Notes on the Web -
Unit Six- Part 1
Introduction
to Evolution
Bruce
G. Stewart
General
Objectives and Study Guide
Your
objectives for these Notes on the Web and associated readings and exercises
are:
-
To
recognize the reasons that evolutionary biology is a true science in relation
to the criteria of science and methods of science learned in Unit One previously;
- To state the scientific
and intellectually-based level of acceptance of evolution;
-
To
explain how bias can corrupt logical thinking in considering scientific
explanations with which a person may not personally agree;
- To give an overview of
evolutionary change at the molecular genetics level;
- To summarize the range
of phenomena in nature that are explained naturally within the framework of
evolution as natural mechanisms and products.
Related Textbook Readings:
- Statement from General Biology (BIO 1114)
Johnson and Losos (2008) Chapter 2 has a a consise statement of current
acceptance of evolution. Since it is short, I will quote it here for both
biology and zoology students.
- "The theory of evolution through
natural selection is overwhelmingly accepted by scientists but is viewed
as controversial by some in the general public." You should know
with absolute clarity that this is the case.
- Other textbook and handout readings will be
assigned in later Parts of this Unit Six, but they can be read then.
The Nature of Science
as it Relates to Evolution
Open
Minds are Necessary for Critical Thinking and Scientific Understanding of Biology
Without a
doubt, one of the most difficult exercises in logical thinking is to keep an
open mind and examine evidence that may not support one of our traditional beliefs.
The ability and willingness to objectively examine evidence is a positive sign
of your desire to search for the truth. Scientific study, by its very nature,
can only proceed if we search for truth about the natural world with an honest
and open mind. If you are willing to take this approach as we continue our study
of biology, you may see some wonderful and interesting patterns and processes
that are going on in the world around you. You will better understand nature
and the human species with these new realizations.
|
A free and secular democratic state values education in science. It recognizes
that a strong country needs citizens who are trained in the methods of
science and makes it available through public institutions. Since it protects
the integrity of science and free inquiry it refuses to allow public school
classrooms to be used for religious indoctrination. It especially defends
the integrity of modern biology. The evolution of life is science. It
is more than speculation. It is an established truth, which over one hundred
years of biological research has confirmed.
AMERICANS FOR RELIGIOUS LIBERTY,
1982 (cited in McCollister, 1989) |
|
When researchers compare
the beliefs of the general public about many things that have been scientifically
investigated, they find that the lay public has frighteningly little valid knowledge
of how nature actually works. Test scores and survey results consistently show
that people believe many things that have no scientific basis whatsoever. Consider
the photograph in our earlier chapter on pseudoscience of the sign advertising
iridology services along the highway between Durant and Hugo, Oklahoma.
Iridology is a pseudoscience which claims that you can diagnose specific illnesses
(e.g. you have a problem with your spleen!) by examining the iris of your eye.
Perhaps it is due to the lack of education that some people would be swayed
to have faith in such unproven and fanciful methods of medical diagnosis (see
Worrall 1983 for a complete discussion of iridology). Unfortunately, gullible
individuals with real illnesses may go untreated because they do not seek legitimate
treatments. Thus this is not an innocent harmless belief.
Examples such as the iridology clinic illustrate what happens when
reason is abandoned in favor of illogical belief systems that claim without
evidence to know how nature works. How well we deal with the realities of
nature depends on how good our knowledge is about how nature works. The
social developments of non-functional beliefs about nature are analogous to
cancerous tumors growing in the human body, eating away at the body's fabric
until death results. These kinds of beliefs have been termed
cultural pathogens (Cavalli-Sforza and Feldman 1981, p. 31) because
of the negative effects that they have on human progress. (A pathogen in a
medical sense is a disease-causing organism in human culture a pathogen is a
cultural belief (meme) that has destructive consequences.) In teaching
biological sciences, we seek to dispel such cultural pathogens in order to
produce a better educated, more critical-thinking population. This is the
path to a better future for our children and ourselves.
|
The
Downfall of Agriculture in the Soviet Union: The Case of Lysenko and
Marxism
Some would say that
teachings in science education should give equal time to certain political
and religious beliefs. Some would even go so far as to say that
scientific views that conflict with certain political and religious
beliefs should be censored. However, history teaches us that time
and time again, human ignorance of nature has resulted in disasters, human
suffering and even the downfall of entire cultures.
Take the case of
Trofim D. Lysenko in the Soviet Union in the 1930's, for example (as
described by Futuyma, 1982). Lysenko, a dedicated Marxist,
thought that Mendelian genetics and natural selection could not be true
because this would mean that individual organisms could not improve their
own genetic makeup. This was in conflict with Marxist doctrine which
Lysenko interpreted to mean that nature, like societies and humans, must
be able to improve toward perfection. Thus, he believed in the
inheritance of acquired characteristics. He thought that crops could
be improved for cold climates simply by growing them in colder conditions
for a single generation. Of course, the evidence then as now showed
that this was not the case.
Had Lysenko's views on
biological inheritance simply represented ideas for further testing,
science and agriculture in the Soviet Union could have proceeded on
without disaster. However, Lysenko was a powerful politician who
forced his views into practice and within a decade the best
scientists in the Soviet Union had been imprisoned, executed, or
silenced.(Futuyma 1982). The results were agricultural
disaster and severe setbacks in Soviet biological science for many
decades.
Our beliefs, whatever
they may be, simply do not override the laws of nature. Our fate as
a free democratic society might be no different than the Soviet Union's if
we infect our proven scientific process with pseudoscientific belief
systems (i.e. cultural pathogens). At the very least it will begin
to erode our progress in gaining better understanding of living systems. |
Throughout our lives, many of us have been taught medieval and naive views about
the ways that living systems operate. This is not meant to be a
condescending statement, but rather it is simply a reality of our social
environment in southern Oklahoma. This is not surprising in light of two
basic observations: (A) the typical lay person has very little factual
knowledge about even the most basic processes that occur in and among living
organisms, and (B) many people have had strong religious influences that have
created biased beliefs regarding some areas of legitimate scientific inquiry.
The combination of these two factors often results in naive and unthinking
acceptance of simplistic views of nature. But as we will see, nature does
not mold itself to our preconceived beliefs. Nature does not yield to
popular vote, and the processes of nature will go forward in spite of erroneous
dogmatic claims that this or that just cannot be so. Science is the proven
method of inquiry that has successfully led to greater and greater understanding
of natural processes. As Pulitzer Prize winning author and scientist Carl
Sagan has stated, science delivers the goods. Science is the
only legitimate way to gain factual, functional knowledge about the biological
processes of life.
Perhaps for the first time in your educational experience, you are about to be
presented with an extensive discussion of the scientific truth about one such
process of nature, the biological principle of evolution. Go into this
study with an open mind, reflect honestly about your own public school
background in biology, browse through your basic college biology textbook, and
ask how thoroughly you yourself understand living things. Our textbook
only grazes the surface of scientific knowledge of life. Remember our
study of the scientific process at the beginning of this semester, and that
there are literally hundreds of thousands of peer-reviewed research papers that
provide evidences for particular facts about living things and sound logical
interpretations (i.e. theories) of what those facts mean. There are
mountains of evidence in support of the principles and well-tested theories that
are pertinent to evolutionary study. Thus keep an open mind to the
possibilities that you yourself may be able to see the logical proofs.
Hopefully, your knowledge
has increased this semester in some important areas of biology, such as chemistry
of life, cell biology, and genetics; however, an honest self-assessment would
probable indicate to you that you have only scratched the surface. Yet, for
those of you who have mastered these basic concepts, the foundation has been
laid for you to make an intellectual leap forward in your understanding of life.
Our upcoming lectures supplemented with this handout, your textbook, and some
excellent library readings, will guide you through some of the basics of the
bedrock principle of evolution. We will also learn about false claims that there
is scientific support for one particular religious belief on the origin of species.
Our study of these claims will serve to reinforce our earlier studies of the
nature of scientific inquiry.
