Life clock ticking

Study suggests genetics can predict a species’ maximum lifespan.

Researchers from CSIRO and the University of Western Australia have figured out a way to tell how long a species’ life clock will keep ticking.

“Our method for estimating maximum natural lifespan is based on DNA,” says Ben Mayne, a postdoctoral fellow with CSIRO. “If a species’ genome sequence is known, we can estimate its lifespan.”

The “lifespan clock” screens 42 selected genes from short pieces of DNA in 252 vertebrate species. The density of these genes is correlated with lifespan to predict how long members of a given vertebrate species may live.

The authors suggest their findings – which are published in the journal Scientific Reports – may inform research into the ecology and evolution of living and extinct species, the protection of threatened species, and sustainable fishing.

When studying extinct animals, researchers used a species’ descendent as reference. The genome of the modern African elephant allowed lifespan estimations for the extinct woolly mammoth and straight-tusked elephant.

“Using our method, we found the maximum lifespan of the bowhead whale is 268 years – 57 years longer than people thought,” Mayne says.

“We discovered that extinct woolly mammoths lived for 60 years and the recently extinct Pinta Island giant tortoise from the Galápagos lived for 120 years.”

The Pinta Island giant tortoise genome is known from the last surviving member of the species, Lonesome George, who died at the Charles Darwin Research Station on Santa Cruz Island in 2012.

The researchers also studied humans and found our maximum natural lifespan to be 38 years. This matches lifespan estimates of early modern humans – before advances in medicine and lifestyle extended human life in many parts of the globe.

Using chimpanzees as reference, the study found that Neanderthals and Denisovans had a maximum lifespan of 37.8 years, similar to modern humans living around the same time.

Despite the successful outcome when studying vertebrates, the researchers were unable to accurately estimate the lifespans of invertebrates – possibly because many invertebrates do not exhibit the study’s chosen genes to the same extent as vertebrates.