Origin of Species… • 15. Recapitulation and conclusion (28)

  •  D a r w i n  (1 8 5 9,  1 8 7 2⁶)  •  15.  R e c a p i t u l a t i o n  a n d  c o n c l u s i o n  •  √it

Glancing at instincts, marvellous as some are, they offer no greater difficulty than do corporeal structures on the theory of the natural selection of successive, slight, but profitable modifications. We can thus understand why nature moves by graduated steps in endowing different animals of the same class with their several instincts. I have attempted to show how much light the principle of gradation throws on the admirable architectural powers of the hive-bee. Habit no doubt often comes into play in modifying instincts; but it certainly is not indispensable, as we see in the case of neuter insects, which leave no progeny to inherit the effects of long-continued habit. On the view of all the species of the same genus having descended from a common parent, and having inherited much in common, we can understand how it is that allied species, when placed under widely different conditions of life, yet follow nearly the same instincts; why the thrushes of tropical and temperate South America, for instance, line their nests with mud like our British species. On the view of instincts having been slowly acquired through natural selection, we need not marvel at some instincts being not perfect and liable to mistakes, and at many instincts causing other animals to suffer.

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[]  C h.  D a r w i n,  ‹T h e  O r i g i n  o f  S p e c i e s›,  J o h n  M u r r a y,  1 8 7 2⁶.
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