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EVOLUTION AS A SCIENTIFIC EXPLANATION FOR THE DIVERSITY OF LIFE
Charles Darwin used the scientific method to propose a hypothesis for the diversity of life.
Observation: There is a tremendous diversity of life on Earth.
Hypothesis: The diversity of life is a result of Natural Selection: those individuals with
favorable traits will leave more of their genes in the next generation (they are
selected by nature to reproduce and pass on their genes). Over extended time, this
may lead to new species of life and changes in existing species.
Prediction:
(1) If evolution occurs, we would expect organisms to change over time in an
orderly progression, as they adapt to changing environments.
Evidence:
Fossil record provides irrefutable evidence for the transitions of life.
Prediction:
(2) If evolution occurs, then a tremendous amount of time is needed to produce all
of the diversity of life seen today.
Evidence:
Studies of radioactive decay, atomic chemistry, geology provide irrefutable evidence
that the Earth is over 4 billion years old, and that the age of life exceeds 3 billion
years.
Prediction:
(3) If evolution occurs, then the mechanisms of heredity must allow for traits to
be passed on from one generation to the next.
Evidence:
The laws of heredity are completely consistent with evolution by natural
selection. In fact, evolution is an inevitable consequence of genetics.
Prediction:
(4) If evolution occurs, then there must be a mechanism for genes to change over
time.
Evidence:
Mutation is a universal feature of DNA and is easily observable in nature and in
the laboratory.
Prediction:
(5) If evolution occurs, then groups of similar organisms should share common
anatomy and physiology, since they arose from a common ancestor.
Evidence:
Comparative anatomy and comparative physiology are entirely consistent with
natural selection.
Prediction:
(6) If evolution occurs, then there should be evidence of past events written in the
DNA of different organisms.
Evidence:
Studies of DNA provide perhaps the strongest evidence for evolution: closelyrelated organisms share most of their DNA, as evidence of descent from a
common ancestor.