Autism was previously thought to occur only in humans, but scientists say its appearance in another species will greatly increase our understanding of it in humans.

Autism is a neurological disorder that affects functioning of the brain, which can affect a sufferer's life to varying degrees.

It typically appears during the first three years of life.

The UK National Autistic Society (NAS) estimates that autism, which has many forms, affects more than 520,000 people in the UK.

The condition affects the normal development of the brain in areas of social interaction and communication skills.

People with autism typically have difficulties in verbal and non-verbal communication, social interactions and leisure or play activities.

Neurological abnormalities

According to the New Scientist, neurologists from the Pierre and Marie Curie University in Paris, Rouen University and New York Medical College bred long-haired albino guinea pigs that had the same brain abnormalities as those found in some autistic people.

The film Rain Man raised awareness of the condition

The defects occur in the cerebellum, the part of the brain responsible for co-ordination, and the guinea pigs that had them behaved in a manner typical of autistic patients.

The researchers placed altered guinea pigs - which they called GS - in cages with other non-altered guinea pigs and compared their social interaction.

They noted behaviour in areas such as sniffing, licking and attempts to mate.

In this environment, the GS guinea pigs were much less inclined to interact with their cage mates.

They also showed reluctance to explore or respond to their surroundings.

Public awareness

Paul Cann, chief executive of the NAS, said the research could prove important.

He said: "The NAS welcomes any developments which will further enhance knowledge of the causes of autism.

"Although not primarily a research organisation, we are always interested to hear of any initiatives which may help to improve the understanding of this complex developmental disability."

Autism was first identified in 1943, but popular awareness of the condition increased greatly with the release of Barry Levinson's Oscar-winning film Rain Man.

Dustin Hoffman won a best actor Academy Award for his portrayal of Raymond Babbit, an autistic man.

There is no cure for the condition, but various treatments can help alleviate the difficulties it causes.