Critical Analysis of Evolution – Grade 10
The following is an evaluation of the "Critical Analysis of Evolution" lesson plan that has been prepared
by the Intelligent Design proponents and adopted by the Ohio state school board. In the event that it is
required as part of the curriculum, many biology teachers may have to deal with it. The concept is not
objectionable--we should, and do, analyze scientific interpretations critically. The difficulty with the
lesson plan is two-fold: first, it elevates "challenges to evolution" to a status that implies that they might
have validity, and second, it offers "suggestions" that follow the traditional ID objectionist strategies.
It is conceivable, however, that Critical Analysis can be achieved with the net result of bolstering support
for evolutionary theory (i.e. the data support the theory), while demonstrating that the "challenges" are
without merit.
This document has been prepared to offer support for those who find that they must use this lesson.
Alternatives to and commentary on the authors' "suggestions" are offered in blue.
The original is from: http://ecology.cwru.edu/ ohioscience/L10-H23_Critical_Analysis.pdf
We offer this analysis to provide instructors with a more complete, and more accurate Teachers' Guide. It
is unfortunate that the suggested answers and guides to scoring that are offered in the original lesson plan
perpetuate errors and misconceptions that can be easily found on the Internet. However, explaining and
correcting these errors and misconceptions in the classroom can prove fruitful for the analysis of scientific
thinking, as well as for understanding evolutionary theory.
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Critical Analysis of Evolution – Grade 10
Ohio Standards Connection:
Lesson Summary:
Life Sciences
Benchmark H
Describe a foundation of
biological evolution as the
change in gene frequency of a
population over time. Explain
the historical and current
scientific developments,
mechanisms and processes of
biological evolution. Describe
how scientists continue to
investigate and critically
analyze aspects of
evolutionary theory. (The
intent of this benchmark does
not mandate the teaching or
testing of intelligent design.)
This lesson allows students to critically analyze five different
aspects of evolutionary theory*. As new scientific data emerge,
scientists' understandings of the natural world may become
enhanced, modified or even changed all together. Using
library and Internet sources, groups of students will conduct
background research for one of the aspects of evolution in
preparation for a critical analysis discussion. Students also
will listen to, and take notes on, their classmates' critical
analyses of evolution theory.
Indicator 23 Describe how
scientists continue to
investigate and critically
analyze aspects of
evolutionary theory. (The
intent of this indicator does
not mandate the teaching or
testing of intelligent design.)
Scientific Ways of Knowing
Benchmark A
Explain that scientific
knowledge must be based on
evidence, be predictive,
logical, subject to
modification and limited to
the natural world.
Indicator 2 Describe that
scientists may disagree about
explanations of phenomena,
about interpretation of data or
about the value of rival
theories, but they do agree
that questioning,
Estimated Duration: Four to six hours
Commentary:
This lesson should be used midway or toward the end of a unit
on evolution. This will allow students to "carry over" their
knowledge of basic evolutionary concepts into this lesson. The
strength of this lesson lies in having students research topics
that interest them about evolutionary biology. Students are
encouraged to consider the research and discuss their findings
with fellow students.
* Actually, these 5 topics are not aspects of evolutionary "theory."
They are some of the pieces of data that have been analyzed in the
development of the theory. In essence, this lesson provides the
authors' views of why they think the data do not support the theory.
Because the lesson does not address many other lines of reasoning,
and does not even address evolutionary theory, it is of limited utility.
response to criticism and
open communication are
integral to the process of
science.
Indicator 3
Recognize that science is a
systematic method of
continuing investigation,
based on observation,
hypothesis testing,
measurement,
experimentation, and theory
building, which leads to
more adequate explanations
of natural phenomena.
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Critical Analysis of Evolution – Grade 10
Pre-Assessment:
• The following items can be used to stimulate dialogue with the students.
• Instruct students to copy the following items from the chalkboard in their science lab notebook.
1. Describe what constitutes an anomaly.
An anomaly is an experimental result or observation that differs from expectation, or that differs
from the existing paradigms that explain the phenonmeon.
2. Why do anomalies exist in science?
Scientists can offer only the "current best possible" explanation for natural phenomena. If this
current best possible explanation is incomplete or erroneous, then new data may conflict with it-and seem like anomalies.
3. Are there any benefits to exploring scientific anomalies?
Understanding the basis for anomalies helps provide additional data that can be used to improve
the "current best possible" understanding. Often such anomalies identify novel situations in
which the system under investigation behaves as expected, but with modifying influences--such
as ribosomal frameshifting induced by hairpin and pseudoknot structures in the RNAs of
retroviruses.
