sit upon her eggs there is a feeling of aversion; while one which fights in defense of her chickens is admired.
Egoistic acts, as well as altruistic acts, in animals are classed as good or bad. A squirrel which lays up a store of food for the winter is thought of as doing that which a squirrel ought to do; and, contrariwise, one which idly makes no provision and dies of starvation, is thought of as properly paying the penalty of improvidence. A dog which surrenders its bone to another without a struggle, and runs away, we call a coward—a word of reprobation.
Thus then it is clear that acts which are conducive to preservation of offspring or of the individual we consider as good relatively to the species, and conversely.
The two classes of cases of altruistic and egoistic acts of animals just given, exemplify the two cardinal and opposed principles of animal-ethics.
During immaturity benefits received must be inversely proportionate to capacities possessed. Within the family-group most must be given where least is deserved, if desert is measured by worth. Contrariwise, after maturity is reached, benefits must vary directly as worth: worth being measured by fitness to the conditions of existence. The ill fitted must suffer the evils of unfitness, and the well fitted profit by their fitness.
These are the two laws which a species must conform to if it is to be preserved. Limiting the proposition to the higher types (for in the lower types, parents give to offspring no other aid than that of laying up a small amount of nutriment with the germ; the result being that an enormous mortality has to be balanced by an enormous fertility)—thus limiting the proposition, I say, it is clear that if, among the young, benefit were proportioned to efficiency, the species would disappear forthwith; and if, among adults, benefit were proportioned to inefficiency, the species would disappear by decay in a few generations (see Principles of Sociology, section 322).
What is the ethical aspect of these principles? In the first place, animal life of all but the lowest kinds has been maintained by virtue of them. Excluding the Protozoa, among which their operation is scarcely discernible, we see that without gratis benefits to offspring, and earned benefits to adults, life could not have continued.
In the second place, by virtue of them life has gradually evolved into higher forms. By care of offspring which has become greater with advancing organization, and by survival of the fittest in the competition among adults which has become keener