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The best explanation I found was on the book The Value of Tomorrow by Eduardo Giannetti, Brazilian philosopher and economist (in this chapter he had several con

The best explanation I found was on the book The Value of Tomorrow by Eduardo Giannetti, Brazilian philosopher and economist (in this chapter he had several consultants): If there is a trade-off between longer lifespan and reproductive capacity at a young age, there will also be a point of equilibrium. Suppose there was no senescence, we all lived perfectly healthy and at peak capacity for the duration of our lives. We would still have limited lifespan in nature, because of diseases, natural predators, etc. There would be a life expectancy, since people would not live forever. Now suppose a mutation occurs that grants the individual a boost in body functions at a young age with a caveat: a gradual decline in body functions after a certain age. If this certain age is way past the life expectancy of the population, this mutation would give competitive advantage to its bearers, with no real downside, since nobody lives way past the life expectancy anyway. This mutation would spread throughout the entire population and aging would establish itself in this population. The point of equilibrium in these trade-offs would be different for each population, since the environments and species are different, hence why hummingbirds, dogs, humans and turtles have wildly varying life expectancies. Trying to stop aging would involve stopping or mitigating these mechanisms, which are deeply ingrained in our systems. The consequences of doing so are far from straightforward, both to the individual (if we could not stop side effects to have the cake and eat it too) and to the population as a whole.

UhUhUhUh 12y ago
Yup. And the trade off between reproduction and aging is extremely well documented in biology. In short, reproduction prioritizes the set over the element. Kinda Borg-ish but that's what we have so far.
- mitteldorf 12y ago
  The tradeoff between reproduction and aging is sometimes present and sometimes absent. The successes are over-reported and the failures under-reported, so you might get the impression of "extremely well documented" with a cursory reading. Here is an example from Cynthia Kenyon's lab, "Healthy Animals with Extreme Longevity" http://www.sciencemag.org/content/302/5645/611.full http://www.sciencemag.org/content/302/5645/611.full
xaa 12y ago
This is the standard antagonistic pleiotropy hypothesis. While there are some examples of specific proteins and pathways that work this way (beneficial in early life, detrimental in late life), it is far from certain that this is the key driver of aging in evolution (for animals in general, as well as for humans specifically). For one thing, even in primitive human societies, the life expectancy is well into the 30s or higher (after you discount infant and early-life mortality). Yet aging starts rapidly deteriorating physical capabilities in the mid 20s. Secondly, one of the key definitions of aging is decreasing resilience with increasing age: so in reality, you cannot treat average lifespan as if it is a constant and the rate of aging is evolutionarily determined from that. Even in primitive man, which died of predation and infectious disease primarily, aging makes older humans much more susceptible to these things (physically weaker and weaker immune system). Finally, antagonistic pleiotropy does not explain why different organisms have very different maximum lifespans (in protected conditions), and some do not seem to appreciably age at all. Some more detailed criticisms: http://www.programmed-aging.org/theories/antagonistic_pleiotropy.html http://www.programmed-aging.org/theories/antagonistic_pleiot... Antagonstic pleiotropy probably plays some role, but it is a needlessly complex explanation when a simpler one exists: the body is a system, and over time, systems degrade and components are damaged. Its ability to repair this damage is considerable, but finite, since the repair mechanisms themselves can become damaged.
mitteldorf 12y ago
This way of thinking assumes that all life is evolved for maximum reproductive fitness. This is false. It is bedrock evolutionary biology, but it is also false. It turns out that the way evolution works is much more subtle than the postulates of R. A. Fisher's system, which dominated evolutionary thinking during the 20th century. Here is a good read on the subject: http://aeon.co/magazine/science/why-its-time-to-lay-the-selfish-gene-to-rest/ http://aeon.co/magazine/science/why-its-time-to-lay-the-self...

UhUhUhUh 12y ago

Yup. And the trade off between reproduction and aging is extremely well documented in biology. In short, reproduction prioritizes the set over the element. Kinda Borg-ish but that's what we have so far.

mitteldorf 12y ago
The tradeoff between reproduction and aging is sometimes present and sometimes absent. The successes are over-reported and the failures under-reported, so you might get the impression of "extremely well documented" with a cursory reading. Here is an example from Cynthia Kenyon's lab, "Healthy Animals with Extreme Longevity" http://www.sciencemag.org/content/302/5645/611.full http://www.sciencemag.org/content/302/5645/611.full

xaa 12y ago

This is the standard antagonistic pleiotropy hypothesis. While there are some examples of specific proteins and pathways that work this way (beneficial in early life, detrimental in late life), it is far from certain that this is the key driver of aging in evolution (for animals in general, as well as for humans specifically). For one thing, even in primitive human societies, the life expectancy is well into the 30s or higher (after you discount infant and early-life mortality). Yet aging starts rapidly deteriorating physical capabilities in the mid 20s. Secondly, one of the key definitions of aging is decreasing resilience with increasing age: so in reality, you cannot treat average lifespan as if it is a constant and the rate of aging is evolutionarily determined from that. Even in primitive man, which died of predation and infectious disease primarily, aging makes older humans much more susceptible to these things (physically weaker and weaker immune system). Finally, antagonistic pleiotropy does not explain why different organisms have very different maximum lifespans (in protected conditions), and some do not seem to appreciably age at all. Some more detailed criticisms: http://www.programmed-aging.org/theories/antagonistic_pleiotropy.html http://www.programmed-aging.org/theories/antagonistic_pleiot... Antagonstic pleiotropy probably plays some role, but it is a needlessly complex explanation when a simpler one exists: the body is a system, and over time, systems degrade and components are damaged. Its ability to repair this damage is considerable, but finite, since the repair mechanisms themselves can become damaged.

mitteldorf 12y ago

This way of thinking assumes that all life is evolved for maximum reproductive fitness. This is false. It is bedrock evolutionary biology, but it is also false. It turns out that the way evolution works is much more subtle than the postulates of R. A. Fisher's system, which dominated evolutionary thinking during the 20th century. Here is a good read on the subject: http://aeon.co/magazine/science/why-its-time-to-lay-the-selfish-gene-to-rest/ http://aeon.co/magazine/science/why-its-time-to-lay-the-self...