The causes of aging have been studied and debated about by various experts for centuries. There multiple views and ideas about the reasons of aging and the factors that make humans mortal. The genetic causes of death from aging today are multiple. Among them there are such factors as the loss of cells without restoration, nuclear mutations and epimutations, the damaged DNA, extra-cellular aggregates and cross-linkings and the decline of immune systems of human bodies.
Overcoming and even eliminating the causes of aging has been an attractive goal of many scientists, finding the key to aging would mean genetic immortality, yet in order to find this key all of the multiple causes of aging have to be removed and this complicates the process immensely and, basically, makes the goal unachievable. The contemporary perspective on aging views is as process programmed in the genome of humans and other living beings.
It is a well-known fact that the life spans of various creatures are very different in their length. For example, a butterfly’s life span lasts approximately twelve weeks, and the life span of a giant turtle estimates one hundred and eighty years or longer. The length of human life is in between of these two life spans, it may equal up to one hundred and twenty years (Whitbourne, 2002).
The theories supporting the point of view that the process of aging is programmed in the genome of humans were tested in the beginning of the 2000s through the application of various Human genome Projects that were designed to map the human genome and determine the complete sequence of human DNA. Learning all the genes of the human genome and discovering their sequence was the necessary procedure to grant the further study of human DNA and the process of aging.
One of earlier genetic theories states that there could be just one gene responsible for the aging of the body, but unfortunately this theory is highly improbable. Today, there also is telomere theory, which supposes that as the cells replicate, they lose a bit their sequences of the DNA on telomeres, this means that the telomeres gradually become shorter. Short telomere length over time starts to be sensed as the damage of DNA, and this is when the cells stop dividing. The telomere theory these days is considered one of the most reliable one among the programmed aging theories.
One more flow of theories is random error theories that are based on a belief that genetic error possibility increases in later life and causes aging. The theory proposes that waste that accumulates in our bodies prevents the cells from proper functioning. Finally, cross-linking theory is based on the fact that a molecule of collagen that is shaped as ladder and is responsible for a third of all the proteins contained in human body becomes altered in later life and this enforces aging.
Over the last decade the scientists identified over a dozens of genes that are responsible for the process of aging (Hekimi, 2000, p. 27). These genes also revealed the probability of the existence of more than one pathway that determine the human life span. This means that the process of aging occurs in interaction with various factors and is not determined to work strictly according to one scheme or program.
Reference List
Hekimi, S. 2000 The Molecular Genetics of Aging, Springer Science & Business Media, New York.
Whitbourne, S. K. 2002. The Aging Individual: Physical and Psychological Perspectives. Springer Publishing Company, New York.