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Inherited Traits: Conditions for Natural Selection
Humans evolved the ultimate weapon in the evolutionary arms race: intelligence. We have the ability, through inherited traits such as logical reasoning and language, to share and pool survival-related information and pass it on to future generations through culture. This has allowed humans to get around most defences of most other organisms (although microorganisms still kill millions of our species). We can kill predators such as lions and bears that would easily be able to kill us if we did not have the intelligence to make and use weapons.
For Darwinian evolution by natural selection or sexual selection to proceed, and for traits to be inherited, several conditions must obtain:
1. Selection. Selective pressure must exist. Species evolve to fit imposed environmental conditions (differential fitness, or survival of the fittest).
2. Variation. Genetic variability must exist. Chance mutations and errors in gene replication cause genetic variability to be present among the individuals of a population
3. Heredity. Replication must occur in order to pass on genetic mutations to future generations
The replicating entities are genes. Living things do not replicate. Only their genes replicate through their offspring.
Inherited traits that enhance the ability of future replicating entities to replicate are the adaptations. For an adaptation such as music to continue in future generations, it must confer either naturally-selected survival benefits or sexually selected reproductive benefits (or both). Music probably confers survival benefits in infancy and reproductive benefits later in life.