Discussion of everything related to the Theory of Evolution.
Why do most organisms grow old and die, while some (e.g., hydra) are immortal? Is there an adaptive advantage to ageing?
One theory is "antagontistic pleiotropy," proposed by George C. Williams (who recently died at the age of 84). This theory holds that the genes that cause ageing also provide essential advantages, and thus they cannot be removed by selection.
But this remains an open question in evolutionary biology.
Both have been hypothesized. Some scientists think death is programmed for the benefit of offspring or others in the group. Some think the body is allowed to break down so that resources can be devoted to reproduction.
I would not be surprised if it was both. However, there are many organisms that have no problems in living hundreds or even thousands of years (certain trees, for example), so obviously environment alone is not able to make us living things die of old age. I have also heard of the theory that the genes that cause us to die of old age are genes that are beneficial during youth or early adulthood, and thus are sort of a trade-off.
Interestingly, there are some seabirds (don't recall the exact species, some kind of petrels?) that live much longer than other birds of their size, beause they have differently functioning telomerase or something. I'll post more on this if I happen to find my source again. Anyways, it seems that it is genetically possible to expand and organism's life span, but why humans haven't increased theirs over ~100 years remains a very interesting question.
It is probably possible. And if it's possible, people will probably do it. But what a wrenching social change if new generations are born but the old don't pass away.
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