Biology 100/101
Lecture 27: Evolution and Science


Why teach Evolution?

Evolution is a FACT
AND
and a THEORY

Science as a Way of Knowing
the Natural World

Lecture Syllabus

IB 100/101 Home Page


Why should we study evolution?


Evolution as a fact and a theory

Evolution--the process by which the genetic composition of a population changes over time--is a FACT.

  • This process is all that is required to produce the diversity and similarity of all life on this planet today.

  • Evolution has occurred; it still is occurring; it has been directly observed, documented, demonstrated, and described. Supporting evidence for it is overwhelming (and obtained from a wide range of scientific fields).

The mechanisms by which evolution occurs (e.g., natural selection, mutation, genetic drift) are presented as SCIENTIFIC THEORIES.

  • Several theories have been proposed and debated. It is far from clear how evolution proceeds in every detail.

In summary, Darwin established the FACT of evolution, and proposed a THEORY, natural selection, to explain the mechanism of evolution.


Science as a Way of Knowing the Natural World:

  • A scientist believes that the natural world is a physical reality, but that we can only construct a conceptual view of that reality based upon observation and experimentation.

  • Each of us has our own view of the natural world that is viewed through the lens of our previous experience and knowledge.

  • Science strives to be objective, and is founded in the belief that events can be explained fully by natural causes. Conversely, explanations based in supernatural causes are not considered to be scientific. Rocks of Ages: Science and Religion in the Fullness of Life, By Steven Jay Gould

  • Scientific explanations of phenomena observed in the natural world are called hypotheses (singular: hypothesis).

  • Scientific hypotheses must be testable and falsifiable. If the hypothesis is incorrect it can be tested by experimentation and/or observation and proved to be false.

  • Experimentation and observations can increase our confidence that a hypothesis is a correct explanation of a phenomenon, but can never absolutely prove a hypothesis to be true.

  • Once a hypothesis has been supported by many experiments and/or observations it is considered by the community of scientists to be a theory. (Note that this is very different from the common use of the word, meaning an opinion or a guess.)

  • The conclusions of science are subject to change. New studies, which might utilize new techniques and equipment, may produce new information that leads to the conclusion that previously accepted theories need to be modified or changed entirely.

  • Great science is replaced by greater science.


Lecture Evaluation (ICES) for Ed Dole