Newborn female mice that sniff odours from adult female mice live 8 per cent longer than expected, possibly because their puberty gets delayed.
We have known since the 1970s that getting young female mice to smell older females’ urine causes them to . This is thought to be because “if you perceive you’ve got lots of adult female competitors in your environment that could affect your ability to reproduce, it may pay to delay your sexual maturation until they’re not around”, says at the University of Otago in New Zealand.
The opposite is true for young female mice exposed to the smell of older males’ urine: they tend to , possibly because they sense an abundance of males to mate with and want to take advantage of that.
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Since going through puberty later is associated with dying later in many species – including mice and – Garratt and his colleagues wondered if young female mice that go through puberty later after sniffing older females’ urine also end up living longer.
To find out, they exposed newborn male and female mice to odours from adult mice over a 12-week period. They swabbed the infants’ noses with urine collected from adults and placed soiled bedding from the adults in their cages. As a comparison, another group of newborn mice were swabbed with water and weren’t exposed to any adult bedding.
The newborn females exposed to the adult females’ urine and soiled bedding went through puberty later and ended up living 45 days longer on average compared with the control mice – an increase in lifespan of 8 per cent.
The reason why newborn females exposed to adult females’ odours ended up living longer may be because their pace of development slowed down to delay their sexual maturation, which ultimately ended up stretching out their lives, says Garratt.
The newborn females exposed to adult males’ odours went through puberty earlier, as predicted, but they didn’t have shorter lives as a result. More research is required to understand why, says Garratt. There was no effect of any smells on newborn male mice.
Previous studies in invertebrates have found that lifespan can be altered by certain smells. For example, and .
The latest study appears to be the first to show that the lifespan of a mammal can be increased via their sense of smell alone.
“It isn’t necessarily surprising because we know that our environment shapes our health – for example, if you live in a very cold or hot climate, it may shorten your lifespan. It makes sense that odorants would be part of that,” says at the Monell Chemical Senses Center in Philadelphia, Pennsylvania.
Future research should try to determine exactly which odorants in older females’ urine or faeces drive the life-lengthening effect in young females, says Reisert.
It is unlikely that the same life-lengthening effect would occur in humans because “we don’t have anywhere near the sense of smell that mice do or the same flexibility in our rates of development”, says Garratt.
Reference: bioRxiv, DOI:
