Is there among other species a similar interest in experiences or activities 

 that are not essential to life? We do not know how the secondary sexual 

 characters originated, nor how important they are in maintaining life. But 

 human beings cannot avoid speculating and wondering and experimenting. 

 And perhaps we cannot help trying to use the ideas we get to support our 

 older beliefs or preferences. For example, many secondary characters are 

 clearly related to sexual reproduction in species that live far from the 

 original home of life in the ocean. But it does not follow that all secondary 

 differences between males and females contribute to this result or are other- 

 wise useful to the species. We know that in many species of moths the two 

 sexes have different wing patterns and colorings, which have nothing to do 

 with mating. These insects fly and mate only at night, anyhow, and their 

 movements are apparently directed by odor. One experimenter glued wings 

 of males on female bodies and vice versa, and discovered that the male finds 

 the female just as well. 



It is easy for us to "explain" what other living things do as if plants and 

 animals had feelings and tastes and purposes and enjoyments like our own. 

 Indeed, we sometimes give them credit for being more able and more clever 

 than we are ourselves. Perhaps the honeysuckle grew itself flowers in order 

 to attract insects so as to get them to carry pollen and so help it produce 

 seeds. Perhaps the male elk grew himself large horns in order to impress the 

 female of the species or in order to overcome rival males. Perhaps the nightin- 

 gale grew himself a song box, and the goat grew himself whiskers, in order to 

 attract the female. Perhaps. But would any of us claim that we grew our- 

 selves our own attractive or effective colorings, our hands and teeth and other 

 features, in order to ... ? We really don't know. 



Life is possible without the secondary sexual characters, as it is, indeed, 

 possible without sexual reproduction. Fine feathers and showy flowers are of 

 themselves without apparent "uses" in the economy of the individual organ- 

 ism. They consume energy and material, and they seem to contribute noth- 

 ing toward keeping the individual alive. 



In the course of time, however, modes of life seem to have become 

 more complex and to have involved more complex modes of reproduction. 

 All the elaborations in plants and animals, whether related to vegetation or to 

 reproduction, seem to have arisen only when there was a surplus of food and 

 energy. When a few algal or protozoan cells cling together after cell-division, 

 instead of drifting apart, there is already the possibility of some surplus. Where 

 several cells have teamed up, they can increase their total product through 

 division of labor; and their joint action makes it possible to produce "extras" 

 — which may or may not become "useful". 



We know that in the long run tools and machinery more than pay for 

 themselves in human organization. But we cannot design, not to say con- 



428 



