Research into the genetics of human longevity has focused on several different areas: genes that promote longevity, genes that prevent longevity, and genes that hasten aging.

Humans have found several genes that have an effect on longevity,⁹ but researchers have only identified two or three that are essential. Researchers at the University of California at Berkeley have identified some preliminary candidates for human longevity assurance genes. Certain genes in cell culture appear to permit those cultures to become immortal, that is, able to divide indefinitely without dying. This suggests they may play a role in enabling tissues and organs to maintain their function, though they may also put cells at risk of becoming cancerous.

Human longevity research has also looked at genes involved in the cell aging process, (how cells lose their ability to reproduce), as well as in apoptosis (the process by which cells are programmed to die). Both mechanisms, ironically, may play a role in increasing longevity. Cell death may be necessary, in part, to help clean out cells with genetic damage. If cells fail to die, cells with damaged genes can stick around and cause problems (think of garbage left out for a few weeks or years). This can hasten aging and the appearance of age-related disease. Researchers in Canada have identified genes that may serve as cell death-inducing genes. These may clear out damaged (and longevity-inhibiting) cells, and allow them to be replaced by healthy cells.¹⁰

In an attempt to understand normal human aging and perhaps develop anti-aging targets, some investigators are looking at diseases of accelerated aging. One of the most familiar and well studied of these diseases is Werner's syndrome.

Werner's syndrome is a disease of premature aging, and its symptoms don't begin until adolescence or later. Young people with Werner's syndrome develop gray, thin hair and wrinkles. They develop cataracts, diabetes, coronary artery disease, and unusual cancers. Researchers have linked Werner's syndrome to a specific gene. Scientists have found that mutations in that gene lead to abnormalities in DNA replication, which presumably leads to the aging that results.¹¹ Whether the abnormalities that lead to premature aging in Werner's syndrome are the same as those that lead to ordinary aging in seniors remains to be seen.¹²