The Making of Species 
“we consider the habits and life-histories of those 
animals which are more or less gregarious, com- 
prising a large proportion of the herbivora, some 
carnivora, and a considerable number of all orders 
of birds, we shall see that a means of ready 
recognition of its own kind, at a distance or 
during rapid motion, in the dusk of twilight 
or in partial cover, must be of the greatest 
advantage and often lead to the preservation of 
life. Animals of this kind will not usually 
receive a stranger in their midst. While they 
keep together they are generally safe from 
attack, but a solitary straggler becomes an easy 
prey to the enemy ; it is therefore of the highest 
importance that, in such a case, the wanderer 
should have every facility for discovering its 
companions with certainty at any distance within 
the range of vision. 
“Some means of easy recognition must be of 
vital importance to the young and inexperienced 
of each flock, and it also enables the sexes to 
recognise their kind and thus avoid the evils 
of infertile crosses; and I am inclined to believe 
that its necessity has had a more widespread 
influence in determining the diversities of animal 
colouration than any other cause whatever. To 
it may probably be imputed the singular fact that 
whereas bilateral symmetry of colouration is very 
frequently lost among domesticated animals, it 
almost universally prevails in a state of nature ; 
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