Explain Darwin and Wallace's four postulates about the mechanism of evolution.

1) Individuals within species are variable (e.g. eye color: brown, green, blue);

2) Some of these variations are passed onto offspring (e.g. hairline, height, skin color are passed on);

3) In every generation, more offspring are produced than can survive; and (e.g. plants produce thousands of seeds, yet many of them die and a few germinate)

4) The survival and reproduction of individuals are not random; the individuals who survive and go on to reproduce the most are those with the most favorable variation, and they are naturally selected. It follows logically from these that the characteristics of the population will change with each subsequent generation until the population becomes distinctly different from the original; this process is known as evolution.

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