| L earning
Objective 14
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14. Briefly describe Darwin's theory of evolution
as a struggle for survival and be able to cite present-day examples.
I. EVOLUTION.
Evolution is change over time. There are many kinds of
evolution: theories about the marketplace, educational strategies and women's
fashions.
II. A Discussion of Biological Evolution.
Biological evolution is a theory which refers to changes
or adaptations of organisms over time.
A."Theory" in science has a different meaningfrom
the everyday meaning. It refers to a scientific idea which has been tested
many times and which has strong support for its veracity.
At the same time, scientists understand that new evidence may appear
and then the theory may be changed or modified in light of this new
information. Again, the modification must go through the rigors of repeated
testing.
B. Along with the cell theory (one of two of the most important theories
in biology) evolutionary theory forms the basis of much interpretation
of biological phenomenon.
C. Hawaiian culture and some expressions of evolutionary ideas.
A. An impressive chant which includes a creation story, the
Kumulipo, was created by Hawaiians about 100
years before Darwin's evolutionary work.
B. In the Kumulipo, life is described as coming
from "life-giving mud-slime" and the creation of life forms starts
with the more simple animal forms and moves to the more complex.
C. Interestingly enough, these two concepts are imbedded in modern day understanding
of the evolution of life. The first cells could have come from shallow puddles
of water. More complex life forms are thought to have come from earlier, simpler forms of life.
Because the Hawaiians, like Darwin, were good observers of nature,
possibly they had a similar recognition of relationships of life forms and their
possible origin.
'amakihi
III. MODERN-DAY EVOLUTIONARY THOUGHT.
Recent evolutionary concepts started with Darwin's
publication of The Origin of Species in 1859.
A. His views were built on many years of research in England
and all over the world. Almost against his will, and certainly contrary
to the opinions of his day, he recognized that biological evolutionary changes
have happened in the past and continues in the present.
B. We cannot go into all the reasons and evidence that convinced
him but we will go directly to his explanation which is the most famous:
survival of the fittest. (For a description of his observations from world-wide travels which lead him to formulate an evolutionary theory, read his book: Diary of the Voyage of the H.M.S. Beagle.)
'anianiau
IV. Summary of the Darwinian Theory of Evolution: Survival of the Fittest.
A. Briefly, many organisms are born, more than there are resources
to support. Only some will survive to reproduce. Those surviving
are more likely to have inherited characteristics that enhance
their survival.
B. An example is a weed, all the same species, found in cow pasture. First both low-growing and high growing ones were present but the high-growing weeds survived
more frequently to reproduce. Hence their greater numbers. After heavy grazing,
most had genes for the low-growing habit. (See figure 14-A) Explain what happened.
Notice how the genetic type of low growing plant existed BEFORE
the change in the environment . (That change was what?) It was NOT caused by the change
but more of its offspring survived to REPRODUCE and pass on that genetic
trait of growing short afterwards.
'i'iwi
V. Some Personal Reflections about the interpretation of the Evolutionary Theory
.
A. To explore some aspects of science and religion differences,
here are some of my own thoughts. These are offered as personal reflections,
and not as concepts on which you will be evaluated.
1. Both religion and science ask questions about the nature
of life and the universe; however, they ask them in different ways. Basically
science asks "how" and religion "why." and religion
"why."
2. Religion, moral codes, ethics and philosophy all concern values. Science
looks at the mechanics of the physical and biological world and asks-- how
does it work?
3. Religion, moral codes, etc. have the important role of determining the
USE of power (and scientific information has incredible power) in
our lives.
Therefore, the use of atomic power or genetic engineering, such as putting
fish genes into crop plants or fertilizing human eggs in test tubes, involve
important human values.
Scientific information will not go away and its process of discovery cannot
be easily stopped. Our lives have been immeasurably enriched by scientific
developments. At the same time there has been, and can be, serious misuse
of this power.
Science by itself is not inherently "good" or "bad".
Its application can be for good or evil or even mixed.
Ultimately, the use of powerful, new scientific information must be guided
by society's careful consideration of values and appropriate checks
and balances which are in concert with our deeply-held, shared values.
B. Today, we understand, unlike Darwin, the basic mechanisms
that underlie inheritance such as the existence genes, DNA and the
pattern of inheritance. We know that all individuals are genetically
unique and produce genetically unique offspring. We also know
that new genetic traits may develop in many ways.
C. The process of selection is not under the control of the organism.
At birth, genetic traits are fixed. The ENVIRONMENT in which the organism
finds itself often does the selection.
D. In Hawai'i there are many different environments -- eleven
or more out of the thirteen major life zones of the world -- making
Hawai'i the place with the greatest number of zones in the smallest area
in the world. These different environments, in turn, have impacted the evolution
of many unusual forms of life found in Hawai'i.
Therefore, Hawai'i is one of the most unusual and interesting examples
of evolution in the world because of different environments and
other factors, like isolation (see discussion below). We can and
do learn much from study of Hawaiian plants and animals which informs us
about the evolutionary process.
E. Some examples of Evolutionary Changes.
1. See examples of the Pasture Weed (Fig. 14-A), Pepper moth,
and Bacteria with antibiotic resistance (See Fig. 14-B). Both demonstrate a difference in the persistence or absence of certain genes over time.
What was the factor in each case which "selected" one gene (which
controls one trait) over the other?
2. Domesticated plants and animals.
Darwin pointed out to his contemporaries that all the strikingly different
breeds of dogs, from Great Danes to toy breeds, come from the one
species of domesticated dogs.
Their change, or evolution, he said, is brought about by artificial
selection, which is determined by humans. What he called natural
selection, is brought about by non-human forces present in the environment.
The same could be said of any highly-developed cultivar of plants and
crop plants. For example, corn, rice and wheat, in their earliest forms
thousands of years ago, were little more than types of grasses with seeds
which had some starch stored in them.
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