'Switching off' certain genes that contribute to the aging process could help increase lifespan dramatically, say American scientists after ten years of research.

Research conducted by the Buck Institute for Research of Ageing and the Unversity of Washington have managed to detect 238 genes which, when switched off, dramatically increase the life span of yeast cells.

Some of these genes are also present in mammals - and the scientists believe that one day, disabling them in humans could yield the same life-extending results.

Dr Brian Kennedy, lead author of the study and and CEO and President of the Buck Institute, said: "Almost half the genes we found that affect aging are conserved in mammals."

"In theory, any of these factors could be theraputic targets to extend healthspan. What we have to do now is figure out when ones are amenable to targeting."

The research, which has now been published in the journal Cell Metabolism, was slow and painstaking, and represented 10 years' work by a large team of scientists.

The groups of researchers from both institutions examed 4,698 yeast strains, deleting a single gene in each.

To find out which of these genes resulted in increased lifespan when deleted, the researchers counted the individual cells, tracking how many 'daughter' cells a 'mother' cell produced in its lifetime.

This detailed tracking revealed a wealth of information about how different genes affect aging - with some affecting how DNA responds to damage and keeps the body healthier for longer.

Although the studies were exhaustive, they are a small part of the wider goal of understanding the relationships between all the genes that affect ageing.