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Anuraag Reddy

AIESEC India

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Why evolution could never solve aging?

Maybe aging is an essential mechanism to clear out the old and make way for the new like cells within a body?

Maybe every form of life is already close to the upper limit of life expectancy?

Maybe aging is in the nature of carbon based life and metabolism?

Maybe we genetically sacrifice our longevity to survive the stresses of competition.

Emerging Questions:
Is it that our metabolic processes are over-compensated for dominance in their sexual prime which prove detrimental for longevity?

Is it that genes leading to different lifespans are mixed indefinitely in nature that it was never possible to select for it?

Isn't an organism with a longer span of mating at an advantage?

My hypothesis:
In the absence of change in ones environment, or competitive stresses an organism would eventually adapt itself to survive longer.

If every organism is a product of evolution then there must of course be underlying mechanisms within itself to aid such an adaptive process.

Under the influence of adaptive pressure, it would encourage mutation or variations in order create successful variations and also increase the number of life-cycles and so reducing the lifespan.

Under the influence of competitive stress, the dominance would lead to reproductive success and not the span of mating during ones lifespan.

In the absence of change in ones environment leading to adaptive pressure, or competitive stresses from rivals to prove dominance. Species would evolve longer lifespans.

Just a Theory though! But it would predict that

Lifespans of living fossils which have undergone little change in time should be greater than their relatives which have recently evolved.

Life having evolved on geographically isolated places far from intense competitive pressures should have greater lifespans.

Living things higher up in the food-chain or with few natural enemies should have greater lifespans.

Life span in pair bonding species should be higher than tournament species.

Topics: aging evolution
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  • Nov 23 2011: It strikes me that extended aging is in fact a specific evolutionary DISADVANTAGE.

    On the one hand; It is clear that in animals that care for their young there is a specific advantage to parents surviving until their young are mature, and it there is even an arguement for survival well beyond procreative fecundity (as in humans where females typically survive not only long enough to rear their own young but even to assist in rearing their grandchildren).

    On the other hand; survival of an "unevolved form" of any animal over several reproductive cycles results in the potential for excess competition. While the "survival of the fittest" would favour the more evolved form any capability to learn would provide a potentially outweighting counter advantage to the less capable but "better informed" older generations.

    The consequence of this would be that the species as a whole would fail to evolve and ultimately have insufficient variation within it's population to address "shocks" and thereby be at risk of extermination.

    Following this thinking;
    Animals which don't care for their offspring would have life expectancies ranging from slightly longer than the time required to reproduce (such as the mayfly or the salmon) increasing to address potential risks associated with the development cycle (predictable life-cycle giving a short life while high risk of failure to develop gives longer life requirement)

    Animals which do care for their young would have a life expectancy of betwen say 2 and 4 rearing cycles (2 to allow their offspring to be fully reared up to say 4 to avoid excess competition with their own great grandchildren).

    The other expectation that this thinking would establish is that the more generations a particular animal "cares for" the longer its likely lifespan. (Humans, Elephants etc which care across generations tend to have multi-generational lifespans)
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      Nov 23 2011: I do agree that the affect of age on child-rearing is a significant advantage that proliferated through the population and developed species that adapted such an ability. This is a trait that is advantageous to unique species in unique situations.

      How would you explain the Galapagos turtle? I believe it is one of the longest living vertebrate yet abandons its eggs. It could also be that it is an isolated or rare occurence as well.

      A theory must be simple and able to explain everything but there can be few exceptions which should be explained by other superimposed factors. It must hold true for a majority of populations, measurable by controlling for other traits which affect the same characteristic.

      Is it possible that species started growing older long before they developed the behavior of grand-parenting? Uniquely Humans and Elephants are species which have barely any competition and adapt their environment and so have to face less adaptive pressures.

      Although there are other similarities as well, we have acquired learning so a longer learning period is definitely a benefit. But the greater apes have them too but have little impact on their environment and so have to face adaptive pressures. :)
      • Nov 24 2011: Anuragg, the case of the Galapagos tortoises face an extremely hisk of failure of breeding with young being very heavily predated with only about 1 in 1000 laid eggs survivng to maturity. Given an average clutch size of about ten eggs and four clutches per year it is easy to see how a simple replacement birthrate would require about 50 years of reproductive life so an average age of circa 70-75. The actual wild avaerge age of about 100 would yield an average of three adult offspring per female so provide for a slow population growth while resources permit. In this case the high level of predation requires that parent is extremely long lived.

        It is of course possible that species started to grow older independently of behaviour my point is that being long lived, while an advantage for an individual and potentially an adaptaion to allow for either long periods of dependency as in many "higher mammals" or high levels of predation in the young (sexually immature), once it has achieved that purpose it ceases to provide further evolutionary advantage (capacity for an organism to adapt to its environment such that its genetic inheritance can be preserved) and can indeed, in cases where learning is involved, provide a specific evolutionary disadvantage by alowing the unadapted ancestors generations out compete their potentially more appropriately adapted descendants.

        My expectation is that species which have extended their life-spans beyond the point where it is delivering evolutionary advantage (as opposed to individual advantage) will be more vulnerable to evolutionary shocks (environmental changes/novel predation/novel diseases etc.) and therefore more likely to fail to respond to those shocks.

        In the case of humans the pre-christian era book of psalms estimates the lifespan of the human as three score years and ten (70 years) the latest UN global estimates suggest the current human average life expectancy is 67.2 years (82 in Japan down to 40 in swaziland)

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