In the second part of the study, the scientists tested fruit flies or Drosophila melanogaster that could not perceive odors well. The gene Or83b was mutated in these insects, leaving the flies with a severely reduced sense of smell, although they can smell some things.

These flies appear to be much longer-lived, said Libert. There was as much as a 57 percent lifespan extension. Most fruit flies live about 60 days. These lived longer than 80.

The researchers also found other differences in the flies who could not smell. The slightly obese female flies stored more triglycerides (which could then be used for energy). The flies that could not smell were also more stress-resistant.

If you expose them to 100 percent oxygen, which is toxic they survive very well, said Pletcher.

Pletcher, Libert and their colleagues do not know how applicable this finding is to higher-level organisms such as mice, primates and humans. For example, said Pletcher, a gene such as Or83b has not yet been described in mammals, which have hundreds of odor receptors, many of which have not been carefully studied.

They hope to figure out how exactly odors in general affect longevity in the fly and possibly extend that understanding to other organisms even humans.

Although a gene such as Or83b has not yet been described in mammals, Pletcher, Libert and their colleagues suggest that this finding may be applicable in higher-level organisms such as mice, primates and humans, all of which have hundreds of odor receptors, many of which have not been carefully studied.