Theideathatlivingthingsshutdowninsteadofwearing
down has receivedsubstantial support in recent years.
Researchers working with the now famous worm C.
elegans (twice in one decade, Nobel Prizes went to
scientistsdoingworkonthelittlenematode)wereable,
by altering a single gene,to produceworms that live
morethantwiceaslongandagemoreslowly.Scientists
have since come up with single-gene alterations that
increase the life spans of fruit flies, mice, and yeast.
Thesefindingsnotwithstanding,thepreponderanceofthe
evidence is against the idea that our life spans are
programmed into us. Remember that for most of our
hundred-thousand-yearexistence—allbutthepastcouple
ofhundredyears—theaveragelifespanofhumanbeings
has been thirty years or less. (Research suggests that
subjects of the Roman Empire had an average life
expectancy of twenty-eight years.) The natural course
wastodiebeforeoldage.Indeed,formost ofhistory,
deathwasariskateveryageoflifeandhadnoobvious
connection with aging, at all. As Montaigne wrote,
observinglate-sixteenth-centurylife,“Todieofageisa
rare,singular,andextraordinarydeath,andsomuchless
naturalthanothers:itisthelastand extremestkindof
dying.”Sotoday,withouraveragelifespaninmuchof
the world climbing past eighty years, we are already
odditieslivingwellbeyondourappointedtime.Whenwe
studyagingwhatwearetryingto understandisnotso
much a natural process as an unnatural one.
It turns out that inheritance has surprisingly little
influenceonlongevity.JamesVaupel,oftheMaxPlanck
Institute for Demographic Research, in Rostock,