Lifespan clock finds our oldest animals
Tool to show which animals live longest can predict the ages of extinct species
Surviving for at least 200 years, the bowhead whale is the longest living mammal on Earth but zoologists have struggled to discover its specific life expectancy.
Now, a breakthrough genetic study has built the first “lifespan clock” which can predict how long an animal will live based on its DNA.
After analysing the genetic code of 252 vertebrates, Australian scientists found 42 genes which predict length of life. They were able to tell that the average bowhead will live for 268 years, about 57 years longer than the oldest known whale.
Long-living animals are notoriously difficult to track from birth to death, because researchers do not live long enough to follow them through their lives.
For some species, such as the Greenland shark which may live for more than 500 years, scientists use carbon dating, but the inaccuracy of the process means that estimates can be out by more than 100 years.
Some living bowhead whales have been discovered with harpoons in them dating from the 1880s, proving they can survive for huge periods but their true lifespan had remained a mystery.
Dr Benjamin Mayne, a molecular biologist at the Commonwealth Scientific and Industrial Research Organisation in Canberra, said:
“Bowhead whales are thought to be the longest living mammal, with one individual estimated as 211 years old.
“It is rarely possible to follow long-lived species from birth to death as they would normally outlive a generation of researchers. Using our lifespan estimator and the bowhead whale genome, we estimated the maximum longevity of the bowhead whale to be 268 years. This lifespan estimate is 57 years more than the oldest aged individual to date.”
The team also applied their lifespan clock to extinct species and discovered that the life expectancy of Neanderthals was 37.8. The woolly mammoth would have lived to 60 and the passenger pigeon, which died out in 1914, had a lifespan of 28 years.
They were able to reassess the lifespan of the pinta island tortoise, of which the last known male, Lonesome George, died aged 102 on the Galapagos islands in 2012.
“It estimated the maximum lifespan of the pinta island tortoise to be 120 years old. This lifespan estimation is 1020 years higher than most estimates of Lonesome George’s age at death,” said Dr Mayne.
The “lifespan clock” screens 42 selected genes for short pieces of DNA whose density is correlated with lifespan, to predict how long members of a given vertebrate species may live.
However, the researchers found it was impossible to create a clock for invertebrate species from their DNA, and they have not yet tested it on the Greenland shark, so its true age continues to remain elusive.The research was published in the journal Scientific Reports.
The oldest creatures
1. Greenland shark, 512 392 years
2. Ocean quahog clam 507 years
3. Bowhead whale, 211 years
4. Rougheye rockfish 205 years
5. Red sea urchin 200 years – The Daily Telegraph
Using our lifespan estimator and the bowhead whale genome, we estimated the maximum longevity of the bowhead whale to be 268 years