Last evening, I watched thousands of periodic cicadas swarm our large deciduous trees. Blue jays and starlings turned up to munch on a few while flocks of chimney swifts devoured those that strayed above the treetops.
Gathering to mate, the cicadas' behavior is purely instinctual; like almost all animals, they do not understand its purpose. They have no concept of parents and will never see their children. Yet, their behavior is an important cog in nature's cycle of life.
We humans, endowed with a large brain, have long understood the relationship between sex and procreation. We have also come to recognize the importance of sexual activity beyond its role in perpetuating our species. Unfortunately, certain segments of human society (religious and political) want us to function like cicadas; in their minds, sex is purely a procreative act and any behavior that disrupts this association is sinful, illegal or both.