 Our chromosomes have centimeres and tetameres. Tetameres are on the end. Centimeres are in the center. And they unravel. And after about 120 years, that's about how long a human can live, they don't unravel anymore. The spring is up, in other words. But they have learned that there is a hormone that can repair the tetameres and centimeres to where they will unravel more. It sets the clock back. They learned that through cloning.