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Scientists have calculated the lifespans of extinct animals, including ancient humans, from the DNA they left behind.

Our extinct "cousins", the Neanderthals and Denisovans, reached the ripe old age of 38 years, less than half that of modern life expectancies.

Woolly mammoths, meanwhile, lived to about 60.

Australian researchers also analysed the DNA of living species, such as whales, for which few records exist.

The bowhead whale could be the longest-lived mammal, reaching more than 250 years of age, they said.

Until now lifespan has been difficult to define for many animals, especially long-lived ones.

"Knowing the lifespan of an extinct animal can provide insights into their ecology," said Benjamin Mayne of the Commonwealth Scientific and Industrial Research Organisation in Crawley, Australia.

"If a species is not reaching their natural maximum life span in the wild it may indicate environmental pressures pushing the species into extinction."

The scientists used DNA to estimate the lifespan of a species, looking at changes in stretches of DNA linked to ageing. These "DNA clocks" were used to predict a maximum lifespan for animals living and dead.

Calculating the lifespan of our close relatives gives clues to how modern medicine and changes in lifestyle have helped us live longer. In the past 200 years, the average life expectancy of humans has more than doubled.

The research can also tell us more about the ecology and evolution of living and extinct species, the protection of threatened species, and sustainable fishing, the scientists say.

The research is published in the journal .

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