All of the science and discoveries referenced in Extropy are based on actual events and actual research. The concept for this type of age defying medicine can be traced back to the early 1960s and scientist named Leonard Hayflick. Until this time, it was believed that if cells were taken from a human body and grown in a laboratory cell culture that they would continue to grow indefinitely. Therefore, it was believed the mechanisms that govern aging were not present at the cellular level.

Many still believe the simple "wear-and-tear" analogy of aging. For example, a person's body, like a car, will progressively break down as it is used over the years. But there are flaws with this theory. If a car's body gets scratched, it does not repaint itself but if a human's skin is cut, it will eventually heal. So the question remains: What controls aging and senescence?

Leonard Hayflick knew that this idea of immortal cell cultures must be wrong. In 1961 he discovered an error in the preexisting dogma and established that cells, even those cultivated in the lab, will divide only a set number of times (usually about 50 for humans) before they lapse into senescence, or cell death. The Hayflick Limit, as it was called, dictated that the number of cell divisions approaching 50 would coincide with the slow decline toward old age, and death would be imminent. This proved that aging took place at the cellular level.

So what causes this limited number of cell divisions and the eventual breakdown of the body? It was believed that the answer might lie in structures called telomeres.

DNA molecules control the production of proteins and enzymes that carry out all the functions of our body. But as we age, our DNA gets damaged and our cells stop functioning properly. We now know that there are cellular enzymes that repair DNA damage but in spite of these, something still causes cells to age.

On the end of each piece of DNA are structures called telomeres. These are long sections of DNA that don't code for any proteins but merely act as buffers that protect the important genes in the middle. The telomeres keep the genes stable and functioning properly. But these telomeres shorten each time the cell divides until they are gone, the DNA is no longer protected and the cell breaks down and dies.
If telomere shortening is responsible for cellular aging, then is there any way to stop them from shortening?

There is an enzyme called telomerase that actually rebuilds telomeres. But none of our normal body cells have this enzyme naturally and only two types of cells ever make telomerase. One type is germ cells. These are the cells that make sperm and eggs. Their DNA is passed down through every generation so it must not be damaged by age. Likewise, cancer cells grow out of control and do not die until the host dies. They have an abundance of telomerase and never cease to divide. Because of telomerase, cancer cells and germ cells are essentially "immortal."

Can telomerase and the study of telomeres be used to fight the aging process? This question is currently being explored but has not yet been fully answered in today's biotech arena.

Telomeres have been the focus of many prominent scientists' research over the last several decades. Dr. Elizabeth Blackburn Ph.D. heads the team of scientists at the University of California, San Francisco that has done extensive research to try to understand the role of telomerase in cancer and try to find ways to fight cancer by specifically targeting telomerase.

Dr. Michael West Ph.D. founded a company called Geron in the early 1990s to study telomeres and aging. While there, he led the team that first discovered the gene for telomerase and was the first to identify its entire gene sequence. West later left Geron and became the President of another company, Advanced Cell Technologies in Massachusetts where he is currently studying the potential of stem cells and cloning to fight disease and the negative effects of old age. West's book The Immortal Cell was a strong inspiration for many aspects of the story for Extropy.

Reversing Human Aging by Michael Fossel 1996, William Morrow

Dr. Michael Fossel M.D. and Ph.D. of neurobiology from Stanford University believes that telomere shortening times the onset and progression of aging and that telomere therapy will change the world. He published a book on the subject in 1996 called Reversing Human Aging.

Recommended Reading:
Merchants of Immortality by Stephen S. Hall 2003, Mariner	The Immortal Cell by Michael West 2003, Doubleday