Introduction:
Evolution, the overarching concept that unifies the biological sciences, in fact embraces a plurality of theories and hypotheses.
In evolutionary debates one is apt to hear evolution roughly parceled between the terms "microevolution" and "macroevolution".
Microevolution, or change beneath the species level, may be thought of as relatively small scale change in the functional and genetic constituencies of populations of organisms. That this occurs and has been observed is generally undisputed by critics of evolution.
What is vigorously challenged, however, is macroevolution. Macroevolution is evolution on the "grand scale" resulting in the origin of higher taxa. In evolutionary theory, macroevolution involves common ancestry, descent with modification, speciation, the genealogical relatedness of all life, transformation of species, and large scale functional and structural changes of populations through time, all at or above the species level (Freeman and Herron 2004; Futuyma 1998; Ridley 1993).
Universal common descent is a general descriptive theory concerning the genetic origins of living organisms (though not the ultimate origin of life).
The theory specifically postulates that all of the earth's known biota are genealogically related, much in the same way that siblings or cousins are related to one another. Thus, universal common ancestry entails the transformation of one species into another and, consequently, macroevolutionary history and processes involving the origin of higher taxa.
Because it is so well supported scientifically, common descent is often called the "fact of evolution" by biologists.
For these reasons, proponents of special creation are especially hostile to the macroevolutionary foundation of the biological sciences.
