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How we can tell a person's age by their smell

Forget the Botox and hair dye -- people can smell your age, a study has shown.

In tests, volunteers were able to distinguish between young, middle aged and elderly individuals by sniffing their body odour.

But contrary to popular conception, "old person smell" was rated less intense and unpleasant than other age group odours.

Scientists collected armpit odour samples from three groups of donors aged 20 to 30, 45 to 55, and 75 to 95.

Donors were asked to sleep for five nights in T-shirts containing underarm pads which were cut up and placed in glass jars.

These were assessed by 41 "evaluators" aged 20 to 30 who were given pairs of glass jars in different combinations to sniff. On each occasion, they had to decide which jar contained samples from the older donor. Evaluators were able to discriminate between the three donor age categories, the researchers reported.

"Similar to other animals, humans can extract signals from body odours that allow us to identify biological age, avoid sick individuals, pick a suitable partner, and distinguish kin from non-kin," said lead researcher Dr Johan Lundstrom, from the Monell Chemical Senses Centre in Philadelphia, US.

"Elderly people have a discernible underarm odour that younger people consider to be fairly neutral and not very unpleasant.

"This was surprising given the popular conception of old age odour as disagreeable."