A Short Introduction to the Fact of Evolution
What is evolution? Evolutionary
processes are so wide-ranging that it is hard to give a simple answer to this
question, but we will begin with the following partial definition.
Evolution
encompasses the processes by which species change over time spans that exceed
the life of an individual organism. Darwin (1859) called this descent with
modification". Individual organisms do
not evolve! However, there are two primary ways in which offspring
can, in fact, differ genetically (and therefore phenotypically) from their parent(s),
thus allowing evolution to occur:
- New gene combinations
result from meiosis and fertilization during sexual reproduction, thereby
producing offspring that are different from the parents, and
- New gene forms
(alleles) are created by DNA mutation during interphase in reproductive tissue
cells prior to the onset of meiosis, thus allowing the offspring to have unique
genes not found in the parents.
Consider
the implications of the following points.
Scientific
"Fact" #1: DNA codes can and do mutate and cause an organism
that receives the mutated code (during reproduction) to produce a new modified
protein structure.
Scientific
"Fact" #2: a modified protein can manifest itself by causing
a new phenotypic characteristic in the organism that received the modified
DNA code.
Scientific
"Fact" #3: the appearance of a modified protein and any associated
new phenotypic characteristic in the offspring is an example of evolutionary
change.
One
Logical and Certain Conclusion Based on Facts 1 through 3: the accumulation
of small modifications over time result in large evolutionary changes in living
forms.
Some specific known
processes, of which natural selection is only one, by which mutations and certain
genetic combinations are sorted out and molded by nature will be discussed as
we proceed through our unit on evolution. This brings me to a second important
part of the definition of evolution. Evolution also encompasses the
products of biological change. That is, evolution includes
both the:
- mechanisms
of change (past and present), and
- products
of those mechanisms.
These products amaze
even the most casual observer of nature. To biologists and other naturalists,
these products provide and endless source of research material and general interest.
As we have already studied in Unit 2, Marston Bates (1990), the great naturalist/author,
described natural history as:
- being "the
study of life at the level of the individual..."
- having a goal
of discovering "how they react to each other and their environment;"
- having a goal
of discovering "how they organize into larger groupings like populations
and communities;"
- having the major
objective of discovering "the explanation of the diversity of living
things."
Cox (2000) presents a
conservative estimate of 12.5 million species on Earth. What natural
explanation can help us understand the origin of these species? What natural
explanation can help us understand how they maintain their numbers, their
behaviors, their survival, their extinction? Only one
scientifically-supported explanation has fruitfully and consistently provided
answers to these and other important questions--evolution.
| Nothing
in Biology Makes Sense
Except in Light of Evolution
T. Dobhansky 1941 |
We will see the tremendous
explanatory power of the principle of evolution in helping us understand the
natural processes and patterns that we see in nature. We will also review the
extensive evidences from a variety of disciplines (e.g. geology, paleontology,
astronomy, etc.) which are consistent with and support the biological principle
of evolution. But before we get into these topics, let's explore the history
of human thinking regarding the origin of species.
As with all materials throughout
the semester, you will have opportunities to ask questions or ask that any relevant
material from your assignments be discussed in class and/or in threaded discussions
on Internet.
Related Links
As is typical for all of us, learning is reinforced
when we view and study the same materials presented in more than one way. Thus,
I offer you the following links to resources that are covered in this part and
much of the rest of this Unit Six of your Notes on the Web.
Please remember that
there the Internet is full of absolutely worthless web sites on about any scientific
topic. This is especially true about evolution sites since so many anti-science,
anti-evolution, religious-based groups set up websites attacking evolution.
They frequently appear to be talking science when, in fact, they are
espousing pseudoscientific views. You must check the reliability of your
sources and use critical thinking skills to determine whether a source could
be biased (remember our R. J. Reynolds tobacco advertisement exercise!).
If there is not some kind of objective biological science review of the material
presented on a web site, be a healthy skeptic! The three sites I list
above are considered to be good reliable sites.
© 2005, 2007 Bruce G. Stewart