WIRED: Professor Ramakrishnan, the crucial question in your book is why we die. Venki Ramakrishnan: By death, we mean the irreversible loss of the ability to function as a coherent individual. In this sense, it is therefore important to distinguish between cell death and death of the individual. Another curious finding was the fact that aging is not simply due to wear and tear on cells. Wear and tear happens constantly in all living things, yet different species have very different lifespans.