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Name: jing
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993


Question:
Is there any hypothesis about senecense?



Replies:
YES, there are several. If you want the straight poop, read the review article in Nature volume 262, March 25 1993, pp. 305-311 by L. Partridge and N. H. Barton. I will tell you what little I know of this topic. There are two major types of hypotheses: adaptive and maladaptive. The maladaptive hypotheses basically state that ageing is the unavoidable consequence of living in a harsh environments amongst insults like radiation that can destroy your genes and cells. It is hard to believe that this is the whole picture as different life forms lives different amounts of time (thousands of years for some trees, and clonally reproducing fungi), but one can still save the hypothesis by claiming that certain organisms are better at protecting themselves from the environment. The other type of hypothesis is an "adaptive" one in that it claims that it is senescence is a better way to reproduce one's genes that by trying to live forever. It basically says that if you have one gene that helps the organism to reproduce early and die early, that gene will out reproduce one that reproduces late and dies late. Therefore it is beneficial (reproductively) to have genes that help you reproduce early and often, even if that means that they will have deleterious effects on your life later. Kind of stealing from peter to pay paul. A correlate of this is that organisms that reproduce only once tend to die soon thereafter, and those that reproduce many times seem to last longer. The answer to senescence could be a combination of these two hypotheses. Much of this work is theoretical and a satisfactory answer has not yet been obtained.

Jim Murray



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