Evolution ... Is Opportunistic, Hence Unpredictable.

A Species Consists Of A Group Of Populations Which Replace Each Other Geographically Or Ecologically And Of Which The Neighboring Ones Integrate Or Hybridise Wherever They Are In Contact Or Which Are Potentially Capable Of Doing So (with One Or More Of The Populations) In Those Cases Where Contact Is Prevented By Geographical Or Ecological Barriers.

Every Politician, Clergyman, Educator, Or Physician, In Short, Anyone Dealing With Human Individuals, Is Bound To Make Grave Mistakes If He Ignores These Two Great Truths Of Population Zoology: (1) No Two Individuals Are Alike, And (2) Both Environment And Genetic Endowment Make A Contribution To Nearly Every Trait.

The History Of Science Knows Scores Of Instances Where An Investigator Was In The Possession Of All The Important Facts For A New Theory But Simply Failed To Ask The Right Questions.

Paleontologists Had Long Been Aware Of A Seeming Contradiction Between Darwin's Postulate Of Gradualism, Confirmed By The Work Of Population Genetics, And The Actual Findings Of Paleontology. Following Phyletic Lines Through Time Seemed To Reveal Only Minimal Gradual Changes But No Clear Evidence For Any Change Of A Species Into A Different Genus Or For The Gradual Origin Of An Evolutionary Novelty. Anything Truly Novel Always Seemed To Appear Quite Abruptly In The Fossil Record.

Evolution Thus Is Merely Contingent On Certain Processes Articulated By Darwin: Variation And Selection.