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 femalesā urine causes them to . This is thought to be because āif you perceive youāve 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 theyāre not aroundā, says at the University of Otago in New Zealand.
The opposite is true for young female mice exposed to the smell of older malesā 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 ā including mice and ā Garratt and his colleagues wondered if young female mice that go through puberty later after sniffing older femalesā 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 infantsā 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 werenāt exposed to any adult bedding.
The newborn females exposed to the adult femalesā urine and soiled bedding went through puberty later and ended up living 45 days longer on average compared with the control mice ā an increase in lifespan of 8 per cent.
The reason why newborn females exposed to adult femalesā 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 malesā odours went through puberty earlier, as predicted, but they didnāt 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.
āIt isnāt necessarily surprising because we know that our environment shapes our health ā 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,ā says at the Monell Chemical Senses Center in Philadelphia, Pennsylvania.
Future research should try to determine exactly which odorants in older femalesā 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 āwe donāt have anywhere near the sense of smell that mice do or the same flexibility in our rates of developmentā, says Garratt.
Reference: bioRxiv, DOI:
