It Is Curious How Often

Given The Fact Of Evolution, One Would Expect The Fossils To Document A Gradual Steady Change From Ancestral Forms To The Descendants. But This Is Not What The Paleontologist Finds. Instead, He Or She Finds Gaps In Just About Every Phyletic Series.

Evolution, Thus, Is Merely Contingent On Certain Processes Articulated By Darwin: Variation And Selection. No Longer Is A Fixed Object Transformed, As In Transformational Evolution, But An Entirely New Start Is, So To Speak, Made In Every Generation.

Isolating Mechanisms Are Biological Properties Of Individuals That Prevent The Interbreeding Of Populations That Are Actually Or Potentially Sympatric.

The Reduced Variability Of Small Populations Is Not Always Due To Accidental Gene Loss, But Sometimes To The Fact That The Entire Population Was Started By A Single Pair Or By A Single Fertilized Female. These 'founders' Of The Population Carried With Them Only A Very Small Proportion Of The Variability Of The Parent Population. This 'founder' Principle Sometimes Explains Even The Uniformity Of Rather Large Populations, Particularly If They Are Well Isolated And Near The Borders Of The Range Of The Species.

Scientific Progress Consists In The Development Of New Concepts.