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The Tree of Life

Except for certain bacteria that could be considered immortal, all other living beings
carry within themselves a precise genetic clock that limits the duration of their life.

In 1955, Hermann Joseph Muller, the American geneticist who discovered the way to cause artificial mutations in hereditary material, wrote in the prestigious journal Science : "Death supposes an advantage for life, in the sense that it provides the genes of it's descendants a greater opportunity to rehearse their merits, due to the fact that it clears the path for a newer start". Are we then genetically programmed to age?, What biological sense does life make?

Fortuitous alterations in DNA and some enzymes indispensable for the organism, the decline of the immune system, irreversible hormonal changes, the existence of a genetic program of senility that concludes with death and the activity of highly reactive and destructive molecules, are some of the hypothesis that researchers shuffle to explain cellular aging.

For some experts, the keys to senility lie in the history of life itself. Some hypothesis sustain that all of the process of control of life is lead by a battery of genes, gerontogenes, that where originally weren't responsible for destroying an organism. Maybe these genes of aging where capable of deceiving natural selection and persist if a species obtained some adaptive improvement in it's early age, and it's harmful effects weren't revealed until sexual maturity has been reached.

Thomas B.L. Kirkwood, from the Council of Medical Investigations in London, doesn't completely agree with this idea and upholds what he calls the theory of disposable soma. This theory states that living beings have intentionally neglected their energy in searching for systems that secure immortality, in exchange for mechanisms that guarantee the survival of reproductive cells and, as a result, perpetuity of the species.

This concludes my study of the topic of evolution and origin of life. Take a chance to visit the rest of my site.

1997 Eduardo Diaz Diaz

Last updated: May 14th, 1997