Quails that invest more in offspring age faster and die younger, University of Exeter study finds
Scientists selectively bred Japanese quails into two groups of fowl – those laying either relatively large or small eggs
Last updated 15th Apr 2026
Birds that put more energy into parenthood age faster and die younger, new research shows.
Scientists selectively bred Japanese quails into two groups of fowl – those laying either relatively large or small eggs.
As the quails do not do much parenting after eggs hatch, the mothers’ main contribution is the resources they transfer to their eggs.
After five to six generations of selective breeding, females bred to lay larger eggs aged faster and died about 20% younger than females bred for small eggs.
The findings of the University of Exeter study support a fundamental evolutionary theory that high “investment” in offspring unavoidably leads to faster ageing and a shorter life.
“All living things have limited energy and resources, and face trade-offs between competing priorities,” said lead author Dr Barbara Tschirren, from the University of Exeter.
“Evolutionary theory suggests there’s an intrinsic link between ageing and reproductive effort – but this is quite difficult to test.
“Our study does just that. It shows there is substantial genetic variation in reproductive effort and ageing, that this genetic variation is linked, and that it can evolve quickly.”
The study, which was funded by the Swiss National Science Foundation, is the first to use an artificial selection approach in a vertebrate species to test this.
Dr Tschirren explained that the trade-off is whether to put energy into reproduction or “self-maintenance”.
For example, previous research has showed that quails selected for high egg investment have lower rates of cell repair and immune function.
In the final fifth or sixth generation of the quail study, large-egg-laying females lived 595 days on average, compared to 770 days for females bred to lay small eggs.
Males live much longer, so the study was too short to reach firm conclusions about the impact of selective breeding on male lifespan.
– The paper, Artificial selection for increased reproductive effort accelerates actuarial senescence and reduces lifespan in a precocial bird, is published in the journal Proceedings of the Royal Society B.