But that same year, a tortoise named Harriet died at the age of 176 in an Australian zoo. She was a celebrity, particularly because she had been a pet of Charles Darwin. Some less famous tortoises have been recorded actually living longer than Harriet. In both tortoises and clams, accumulating evidence suggests that the longevity could be due to genetic up-regulation of telomerase, an enzyme that helps keep chromosomes from wearing out by keeping nucleotide sequences called telomeres long.
Owen R. Fonorow, Follow #OWENRFONOROW at twitter