104 WHAT EVOLUTION IS 



from the fact that each individual or 

 pair of individuals gives rise to sev- 

 eral offspring and often to many. It 

 is not always appreciated what this 

 method of increase means. 



If a single plant produces at the 

 end of its life two seeds and these 

 grow to mature plants the next year 

 and produce each two seeds and so 

 on, in the twenty-first year the orig- 

 inal plant will be represented by over 

 a million descendants. Even an ani- 

 mal, such as the elephant which 

 breeds with extreme slowness, will 

 nevertheless in time populate the 

 globe, if all its progeny live and re- 

 produce. When rapidly reproducing 

 forms such as the insects are con- 

 sidered, the increase in numbers is 

 bound to be quickly prodigious so 

 that the swarms of locusts described 

 in the past seem as nothing to what 

 might have happened. All organisms 



