Under crowded conditions the friendly social interactions between members of a group become reduced, and the destructive and aggressive patterns show a marked rise in frequency and intensity.

The response of teenagers to their idols is relevant. As an audience, they enjoy themselves, not by screaming with laughter, but screaming with screams.

Aquatic animals suffer from the disadvantage that they cannot scream when in pain, so we find it hard to gauge the degree of their agony. If fish could scream, angling purely for sport would be outlawed without delay.

Looking back now on the whole sexual scene we can see that our species has remained much more loyal to its basic biological urges than we might at first imagine. Its primate sexual system with carnivore modifications has survived all the fantastic technological advances remarkably well.

There is nothing biologically unusual about a homosexual act of pseudocopulation. Many species indulge in this, under a variety of circumstances.

Artists like cats; soldiers like dogs.

It is interesting that amongst children of preschool age, the more intelligent ones tend to sleep less than the dull ones. After the age of seven this relationship is reversed, the more intelligent schoolchildren sleeping more than the dull ones.