Contributions of the First World

     The  graph  above is  a  population  pyramid of the  United States of 
America for the year 2005; it displays the age and sex distribution of the 
population, in percent, from  which past and  future population growth can 
be  estimated.  Up  until  ages  35-39 years, there are  more  males  than 
females in each age class.  However, from the ages 40-44 up to 100+, there
are  more females than males. There are statistically more males born than 
females, however, females  are statistically more fit.  This may be due to 
the fact that females have two X chromosomes whereas  males only have one. 
If  males  inherit  a recessive trait on their  X chromosome,  it  will be 
expressed.  Since females have two X chromosomes, they will only carry the 
trait.                                                                     
     The population  distribution of The United States is  typical of that 
of first world countries.  In this particular graph, a small baby boom can 
be seen  around the 40-44 age class.  There is an even smaller baby boom - 
children  of  the  first  baby  boom - around  the 15-19  age  class.  The 
population  distribution  from  the age classes 00-04 to 35-39 are  fairly 
equal. This is indicative of a stable population size that will experience 
little to no growth in the future.  When looking at population pyramids of 
other first world countries (such as those of Canada, Australia, and  many 
Western European countries) the age structures  generally  suggest  either 
stable  populations  experiencing little to no growth, or negative growth, 
in which the size of the population is actually projected to shrink.