But although the number of those that were killed was obviously insufficient to produce a change in the biological inheritance of the species, very few birds fly against the wires now.
The young birds must have imitated their elders, who had learnt to avoid the wires; just as the young of many hunting animals are said to learn devices and precautions which are the result of their parents' experience, and later to make and hand down by imitation inventions of their own.
Many of the directly inherited impulses, again, appear both in man and other animals at a certain point in the growth of the individual, and then, if they are checked, die away, or, if they are unchecked, form habits; and impulses, which were originally strong and useful, may no longer help in preserving life, and may, like the whale's legs or our teeth and hair, be weakened by biological degeneration.

Such temporary or weakened impulses are especially liable to be transferred to new objects, or to be modified by experience and thought.
With all these complicated facts the schoolmaster has to deal.

In Macaulay's time he used to be guided by his 'common-sense,' and to intellectualise the whole process.

The unfortunate boys who acted upon an ancient impulse to fidget, to play truant, to chase cats, or to mimic their teacher, were asked, with repeated threats of punishment,'why' they had done so.

They, being ignorant of their own evolutionary history, were forced to invent some far-fetched lie, and were punished for that as well.