One area of research that holds great promise in extending the human life span lies in the area dealing with telomeres and telomerase.

We saw earlier that, for the most part, the cells of the body have the capacity to divide only a set number of times. Once they reach that limit - the Hayflick limit - and cannot divide further, they lapse into senescence and eventual death. As this happens with more and more cells in the tissues and organs of the body, these organs become increasingly impaired, and less capable of full function. When the failure becomes sufficiently widespread in organs crucial to our existence, we die.

We saw also that this Hayflick limit was tied directly to genetic structures called telomeres. Telomeres, we will recall, are the structures found at the ends of the chromosomes in the nucleus of the cell. The telomeres have been likened to the plastic tips found on the ends of shoelaces. Just as the shoelace tips protect the shoelaces, telomeres protect the chromosomes, particularly when they divide with the cell during cell division.

With each cell division, especially when we are getting on in years, the telomeres grow shorter and shorter. Once they have diminished to a certain critical length, the cell will divide no more.

Telomeres are regulated by an enzyme called telomerase, which is able to direct the telomeres to relengthen after each cell division. The ultimate regulator in this causal chain is the telomere gene, which is responsible for the production of telomerase.