Chapter 8: Aging as the Fountain of Youth

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Chapter 8 Aging as the Fountain of Youth

• Nesse, Randolph M. M.D., and George C. Williams,
  Ph.D. Why We Get Sick The New Science of
  Darwinian Medicine. New York, NY Vintage
  Books, 1995.

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Main Points

• What is senescence?
• When does senescence begin?
• Natural Selection-Why does senescence exist?
• Proximate causes of senescence
• Female longevity

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What is senescence?

• Senescence is not a disease, but is the
  deterioration of all organ systems and every
  bodily capability
• Senescence begins shortly after puberty and
  continues until death

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How was senescence selected for?

• The genes that select for aging most likely give
  an advantage earlier on in life.
• It is more crucial in from an evolutionary
  standpoint that the individual live to
  reproductive maturity, than live to a healthy old
  age.

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Why is senescence still around?

• Until recently people on average did not live
  long enough to experience all of senescence
• Major effects of senescence do not take effect
  until after reproductive decline

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What proximately causes senescence?

• Free radicals are molecules that destroy any
  tissue they contact
• SOD neutralizes free radicals, is directly
  related to life span
• Uric acid eliminates harmful species of oxygen in
  body
• People sometimes experience gout as a side effect

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Life Span vs. Offspring

• Opossums that have lived without the presence of
  predators for thousands of years live longer than
  most and have fewer offspring

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Female Longevity

• Males on average die sooner than females
• Result of compromises that give a male a
  reproductive advantage over another male

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Summary

• Senescence effects everyone
• Deterioration of all systems
• Causes of senescence most likely give advantages
  at youth
• Various proximate causes have effect of senescence