Study finds DNA predicts species’ maximum lifespan

Researchers have found a way to predict how long a species can live. For us homo sapiens, natural lifespan is surprisingly short.

A new genetic tool has revealed the lifespans of species such as the woolly mammoth Picture: istock

It has been at least 10,000 years since a human saw a mammoth die of natural causes on the Arctic tundra. But now we have a good idea how old such a mammoth would have been: 60.

Thanks to a new genetic tool we also know that not only would that have made the mammoth a fair bit older than most Homo sapiens lived to at the time, it would also have been older than our long extinct evolutionary cousins – the Neanderthals and Denisovans.

The finding comes after a project mapped the lifespan of hundreds of animals to their genetics. One of the markers, or possibly causes, of ageing is a process called DNA methylation, whereby chemical changes on DNA can “dial up” or “dial down” the action of specific genes. Research has suggested the density of sites for methylation, known as CpG sites, is related to ageing.

For a paper in the journal Scientific Reports, researchers took a database of more than 200 vertebrate genomes, all from animals who had known lifespans. They found that CpG density on 42 genes produced a lifespan “clock”, accurately predicting life expectancy on species not in the original sample.

The scientists, from the Commonwealth Scientific and Industrial Research Organisation in Australia, said that despite it being such a fundamental animal attribute there was a lot of uncertainty in maximum lifespans.

“It is frequently the highest reported value for captive animals because of the difficulty in estimating age for wild individuals,” they said. “Alternatively, it is an accepted consensus value for the majority of individuals within a species, or is based on records from a small number of wild individuals that have an age estimate as a result of exceptional circumstances.”

It is often difficult to estimate using related species. Some fish, for example, live for weeks but some for centuries. The new tool produces estimates across species and even extinct animals.

Because many mammoths died in permafrost their DNA is relatively well preserved. The scientists found that mammoths seemed to live for about five years less than elephants, which made it to 65.

For Neanderthals and Denisovans, who walked upright alongside Homo sapiens, the same method produced an estimated lifespan of 38. This was also the same for us. It is only since our days hunting mammoths that we have become the only species to defy its genetics and double its lifespan.

The Times