Darwins successful theory is best called "evolution by natural selectrion". He put it like this:
- Organisms always produce far more offspring than are needed just to replace the previous generation. This leads to fierce competition between the offspring for scare resources: a "struggle for existence".
- As a result of random changes (which we now trace to mutation of the genes to produce new alleles) these offspring differ from each other: they show variation.
- Only the best-adapted features are passed on to the …