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Will All Earth Species Eventually Die Out?

Will humans persist for many millions of years to come, or are we headed for an evolutionary makeover, or even extinction? According to a controversial new theory by Reinhard Stindl, of the Institute of Medical Biology in Vienna, it's suggested that all eukaryotic species (everything except bacteria and algae) have an evolutionary "clock" that ticks through generations, counting down to an eventual extinction date. And, the so-called protective caps on the end of chromosomes, called telomeres, play a large part. Like plastic tips on the end of shoelaces, all eukaryotic species have telomeres on the end of their chromosomes to prevent instability and very gradually the telomeres become shorter. Once a telomere becomes critically short it causes disease.

According to the theory, human telomeres are already relatively short, and the following indicators for human extinction are given:

  • Cancer--Cancer incidence does seem to have increased, but it is hard to say whether this is due to longer lifespans, more pollution, or telomere erosion. The shortest telomere in humans occurs on the short arm of chromosome 17; most human cancers are affected by the loss of a tumour suppressor gene on this chromosome.
  • Immunodeficiency--Symptoms of an impaired immune system are related to telomere erosion through immune cells being unable to regenerate. Young people starting to suffer more from diseases caused by an impaired immune system might be a result of telomere shortening between generations.
  • Heart attacks and strokes--Vascular disease could be caused by cells lining blood vessels being unable to replace themselves--a potential symptom of telomere erosion.
  • Sperm counts--Reduction in male sperm count may indicate severe telomere erosion, but other causes are possible.

Guardian Unlimited April 8, 2004

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