like the experience of seeing green or feeling hunger or pain. More sophisticated is the ability to be aware that you are experiencing something."

For those who believe that animals do have consciousness, the big problem is to explain what it is for. After all, we can now design robots that can learn to do very complicated things such as flying a jet plane without needing to be conscious.

"The point is that we do actually see things both consciously and unconsciously" says Dr Michael Goodale, of the University of Western Ontario in London, Canada.

That sounds odd, but Goodale has discovered that even something as apparently simple as seeing a glass and picking it up involves two visual systems, one conscious and one unconscious. "If you want to think of us in terms of robots and computers, we have a system that is like the controller back at base who gets an overall picture and makes decisions, and then another system that does the actual moving automatically."

Goodale uncovered his two systems by working with the sort of visual illusions that you sometimes see printed in newspapers - two circles that are actually the same size but because of the background one looks larger than the other. If you make a three-dimensional version of this, something interesting happens.

Ask people to judge which is the larger and they will be fooled, but ask them to reach out and pick up the discs one at a time and they will set their fingers the same distance apart for both.

"In evolutionary terms" says Goodale "it makes sense to have one automatic system that grasps, say, a branch correctly every time and another that links vision with memory and expectations. That conscious system gives you much more flexibility but also makes you prey to illusions."

So that gives us a good idea of the difference between conscious and unconscious seeing, and why a conscious one might be useful. Further evidence for the value of consciousness comes from Dr David Marks, of Middlesex University, London, who has been investigating the benefits of being able to create vivid mental pictures.

"You can discover if someone experiences strong images simply by asking them" he says. "But we've found that the self-confessed good imagers actually look at things differently. If you track their eye movements they are much more consistent when they see something for the second time than people who say they only have vague or fuzzy mental images. Lots of studies have now shown people who use vivid imagery are not only better at remembering detail, but are also more competent physically - top archers and basketball players are good visualisers. What's more, people who are clumsy and poorly co-ordinated are poor at visualising too."

Marks believes that this link between visualising and action isn't limited to humans.

"Monkeys can put together elements of a scene, like a banana and a stick, in a novel way to solve a problem. Rats, migrating birds and bees all seem to be able to build internal maps of their world for navigation. It seems reasonable to suppose that they all involve some form of conscious mental imagery."

Marks's research gives evolution something to work on. If you are going to say humans and animals have consciousness, then it has to be a property that is ultimately coded for by the genes. Otherwise it can't be selected for, and without selection it can't have evolved. So when might consciousness have first appeared?

The most controversial answer came from Stuart Hammeroff, of the University of Arizona. He has developed a theory that links consciousness with quantum processes in the brain.

"If you calculate how many brain cells you need to give you a conscious moment of around half a second, which is the rate that animals seem to function at, you get a figure of around 300 neurones." That's significant because the first time that animals with a primitive brain containing that many neurones appeared was about 500 million years ago.

"This was the time of what's known as the Cambrian explosion" continues Hammeroff. "For billions of years there had been little change in the simple life forms on the planet. Then suddenly there was an massive increase in the number and complexity of species. We don't know why, but one reason could be because they developed a primitive form of consciousness."

Even at this level, Hammeroff believes, a tiny flicker of consciousness would have been better than nothing. "When things operate at a quantum level you get more unpredictability and that could have given an advantage to one side or the other in predator/prey relationships."

The whole issue of consciousness is still too subjective for many researchers. But it's a topic where the personal is hard to avoid. Claimed one speaker: "Studies show there is a strong link between whether a philosopher believes animals are conscious, and whether or not he keeps a pet."

FROM THIS WEEK THE SCIENCE PAGE WILL APPEAR EVERY FRIDAY