It is generally known that many animals possess in a greater or less degree the same senses that we ourselves have: sight, hearing, smell, touch, temperature and so on and that many of them experience such emotions as: anger, grief and joy; but it is not by any means so certain that they have even the elements of reason as we understand that term.
The sense of touch in man is keenest in the finger tips, the lips and the tip of the tongue. In the lower animals the regions of greatest sensitiveness are often different, and in some animals special and very delicate touch organs have been developed; as, for example, the whiskers of the eat and the long hair on the rabbit's lip, by means of which these animals can readily find their way in the densest darkness. The wing of the bat is also very sensitive to touch.
In man the sense of taste is keen and resides in the taste bulbs which cover the tongue and palate. In birds and reptiles the sense of taste is not very well developed. Insects recognize the difference between sweet and bitter, but do not seem to be affected by other flavors. Many animals show an instinctive dislike for certain foods, but it may be more from the sense of smell than from taste, for the two are very closely allied.
In some animals the sense of smell is exceedingly acute. The dog can track his master through the crowded street; the deer recognizes the presence of an enemy very quickly. But birds have little sense of smell, and reptiles also are dull in this respect. Fish differ; it is said that the shark is almost entirely dependent on his sense of smell for his food. In insects this sense is most keenly developed.
Most of the mammals and the birds have a keen sense of hearing. The astonishing manner in which some birds will imitate the songs of other birds testifies to the accuracy of their hearing; but fishes hear little, though it has been proved that they can hear to some extent. Certain insects hear and can distinguish sounds that are pitched higher than the human ear is able to recognize.
The keenness of vision possessed by birds is most remarkable. The swift, flying high through the air, detects on the ground its minute food. The eagle sees his prey from long distances entirely beyond the range of the human eye. Some animals, such as frogs and toads, have keen vision only at short range, and fish seem to be entirely unable to distinguish prey at any great distance from themselves. It is known that certain insects distinguish between colors.
That the higher animals have memory is very certain; a puppy, having been stung by a bee, will ever after avoid the insect, and may even flee at the sound of its humming. Dogs are known to have recognized their masters after years of absence, and they have been known to show strong resentment after many years against an individual who mistreated them.
Animals certainly draw inferences from what they see, but apparently in purely instinctive manner. The best writers seem to doubt whether an animal can put together different facts and establish a conclusion. The extent to which the intelligence of animals goes in this direction, however, is a subject of dispute. Some writers maintain that animals really teach their young; others protest that nothing of the sort is ever done - that the actions of a bird in throwing her young from the nest are purely instinctive, and not with any thought of the young birds' welfare. Many modern writers have taken a different stand and have written exceedingly interesting accounts and imaginative histories of many animals.