4. How do scientists critically analyze conflicting data?
They repeat their analysis, or ask for confirmation of their findings by other laboratories. If the
conflicting data prove to be reproducible, they look for methodological differences that may
account for the conflicts (such as one experiment being performed at low pH, the other at neutral
pH). If no explanation for the conflict can be found, they re-evaluate their hypotheses for the
explanation of the observations.
5. Define the following terms in your own words:
• Theory
The "current best understanding" of real-world observations, that has been repeatedly examined
from different angles and in different ways, and not yet shown to be erroneous.
• Critical analysis
Careful, skeptical examination. In science, this includes assessment of the data--observations,
experimental results, etc--that support or refute particular hypotheses and theories.
• Natural selection
The process by which individual organisms of different genetic makeup are influenced by
environmental conditions to have more, or fewer, offspring than other individuals in the
population. Note that "environment" includes not only weather, temperature, etc., but also other
individuals within the population (including members of the opposite sex), and individuals of
other species.
• Biological evolution
The process by which the frequency of different versions (alleles) of different genes changes in a
population of organisms. Changes in gene frequency can occur by genetic drift, or can be
influenced by selection--either natural selection (not involving humans) or by human intervention
(as in crop breeding or the breeding of different types of dogs).
• Macroevolution
Large evolutionary changes, usually considered to be dramatic morphological changes or
speciation. This may require many generations of selection, or can occur by mutation of
regulatory genes that control developmental processes.
• Microevolution
Small evolutionary changes, usually affecting the characteristics of individuals within a
population. A single natural selection event can be said to cause microevolution.
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Critical Analysis of Evolution – Grade 10
Scoring Guidelines:
Collect pre-assessments and evaluate for indication of prior knowledge and/or misconception. Sample
definitions for question five in the pre-assessment include, but are not limited to, the following:
• Theory
A supposition or a system of ideas intended to explain something, especially one based on general
principles independent of the thing to be explained.
This is somewhat vague, but almost adequate. Unfortunately, it omits the critical part of the
definition: that it is an explanation that has survived repeated tests. [Note that the authors'
definition prepares students to be receptive to the deceptive anti-evolution argument that
"homology" is defined as "coming from a common ancestor," but is used to infer common
ancestry. This argument is incorrect, but seems plausible on short notice.]
• Critical analysis
The separation of an intellectual idea into its constituent parts for the purpose of a careful, exact
evaluation and judgment about those parts and their interrelationships in making up a whole. (This
definition combines the definition for critical and analysis.)
Adequate.
• Natural selection
The principle that in a given environment, individuals having characteristics that aid survival will produce
more offspring, and the proportion of individuals having such characteristics will increase with each
succeeding generation.
Again, this is adequate. [Note that this definition is acceptable to those who accept
microevolution because it has been proven beyond a shadow of a doubt, but is not acceptable to
all types of Biblical creationists.]
• Biological evolution
Changes in the genetic composition of a population through successive generations.
Again, this is adequate.
• Macroevolution
Large-scale evolution occurring over geologic time that results in the formation of new taxonomic groups.
This is inaccurate. The formation of new taxonomic groups (such as species) can easily occur
rapidly and without large-scale evolution. For example, spontaneous formation of tetraploid
plants results in plants that cannot interbreed with their progenitors (and are thus a new species),
yet look similar because no "large scale" changes occurred.
• Microevolution
Evolution resulting from a succession of relatively small genetic variations that often cause the formation
of new subspecies.
This, too, is inaccurate. Whether microevolution results in slight differences within the same
species, or results in subspecies, or results in populations that cannot interbreed with one another
(and are thus new species) depends upon which genes are involved. Microevolution is the
process of selecting "a change in the DNA" on the basis of the characteristics that the DNA
produces in the organism, or even genetic drift, in which case there is no selection. If the gene
that changes affects egg/sperm recognition, and complementary mutations occur in the opposite
sex, a new species can arise without any obvious morphological differences.
Post-Assessment:
• Describe why scientific critical analysis of evolution is important.
It helps us recognize why the theory of evolution is so strongly supported by the data, and helps
us see why intelligent design theory is non-scientific.
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Critical Analysis of Evolution – Grade 10
• Describe three major pieces of evidence used to support evolution and explain why these pieces are
important.
