Slower growth rate linked to longer lifespan in Scottish study

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The slower you grow, the longer you live, a new study suggests.

Scientists looking at growth patterns in stickleback fish say they discovered lifespan is affected by the rate at which bodies expand early in life.

Bodies which grow quickly accumulate greater tissue damage, with life-shortening results.

A team from Glasgow University altered the growth rate of 240 fish by exposing them to brief cold or warm spells, putting them ahead or behind their normal growth schedule.

Researchers noticed the fish got back on track once their environmental temperature was returned to normal but the change in growth rate affected their rate of ageing.

The slow-growing fish lived for around 30% longer than the stickleback's two-year average, with a lifespan of nearly 1,000 days.

The lifespan of the fast-growing fish was 15% shorter than normal.

Professor Neil Metcalfe, from the university's Institute of Biodiversity, Animal Health and Comparative Medicine, said the "striking" results occurred despite all the fish reaching the same adult size.

"You might well expect a machine built in haste to fail quicker than one put together carefully and methodically, and our study suggests that this may be true for bodies too," he said.

"The results of the study are striking. It appears that bodies which grow quickly accumulate greater tissue damage than those that grow more slowly, and their lifespan is substantially reduced as a result.

"These findings are likely to apply to many other species, including humans, since the manner in which organs and tissues grow and age is similar across very different kinds of animal.

"It has already been documented in humans, for example, that rapid growth in early childhood is associated with a greater risk of developing ailments later in life such as cardiovascular disease in middle or old age, possibly because of the way in which the tissues of a fast-grown heart are laid down."

Earlier attempts to test links between growth rates and lifespan by altering diet proved inconclusive because the results could have been affected by the diet itself rather than its effect on growth.

The Glasgow team avoided the problem by keeping the fish on identical diets. All that changed were the temperatures to which they were exposed.

The paper, ‘Experimental demonstration of the growth rate - lifespan trade-off’, is published in the latest edition of the journal Proceedings of the Royal Society B.