What is Evolution?
The Premise
Darwin's Theory of Evolution is the widely held notion that all life is
related and has descended from a common ancestor: the birds and the bananas,
the fishes and the flowers -- all related. Darwin's general theory presumes the
development of life from non-life and stresses a purely naturalistic (undirected)
"descent with modification". That is, complex creatures evolve from more
simplistic ancestors naturally over time. In a nutshell, as random genetic
mutations occur within an organism's genetic code, the beneficial mutations are
preserved because they aid survival -- a process known as "natural selection."
These beneficial mutations are passed on to the next generation. Over time,
beneficial mutations accumulate and the result is an entirely different organism
(not just a variation of the original, but an entirely different creature).
Natural Selection
While Darwin's Theory of Evolution is a relatively young
archetype, the evolutionary worldview itself is as old as antiquity. Ancient Greek
philosophers such as Anaximander postulated the development of life from non-life
and the evolutionary descent of man from animal. Charles Darwin simply brought
something new to the old philosophy -- a plausible mechanism called "natural
selection." Natural selection acts to preserve and accumulate minor advantageous
genetic mutations. Suppose a member of a species developed a functional
advantage (it grew wings and learned to fly). Its offspring would inherit that
advantage and pass it on to their offspring. The inferior (disadvantaged) members
of the same species would gradually die out, leaving only the superior
(advantaged) members of the species. Natural selection is the preservation of a
functional advantage that enables a species to compete better in the wild. Natural
selection is the naturalistic equivalent to domestic breeding. Over the centuries,
human breeders have produced dramatic changes in domestic animal populations
by selecting individuals to breed. Breeders eliminate undesirable traits gradually
over time. Similarly, natural selection eliminates inferior species gradually over
time.
Slowly But Surely...
Darwin's Theory of Evolution is a slow gradual process.
Darwin wrote, "…Natural selection acts only by taking advantage of slight
successive variations; she can never take a great and sudden leap, but must
advance by short and sure, though slow steps." Thus, Darwin conceded that, "If it
could be demonstrated that any complex organ existed, which could not possibly
have been formed by numerous, successive, slight modifications, my theory would
absolutely break down." Such a complex organ would be known as an "irreducibly
complex system". An irreducibly complex system is one composed of multiple
parts, all of which are necessary for the system to function. If even one part is
missing, the entire system will fail to function. Every individual part is integral.
Thus, such a system could not have evolved slowly, piece by piece. The common
mousetrap is an everyday non-biological example of irreducible complexity. It is
composed of five basic parts: a catch (to hold the bait), a powerful spring, a thin
rod called "the hammer," a holding bar to secure the hammer in place, and a
platform to mount the trap. If any one of these parts is missing, the mechanism
will not work. Each individual part is integral. The mousetrap is irreducibly
complex.
Who was Charles Darwin?
Charles Darwin, who was born in 1809, changed our view of how nature developed
with his theory of evolution. He showed that everything evolves, or changes, over
many thousands of years to survive against its enemies and to make best use of
its food resources. He also showed that humans developed from an early ancestor,
which they shared with the ape family. These ideas were very unusual at the
time, and when Darwin published his most famous book, Origin of Species, it
caused an uproar. Many people disagreed with his ideas, because he contradicted
the Bible story of how the earth and all creatures, including Adam and Eve, were
created in six days. Many people now think that Darwin was England's greatest
scientist, although some still argue about his ideas even today. When he died,
Darwin was buried in Westminster Abbey.
Why is the theory of evolution controversial?
From July 10 to 25, 1925, a young science teacher and football coach named John Scopes
stood on trial in Dayton, Tennessee, for reading from the following passage from page
194 of Hunter's Civic Biology (published in 1914) to his high school class:
The great English scientist, Charles Darwin, from this and other
evidence, explained the theory of evolution. This is the belief that
simple forms of life on the earth slowly and gradually gave rise to those
more complex and that thus ultimately the most complex forms came
into existence.
Scopes had broken the Butler Act, which stated:
An act prohibiting the teaching of the Evolution Theory in all the
Universities, Normals and all other public schools of Tennessee, which
are supported in whole or in part by the public school funds of the
State, and to provide penalties for the violations thereof.
Let's examine the events and circumstances of one of America's most famous
court cases, Tennessee v. John Thomas Scopes.
Doug Linder, law professor at the University of Missouri-Kansas City, has
assembled a Web site with excerpts and eyewitness accounts from the Scopes
Trial. Go to "Famous Trials in American History: Tennessee vs. John Scopes,
the 'Monkey Trial'." [http://law2.umkc.edu/faculty/projects/ftrials/scopes/
scopes.htm ]
Read the introduction for an overview. You also may want to read H. L.
Mencken's newspaper reports or the Tennessee statute that made the teaching
of evolution illegal in public schools and universities.
1. On the main page of the Scopes Trial site above, jump to "Trial Pictures and
Cartoons." View the two cartoon sites listed.
2. Explain what you think the artist was trying to depict in each cartoon. Write
your descriptions based on your knowledge of evolution and your
understanding of the circumstances surrounding this trial. You may need to
reexamine the trial facts presented in Professor Linder's Web site to gather
additional background information.
Part B: Draw a Cartoon
1. Become an editorial cartoonist yourself. Create your own cartoon about the
evolution controversy. Your cartoon should include a drawing, a caption, and
an explanation of what you intend to convey.
2. You may wish to view sample editorial cartoons at comics.com before you
draw your own. Avoid putting down people with opinions different from your
own. Use your cartoon to educate, not humiliate.
3. Give your cartoon descriptions and your original cartoon to your teacher for
presentation to the rest of your class.
Part C: Court Decisions
1. Visit the National Center for Science Education's site titled, "Eight Significant
Court Decisions." http://ncse.com/taking-action/ten-major-court-casesevolution-creationism
2. Read about a court case influencing the teaching of evolution in this country
and explain it to the rest of your class.