﻿LENGTHENING 
  01*' 
  HUMAN 
  LIFE 
  FISHER 
  541 
  

  

  opened 
  ; 
  new 
  apparatus 
  and 
  new 
  technics 
  are 
  being 
  discovered 
  and 
  brought 
  Into 
  

   use; 
  an 
  increasing 
  number 
  of 
  trained 
  investigators 
  is 
  available, 
  and 
  unprece- 
  

   dented 
  funds 
  are 
  being 
  placed 
  at 
  the 
  service 
  of 
  scientists 
  in 
  this 
  field. 
  

  

  But, 
  plausible 
  as 
  this 
  all 
  sounds, 
  if 
  we 
  are 
  seeking 
  to 
  extend 
  the 
  

   figures 
  of 
  past 
  experience, 
  we 
  hesitate 
  to 
  follow 
  Doctor 
  Hart's 
  method. 
  

   He 
  virtually 
  assumes 
  that 
  the 
  curve 
  representing 
  the 
  average 
  dura- 
  

   tion 
  of 
  life 
  at 
  successive 
  future 
  dates 
  is 
  a 
  parabola 
  ascending 
  continu- 
  

   ally 
  and 
  with 
  increasing 
  speed 
  and 
  takes 
  no 
  account 
  of 
  any 
  possible 
  

   limit 
  to 
  human 
  life. 
  But 
  if 
  this 
  parabolic 
  law 
  really 
  holds, 
  why 
  

   stoj), 
  as 
  Hart 
  does, 
  at 
  the 
  year 
  2000? 
  At 
  that 
  time 
  the 
  rate 
  of 
  life 
  

   lengthening 
  would 
  be. 
  Doctor 
  Hart 
  finds,, 
  80 
  years 
  per 
  century. 
  Al- 
  

   lowing 
  for 
  the 
  same 
  acceleration 
  as 
  before, 
  within 
  another 
  century 
  

   the 
  average 
  lifetime 
  would 
  exceed 
  200 
  years, 
  and 
  in 
  a 
  few 
  more 
  cen- 
  

   turies 
  it 
  would 
  exceed 
  Methuselah's 
  alleged 
  record. 
  After 
  that 
  we 
  

   would 
  have 
  to 
  measure 
  human 
  life 
  in 
  thousands 
  of 
  years, 
  tens 
  of 
  

   thousands, 
  and 
  ultimately 
  in 
  millions 
  or 
  trillions 
  ! 
  Even 
  the 
  wildest 
  

   imagination 
  must 
  shrink 
  from 
  such 
  extravagant 
  hopes. 
  

  

  I 
  think 
  we 
  can 
  discuss 
  the 
  question 
  best 
  by 
  dividing 
  it 
  into 
  two 
  : 
  

  

  1. 
  If 
  there 
  exists 
  a 
  natural 
  limit 
  to 
  human 
  life 
  of, 
  say, 
  100 
  

   years, 
  how 
  far 
  may 
  we 
  expect 
  to 
  increase 
  the 
  duration 
  of 
  life 
  ? 
  

  

  2. 
  How 
  far, 
  if 
  at 
  all, 
  may 
  we 
  extend 
  the 
  alleged 
  natural 
  limit 
  

   of 
  100 
  years? 
  

  

  If, 
  as 
  has 
  commonly 
  been 
  supposed, 
  a 
  natural 
  life 
  cycle 
  exists 
  and 
  

   the 
  extreme 
  life 
  span 
  is 
  a 
  part 
  of 
  that 
  natural 
  life 
  cycle, 
  the 
  utmost 
  

   we 
  can 
  hope 
  to 
  accomplish 
  is. 
  to 
  eliminate 
  deaths 
  occurring 
  earlier 
  

   than 
  this 
  natural 
  limit, 
  which 
  deaths 
  for 
  the 
  most 
  part 
  may 
  be 
  called 
  

   premature. 
  This 
  is 
  merely 
  giving 
  eacli 
  individual 
  a 
  fair 
  chance 
  to 
  

   fill 
  out 
  his 
  natural 
  life 
  span 
  by 
  protecting 
  him 
  from 
  accidents, 
  dis- 
  

   ease 
  germsy 
  and 
  so 
  forth. 
  

  

  One 
  hundred 
  years 
  is, 
  for 
  the 
  sake 
  of 
  argument, 
  taken 
  as 
  this 
  

   alleged 
  natural 
  limit 
  because 
  it 
  is 
  conservative 
  and 
  because 
  it 
  is 
  the 
  

   limit 
  often 
  assumed 
  by 
  actuaries. 
  They 
  point 
  out 
  that 
  few 
  authentic 
  

   cases 
  are 
  Imown 
  in 
  which 
  this 
  supposed 
  limit 
  has 
  been 
  exceeded. 
  

   They 
  point 
  out 
  that 
  we 
  have 
  reduced 
  tiie 
  mortality 
  in 
  the 
  earlier 
  ages 
  

   but 
  not 
  in 
  the 
  later, 
  and 
  that 
  hitherto 
  the 
  chief 
  life 
  lengthening 
  has 
  

   been 
  of 
  infants' 
  lives. 
  We 
  have 
  changed 
  the 
  shape 
  of 
  the 
  survivor- 
  

   ship 
  curve 
  but 
  not 
  its 
  length 
  of 
  100 
  years. 
  

  

  In 
  England, 
  in 
  the 
  middle 
  of 
  the 
  last 
  century, 
  one-quarter 
  of 
  the 
  

   people 
  died 
  before 
  they 
  were 
  5 
  years 
  old. 
  In 
  the 
  beginning 
  of 
  this 
  

   century 
  one-quarter 
  died 
  shortl}^ 
  before 
  reaching 
  40. 
  Using 
  the 
  same 
  

   two 
  dates, 
  we 
  find 
  that 
  one-half 
  died 
  by 
  the 
  age 
  45 
  in 
  the 
  last 
  cen- 
  

   tury 
  and 
  by 
  65 
  in 
  this, 
  while 
  three-fourths 
  died 
  before 
  the 
  age 
  of 
  70 
  

   in 
  the 
  last 
  century 
  and 
  a 
  little 
  after 
  75 
  in 
  this. 
  Thus 
  the 
  advance 
  

   in 
  this 
  third 
  quarter 
  of 
  life 
  was 
  only 
  a 
  little 
  over 
  5 
  years 
  as 
  against 
  

   30 
  .or 
  35 
  years 
  in 
  the 
  first 
  quarter. 
  The 
  nearer 
  we 
  reach 
  the 
  century 
  

  

  