Are your telomeres telomering you something? Are we coming up short in the life span wars?
If primates are threatened then humans may be as well. My thesis is that plant life interdepends on animal species and insect pollination. If forests are devastated then plant and animal life will be drastically changed. Widespread desertification could follow, and concomittant changes in insect species and diversity. This could affect domestic crops, and cause widespread crop failures. In effect we are just one more primate species that could be extincted by plant-life failure on the planet.
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Humans gotta go too.
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Stindl argues that the protective caps on the end of chromosomes, called telomeres, provide the answer. Like plastic tips on the end of shoelaces, all eukaryotic species have telomeres on the end of their chromosomes to prevent instability. However, cells seem to struggle to copy telomeres properly when they divide, and very gradually the telomeres become shorter.
Stindl's idea is that there is also a tiny loss of telomere length between each generations, mirroring the individual ageing process.
Once a telomere becomes critically short it causes diseases related to chromosomal instability, or limited tissue regeneration, such as cancer and immunodeficiency. "The shortening of telomeres between generations means that eventually the telomeres become critically short for a particular species, causing outbreaks of disease and finally a population crash," says Stindl. "It could explain the disappearance of a seemingly successful species, like Neanderthal man, with no need for external factors such as
climate change."
Indicators for human extinction Human telomeres are already relatively short. Are we likely to become extinct soon?
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 (like those seen in the Aids patients or the elderly) 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 (the jury is still out on whether this is the case) may indicate severe telomere erosion, but other causes are possible. |
