We are all used to feeling younger than our years and occasionally older than our birth date would suggest. In effect, we have two ages-chronological and biological. Chronological age simply states the number of years that we have been alive, whereas biological age is a measure of how well our bodies are performing, in relation to the rest of the population. So how is it determined? LLAMA host Peter Bowes delved into the science with Elysium Health, which has developed Index, a DNA test that tracks how fast we have been aging, based on our epigenome, which regulates the way genes work. In this episode, Peter meets Dr. Morgan Levine, an assistant professor of pathology at Yale School of Medicine and an advisor to Elysium Health. They discuss the background to Index, its use of epigenetic clocks to put a number to our biological age, as well as the test's accuracy and implications for healthy living.