The Problem of Adaptation 21 



The phenomenon of old age (apart from its possible con- 

 nection with the cessation of the power of reproduction), 

 which leads to the death of the individual, has been looked 

 upon by a few writers as an adaptation of the individual for 

 the good of the species. It has been pointed out by these 

 writers that the longer an individual lives, the more likely it 

 is to become damaged, and if along with this its powers of 

 reproduction diminish, as compared with younger individuals, 

 then it stands in the way and takes food that might be used 

 by other, younger individuals, that are better able to carry on 

 the propagation of the race. It is assumed, therefore, that 

 the life of the individual has been shortened for the benefit 

 of the race. Whether such a thing is probable is a question 

 that will also be discussed later. We are chiefly concerned 

 here only in recording the different groups of phenomena 

 that have been regarded by biologists as adaptations. 



The so-called secondary sexual characters such as the 

 brighter colors of the males, ornaments of different kinds, 

 crests, color-pattern, tail feathers, etc., organs of offence and 

 of defence used in fighting members of the same species, 

 present a rather unique group of adaptations. These char- 

 acters are supposed to be of use to the individual in conquering 

 its rivals, or in attracting the females. They may be consid- 

 ered as useful to the individual in allowing it to propagate at 

 the expense of its rivals, but whether the race is thereby 

 benefited is a question that will be carefully considered later. 



The colors of flowers, that is supposed to attract insects, 

 have been already mentioned. The sweet fluid, or nectar, 

 secreted by many flowers is sought by insects, which on enter- 

 ing the flowers bring about cross-fertilization. Thus while 

 the nectar seems to be of no immediate service to the plant it- 

 self, it is useful to the species in bringing about the fertiliza- 

 tion of the flowers. The odors of flowers also serve to attract 

 insects, and their presence is one of the means by which in- 

 sects find the flowers. This also is of advantage to the race. 



