Humans might not be able to live forever, but they could one day reach an average age of almost 200, a new study has found. Such genetic alterations, called somatic mutations, are not inherited but occur naturally when cells split or become damaged over our lifetime, starting from the moment of conception. But those in the heart and the brain do not rejuvenate as easily, meaning they are much more vulnerable to damage through somatic mutations. “Ultimately, incorporating other major ageing factors could pave the way to a comprehensive theory of ageing,” the study says. “Any estimate of an upper limit to human lifespan based only on somatic mutations is highly speculative, as it considers only one candidate mechanism of ageing,” he said.