The early part of the twentieth century saw evolutionary theory embattled by disagreements over Darwin's emphasis on natural selection. The then-newly rediscovered work of Gregor Mendel in the ...

Darwin's engine, natural selection, had few supporters: Many people found it distasteful because it seemed to be ruthless and wasteful of life and had no positive, uplifting goal. Some of the ...

Aa Aa Aa Natural selection, genetic drift, and gene flow are the mechanisms that cause changes in allele frequencies over time. When one or more of these forces are acting in a population ...