1. DNA sequence similarity: The fact that identical DNA sequences (e.g. within the ribosomal
RNA genes) have been found in all organisms yet examined indicates that all species are
genetically related. The differences in DNA sequences among organisms are less for organisms
that are more similar in many respects, while the differences are greater for organisms that are
less similar. This is a finding that is independent of evolutionary theory, but is predicted by it.
2. Evolution of AIDS virus and influenza virus have been documented by analysis of DNA
sequences. For AIDS, virus from early and late in an infection of a single individual show
differences in sequence. In particular, the portion of the gene responsible for sensitivity to AZT
shows rapid changes when patients are treated with AZT, resulting in AZT-resistant virus, exactly
as predicted by evolutionary theory. For influenza, virus from different individuals from many
years shows the gradual accumulation of DNA sequence changes. Similar changes occur with
time in viruses that infect birds, but the changes are different from the changes that occur in
human-infecting virus. When a bird virus "hops" to humans, as occurred in 1968, a major
pandemic can occur because the new HA sequence is so different from the recent human viruses
that humans lack cross-immunity to it from previous years. The evolution of viruses
demonstrates exactly what is predicted by evolutionary theory, but on a time scale that is easily
followed by humans. It offers proof of the basic principles, even for those who say that it is
necessary to observe phenomena in order for them to be "scientific."
3. Phylogenetic trees based on DNA sequence match those based on morphological
characteristics. Such trees show nothing but similarities and differences (one can make a similar
tree using furniture), and do not identify causal mechanisms. One inference for how such
similarities and differences came about is that the Designer purposely made them fit such trees,
consciously making the DNA and the morphological characterstics fit the same pattern. Another
is that common evolutionary descent is responsible for both features (morphological and genetic).
An independent test of such trees is examination of the fossil record, which shows that organisms
appeared in the fossil record in exactly the order predicted by the DNA-based tree. Again, there is
confirmation from several lines of evidence that are independent from one another.
• Describe three major pieces of evidence used to challenge evolution and explain why these pieces are
important.
1. It is often suggested that "no one was there to see it happen," so the theory of evolution is "not
science." This is important because it appeals to peoples' common-sense view of the world.
However, there are many things that occur when no one is looking. If I find a tree in the forest, I
could conclude that it was specially created the day before, or I can infer from other types of
evidence that trees grow from seeds, and therefore it is likely that this one did, too. Absence of
contemporary observers turns out to be a silly argument. Anyone familiar with forensic analysis
in crime scene investigations will recognize this.
2. It is often suggested that some biological structures are too complex to have happened by
evolution. They are said to be "irreducibly complex." This is important because it, too, appeals
to our common-sense view of the world. However, every biological system that has been
examined (for example the eye) has been shown to have more primitive versions in more
primitive organisms. These so-called irreducibly complex structures are not irreducibly complex.
Partial, less functional progenitors exist. This argument appears not to be valid. [Note that this
type of argument has been extended to the biochemical level, which makes it harder for the
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Critical Analysis of Evolution – Grade 10
average person to evaluate the validity of the argument. It is true that we have not found partial
ribosomes, but we have learned that the catalytic center of the peptidyl transferase is the
ribosomal RNA itself, not the proteins. That is, the complexity of the ribosome is above and
beyond the fundamental function. Thus, ancient ribosomes with fewer proteins can easily be
imagined, with the prediction that they would be less efficient but not non-functional.] Of course,
we would not expect to find the true evolutionary precursors of ancient, conserved structures in
extant organisms, because every organism alive today is equally far removed from the earliest life
forms. Everything has had millions and millions of years for evolutionary modification.
3. It has been stated that something as complicated as a living animal (or a human) cannot have
occurred by random chance. A whirlwind blowing through a junkyard simply will not assemble a
Boeing 747 by random reassortment of the pieces of junk. This is important because it is true,
and again appeals to common sense. However, this is not what the theory of evolution is based
upon. Indeed, mutations occur at random, but selection is not random. This has been
demonstrated over and over again. Therefore, this argument sets up a "straw man" in order to
destroy it. It pretends evolution works by a mechanism that is different from what it is.
• Compare and contrast the supporting and challenging information regarding the aspect of evolution you
studied.
The supporting information is based on data. The challenging information is based on misconceptions
and conjecture.
