SHYNESS MAY shorten a person's lifespan, findings from a new animal study suggest.

Two scientists from America found that rats with a fear of anything new were more likely to die early from cancer than less timid rats.

Animals identified as "neophobic" had a 60 per cent greater chance of dying. They also produced more stress hormones when in an "exploration arena" containing unfamiliar objects.

An almost identical hormone response is seen in children who are shy, inhibited and fearful. Such behaviour, which is characteristic of neophobia, is detectable as early as 14 months.

The scientists wrote in Proceedings of the National Academy of Sciences: "This finding provides strong support for using the natural variance found in ... rats as a model of fear-associated temperamental differences in humans."

Sonia Cavigelli and Martha McClintock, from the University of Chicago, studied 28 male laboratory rats which varied in their response to unfamiliar environments.

To discover whether the animals were neophobic or neophilic (non- fearful), the rats were placed in a tank and objects were placed inside. These included a bowl, a food dispenser, a tunnel, and a brick. The objects were replaced by new ones and the rats' behaviour monitored.

Neophobic rats moved around and inspected the objects only a little, whereas the bolder rats were more inquisitive and keen to explore.

The scientists found that the average lifespan for the neophobic rats was 599 days, compared with 701 days for the neophilic rats. Although the fearful rats died sooner, the cause of death was the same in all animals.

The scientists wrote: "Most strikingly, males identified as neophobic during infancy died earlier than males identified as neophilic during infancy. However, pathology at the end of life was similar between the two kinds of males."

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Last updated: 01/07/2004 - 02:37 PM