Sexual and Arttfiical Selection. 119 



inch crack. A pampered Berkshire or China pig would stand no show 

 in an unaided competition with these "razor backs." Natural selection 

 must invariably encourage and increase those characteristics and pecu- 

 liarities that are of advantage to the individual in preserving it and per- 

 petuating its breed. When a hog is under human domestication, the 

 points tending to its preservation are perfect digestion and assimilation, 

 an ability to get fat quickly, and a form upon which the flesh can be 

 packed with the greatest economy of room, and which is least adapted 

 for those activities which convert food into motion instead of flesh. In 

 short, very different qualities are required to preserve the hog while in 

 domestication from those which best preserve him while in the wild 

 state, but the principle of the selection is the same in each case; and 

 those animals having points which best adapt them to live, all the con- 

 ditions of their environment considered, are the ones most likely to sur- 

 vive as a race, and transmit their qualities to a posterity. Artificial 

 selection, therefore, is only one form of natural selection and does not 

 in any sense subvert or suspend the law of competition and struggle for 

 life and the survival of the fittest. 



By the term fittest must be understood not necessarily the highest in 

 development, but having the best adaptation to the environment, and as 



before stated the alterations sometimes 

 naturally selected for the preservation of 

 a race actually reduce the race in its 

 anatomy and function to a lower plane. 

 For example, the Penguin whose wing 

 is reduced to a fin-like rudiment useless 

 for flying but valuable in swimming and 

 covered with feathers that are but little 

 better than scales, and whose feet can 

 only push him along the ground on his 

 belly not carry him and whose bones 

 are filled with marrow instead of air, is 

 probably a degenerated bird partly re- 

 verted to the Reptilian type. (Fig. 74.) 

 In the Madeira Islands are about 550 

 species of 'beetles. The wings of 200 

 species of these are so far aborted as to 

 be useless for flight. All the species* of 

 twenty-three out of the twenty-nine gen- 

 era found there are in this condition. 

 FIG. 74.-Z&10 Penguin of Patagonia. D arwin p l aus ibly traces the Cause of this 



remarkable fact to selection by the wind which tends to blow out to sea 

 those which were most addicted to flying, thus gradually reducing the 