• Evaluate the scientific data supporting and challenging areas of evolution in light of the scientific
method. In other words, is the data that is used to support or challenge evolution consistent or
inconsistent with the scientific method? Are there any limitations? (NOTE: steps of scientific method:
Observation, hypothesis, test, retest and conclusion)
The difficulty here is that "The" Scientific Method does not really exist. See:
http://www.nsta.org/positionstatement&psid=22 which states, "Although no single universal step-by-step
scientific method captures the complexity of doing science, a number of shared values and perspectives
characterize a scientific approach to understanding nature. Among these are a demand for naturalistic
explanations supported by empirical evidence that are, at least in principle, testable against the natural
world. Other shared elements include observations, rational argument, inference, skepticism, peer review
and replicability of work." That is, some fields use the method mentioned here, but many others do not.
Even so, the notion of "test and retest" can be applied. The tests are in the form of predictions, crosschecks with other independent data sets, etc. When applied to evolutionary theory, these prove to be
validated. It is difficult to test the "alternates to evolution," such as intelligent design, because the
designer is not available for analysis. However, we can ask whether there are alternative natural
explanations for the data, such that there is no compelling need to appeal to supernatural intervention.
There always are such alternatives.
Instructional Procedures:
Instructional Tip:
Scientists make a distinction between two areas of evolutionary theory. [they actually make many
distinctions] First, scientists consider mutation, natural selection, genetic drift and gene flow (immigration
and emigration) as the processes that generate evolutionary changes in organisms and populations.
Second, the theory of universal common descent describes the historical pattern of biological change.
This theory maintains that all living forms have descended from earlier living forms and ultimately from a
single common ancestor. Darwin envisioned the theory of universal common descent as a necessary result
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Critical Analysis of Evolution – Grade 10
of evolutionary changes in organisms and populations, and represented it in his branching tree of life.
Students will investigate and analyze these two areas of evolutionary theory in this lesson.
It is probably important to make this distinction because creationists have been forced, by
overwhelming data, to accept microevolution. It is the concept of universal descent--and the
descent of humans from non-human ancestors--that they feel is dangerous. One should note, of
course, that the Tree of Life is really nothing more than a pictorial representation of differences
between organisms (a pictorial representation of descriptive facts). Those organisms that are
most similar are closer together on the tree. We can generate such a tree from any set of things,
of any origin. The challenge is to explain how the pattern described in the tree came to be.
Evolutionary descent is one explanation. Special creation or design could be an alternate
explanation, but one that is not testable. It is also necessary to imbue the designer or creator with
a sense of humor, inasmuch as the organisms were created specifically to fit a pattern of
similarities and differences that so closely matches the predictions of common descent.
In addition to the distinctions between different areas of evolutionary theory, scientists also find it helpful
to distinguish amounts of biological change or evolution. Microevolution refers to evolution resulting
from a succession of relatively small genetic variations that often cause the formation of new subspecies.
Macroevolution refers to large-scale evolution occurring over geologic time that results in the formation
of new taxonomic groups. These terms are helpful distinctions in the course of analyzing evolutionary
theory. These terms have appeared in OhioLink research databases, numerous Internet sites, and biology
and evolution textbooks. Though "micro" and "macro" are prefixes, it is quite clear that the scientific
community recognizes and acknowledges the distinction between the words. There is more research on
microevolution than there is on macroevolution. To help ensure academic clarity, this lesson distinguishes
between microevolution and macroevolution. Teachers may need to provide support to students to help
them understand this distinction throughout the lesson.
As noted above, these definitions of macroevolution and microevolution are incorrect. Although
it is clear that scientists distinguish between the terms, it is not clear that there is a distinction
between the processes. Multiple accumulated steps of microevolution can lead to
macroevolution. Alternatively, mutation of regulatory genes, or alteration of expression patterns
of regulatory genes can give rise to what has been called macroevolution--through the
mechanisms of microevolution. It should be noted that the terms were coined before the
mechanisms were known. Now that we know much more about mechanisms, it is not at all clear
that the terms retain any validity.
Teachers will need to provide students with correct information to help them understand this
lesson.
Student Engagement
1. Write the following statement on the chalkboard or
overhead:
Anomalies are ideas in science that depart from the general consensus of the time. Many anomalies occur
in science. In an effort to determine the cause of this deviation, scientists conduct research to collect data
that will explain the phenomena. As the evidence mounts by careful analysis of the data, original ideas
may change from one scientific understanding to another.
As noted above, this is not the correct definition of "anomaly." A correct definition would be an
instance in which data conflict with previously-existing ideas. This point will be elaborated upon
below.
2. Ask students to think through the following science topics and discuss where anomalies led to the
collection of data that further explained the phenomena and contributed to changing scientific
understandings.
