Aging is a process we all start at birth and continue until death. Some people seem to age very gracefully, whereas others show signs of aging very early. Even ignoring the effects of infection or accident, quite a large range of life spans occurs among humans. Interestingly, there is a dramatic difference in the average life span of similar sized mammalian species. For example, mice live about 2-3 years, whereas other rodents of similar size average about 5‚Äď10 years. So age is a relative term with differences within and between species. Until recently, there was no clear molecular reason for aging other than slow accumulation of wear and tear on our cells, tissues, organs, and ultimately on our bodies as a whole. Until mammalian cells were cultured in the laboratory, understanding the molecular changes that occur over time was simply impossible. Many people try to offset the signs of aging, and spend vast amounts of money on products that claim to repair or mask the visible signs. Not surprisingly, the biotechnology industry hopes to tap into this flow of money by finding biological solutions to aging.