﻿542 
  ANNUAL 
  EEPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1927 
  

  

  mark 
  the 
  less 
  improvement 
  do 
  we 
  find. 
  Tlie 
  century 
  seems 
  to 
  round 
  

   out 
  man's 
  age, 
  which 
  very, 
  very 
  seldom 
  runs 
  into 
  three 
  figures. 
  

  

  If 
  we 
  assume 
  this 
  100 
  years 
  as 
  the 
  limit, 
  we 
  must 
  substitute 
  for 
  

   Hart's 
  parabolic 
  law 
  of 
  progress 
  an 
  entirely 
  different 
  type 
  of 
  curve 
  

   the 
  specifications 
  for 
  which 
  may 
  be: 
  1. 
  That 
  we 
  start 
  off 
  at 
  the 
  

   present 
  average 
  duration 
  of 
  life 
  in 
  the 
  United 
  States, 
  58 
  years, 
  and 
  

   with 
  the 
  present 
  rate 
  of 
  life 
  lengthening, 
  41/2 
  years 
  per 
  decade; 
  2. 
  

   that 
  this 
  average 
  shall 
  approach 
  100 
  years 
  as 
  a 
  limit 
  ; 
  and 
  3. 
  that 
  its 
  

   rate 
  of 
  increase, 
  relatively 
  to 
  the 
  possible 
  room 
  for 
  improvement 
  still 
  

   left, 
  shall 
  be 
  maintained 
  at 
  10 
  per 
  cent, 
  or 
  about 
  the 
  present 
  rate. 
  

   The 
  figure 
  58 
  years 
  is 
  that 
  shown 
  by 
  Dublin 
  to 
  represent 
  the 
  average 
  

   in 
  the 
  registration 
  area 
  in 
  1921, 
  1922, 
  and 
  1923 
  in 
  the 
  bulletins 
  of 
  

   the 
  Metropolitan 
  Life 
  Insurance 
  Co. 
  (24). 
  The 
  results 
  of 
  such 
  a 
  

   forecast 
  are 
  : 
  

  

  Forecast 
  of 
  the 
  average 
  duration 
  of 
  life 
  

   Year: 
  ' 
  Year: 
  

  

  1922 
  58 
  1970 
  ,— 
  75 
  

  

  1930 
  61 
  1980 
  78 
  

  

  1940 
  : 
  65 
  1990 
  80 
  

  

  1950 
  69 
  2000 
  82 
  

  

  1960 
  72 
  

  

  By 
  the 
  year 
  2100 
  the 
  average 
  duration 
  of 
  life 
  would 
  be 
  94 
  years; 
  

   in 
  another 
  century 
  it 
  would 
  be 
  98 
  years; 
  in 
  another, 
  99 
  years; 
  and 
  

   thereafter 
  it 
  would 
  remain 
  between 
  99 
  and 
  100, 
  all 
  the 
  time 
  approach- 
  

   ing 
  closer 
  to 
  the 
  unattainable 
  limit, 
  100 
  years. 
  

  

  According 
  to 
  this 
  schedule 
  the 
  average 
  lifetime 
  would 
  reach 
  Dub- 
  

   lin's 
  estimated 
  increase 
  at 
  about 
  1940, 
  would 
  nearly 
  reach 
  our 
  com- 
  

   mittee's 
  quota 
  of 
  20 
  years 
  additional 
  within 
  the 
  50 
  years 
  specified, 
  

   and 
  by 
  the 
  year 
  2000 
  would 
  reach 
  the 
  highly 
  respectable 
  figure 
  of 
  

   82 
  years. 
  

  

  These 
  results 
  seem 
  conservative, 
  for 
  certainly 
  100 
  years 
  is 
  a 
  safe 
  

   figure 
  for 
  the 
  extreme 
  limit 
  of 
  life, 
  and 
  a 
  progress 
  every 
  decade 
  of 
  

   10 
  per 
  cent 
  of 
  the 
  room 
  for 
  improvement 
  left 
  seems, 
  on 
  the 
  basis 
  of 
  

   past 
  experience, 
  a 
  very 
  safe 
  figure. 
  We 
  ought 
  to 
  have 
  considerable 
  

   confidence 
  that 
  we 
  shall 
  actually 
  beat 
  this 
  schedule 
  and 
  become 
  

   a 
  Nation 
  of 
  octogenarians 
  by 
  the 
  end 
  of 
  this 
  century. 
  

  

  Before 
  considering 
  the 
  second 
  question 
  (whether 
  100 
  years 
  is 
  the 
  

   limit) 
  we 
  may 
  dwell 
  on 
  how 
  we 
  may 
  expect 
  at 
  least 
  to 
  keep 
  up 
  with 
  

   the 
  preceding 
  schedule. 
  

  

  We 
  can 
  do 
  this 
  partly 
  by 
  nature's 
  methods 
  of 
  acquiring 
  immunity, 
  

   as 
  the 
  negro 
  has 
  acquired 
  a 
  natural 
  resistance 
  to 
  hookworm, 
  and 
  

   partly 
  by 
  consciously 
  fighting 
  germs, 
  continuing 
  the 
  work 
  begun 
  by 
  

   Pasteur, 
  for 
  of 
  course 
  the 
  modern 
  quickening 
  of 
  life 
  extension 
  begins 
  

   with 
  him. 
  He 
  said 
  : 
  

  

  It 
  is 
  within 
  the 
  power 
  of 
  man 
  to 
  rid 
  himself 
  of 
  every 
  parasitic 
  disease. 
  

  

  