Notes from presentation, 10/11/2006.
Studying biological evolution requires us to note six features:
— There is a diversity of forms and patterns in that diversity
— There is a geological record and patterns in this record
— Organisms tend to be adapted to their environment
— Characters or features of organisms are part of an organized form which is developed anew each generation
— There is change over time and sometimes improvement over observable time.
— All life and change occurs at some place/ in some circumstances
These features can be explored without cutting to the chase of “can natural selection explain every step in biological evolution?” or the chase of “does naturalistic explanation of human evolution undermine religious teachings about right action?” Indeed, the richness of phenomena and particular puzzles stimulate scientific inquiry, which was my primary goal when teaching evolution.
The first four chapters of On the Origin of Species provides a clear exposition of the conceptual structure of natural selection as a means of biological evolution that results in organisms well adapted to their environment (the goal Darwin sets for himself in his introduction).
Part of this argument involves two straightforward deductions:
A. If there exist (inserting some modern terms here):
Variation among organisms in certain characters (chapters 1&2);
(at least partial) Inheritance of the characters (#1&2); and
Hyperfecundity, which ensures that not all can survive to reproduce and that there will be a struggle for existence(#3),
then there will be differential representation of the variant characters over time in lineages of organisms, i.e., modification by descent or (biological) evolution.
B. Now, if there is also natural selection (or survival of the fittest), that is, greater survival and reproduction of those organisms with characters that fit them better to their environment (including mating with potential mates), then evolution will result in improvement of adaptation to conditions of existence (#4).
(worksheet/ tear sheet) – – – – – — – – – – — – – – – — – – – – — – – – – — – – – – — – – – – — – – – – — – – – – —
(Force field analysis of conceptual change or lack of change in students’ concepts.)