Improved nutrition, clean water, better sanitation and huge leaps in medicine have been key in prolonging human life. The oldest known person — the Frenchwoman Jeanne Calment, who sold canvases to Vincent Van Gogh when she was a girl in the late 1800s — lived to the age of 122, dying in 1997. There is some debate about whether humans can naturally live much beyond that age, but it is hoped that science will take human lifespans beyond what is currently thought possible. Dr Andrew Steele, a British computational biologist and author of a new book on longevity, told MailOnline there is no biological reason humans can't reach the age of 200. He believes the big breakthrough will come in the form of drugs that remove 'zombie cells' in the body, which are thought to be one of the main culprits of tissue and organ decay as we age. Pills that flush these cells out of the body are already in human trials in and could be on the market in as little as 10 years, according to Dr Steele, who believes someone reading this could make it to 150 with the help of the drugs. Another field in particular that piques the interest of anti-ageing scientists is the study of DNA of reptiles and other cold-blooded animals. Michigan State University experts have begun studying dozens different types of long-living reptiles and amphibians — including crocodiles, salamanders and turtles that can live as long as 120 years. The team hope they will uncover 'traits' that can also be targeted in humans. ADVERTISEMENT Some experts think that eradicating the big killers — cancer, dementia and heart disease — could be the true key to longevity.