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Critical Analysis of Evolution – Grade 10
• Spontaneous generation versus biogenesis
Several pieces of data could be used. One example is Francesco Redi's observation that flies must contact
meat in order for maggots to appear on the meat.
Prevailing wisdom was once that spontaneous generation was the norm. The anomalous data
came from the demonstration that flies (or mice or bacteria) appear only if their parents are
allowed access to the location in which they appear. The anomaly, in this case data, proved the
prevailing idea to be wrong. [We should note, of course, that spontaneous generation has nothing
to do with evolution, though anti-evolutionists often use the term, spontaneous generation, to
refer to scientific hypotheses concerning the origin of life.]
• Geocentric versus Heliocentric
Several pieces of data could be used. One example is the observed phases of Venus.
Prevailing wisdom was once that the Earth was the center of the universe. Indeed, Biblical
information indicates that it is, and that it is flat. As it became possible to identify planets and
follow their motion, it became more and more difficult to explain their behavior on the basis of
the geocentric model. The data from the real world were anomalous relative to the ideas
presented in the Bible. In time, however, the evidence became overwhelming, and the
heliocentric theory was accepted.
• Global warming versus non global warming
Several pieces of data could be used. One example is the observed increasing size of the hole in the
ozone layer.
It's not clear what is meant by "non global warming." If it means "local warming" as opposed to
global, it would be a simple matter to demonstrate that many "locales" show warming, thereby
confirming that the warming trend is global. If it means "there is no global warming," then it is
difficult to find data in support of this notion. The only data that conflict with global warming
seem to be the statements of certain Congressmen and Administration officials who insist that
"more research is needed." The ozone hole, of course, is not related.
3. Ask students to cite additional areas where critical analysis is needed by the scientific community.
One of the most important would be the biological development of sex and gender, in particular
as it relates to behavior. There is considerable evidence that brain "wiring" is sexually dimorphic,
and that it can be influenced by chromosomal and hormonal cues. The evidence is very close to
providing an explanation for gay/lesbian behavior. For example, a male with female brain
structure that resulted from prenatal development would be expected to show "gay" behavior.
This would indicate that this type of behavior is not a lifestyle choice, but is rather determined
epigenetically (perhaps by chemicals that act as endocrine disrupters) before the individual can
make a conscious choice. It seems that it is essential to consider this issue via critical analysis,
since the "lifestyle choice" hypothesis appears not to hold up to scrutiny. Is being born gay part
of God's plan?
Teacher Presentation
4. Present supporting and challenging information for five aspects of evolution found in Attachment A.
This will give students background information concerning both supporting and challenging evidence.
Students can use this information to focus their research. Alternative strategies for beginning this lesson
could be to engage students in a Socratic discussion or a mini-lecture. See the Web site for student
research at the Los Alamos National Laboratory for guidelines on the Socratic method. The Web
address is listed in the Technology Connections section.
There are many aspects besides these 5, but all can be analyzed. However, current pedagogical
research indicates that "giving students background information" is less effective than providing
them with issues that engage them, and invite them to use inquiry strategies to learn about them.
Indeed, it is best to give students the data, and let them determine what the best explanation is--
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Critical Analysis of Evolution – Grade 10
rather than lead them directly to "challenging information" which may be presented inaccurately,
or "supporting information" which may be a summary of someone else's conclusions.
Student Research
5. Form groups consisting of two to four students. Assign each group a number to help monitor their
activities and assignments during the lesson.
This can't hurt.
6. Allow the groups to pick (or assign) one of the five aspects of evolutionary theory. Assign two groups
to research each aspect. The aspects are:
"Research" is the key, here. Students at this level have insufficient background and far too little
time to do original research into these issues. Presumably, the research that is intended here is
expected to be a library or web search of what others have written. This raises the very difficult
question of how students can distinguish accurate information from inaccurate. Extensive
research might enable students to assess each claim that is made, by looking up the original data
and assessing it for themselves--but there is insufficient time even for this. Teachers will need to
help students sort through different types of claims that they may come upon in their searches.
Aspect 1: Homology (anatomical and molecular)
This will be somewhat difficult, since the term has been used in many different ways. Only
recently has there been an effort to standardize the definition. Thus, students are likely to find
conflicting information, in which the authors use the term in different ways. The teacher will
need to be aware of this.
Aspect 2: Fossil Record
Much is known about the fossil record. This will be a good topic.
Aspect 3: Anti-Biotic Resistance
Antibiotic resistance is one of the most clearly documented evolutionary events. It also is
tremendously important for medical and agricultural understanding. This will be a good topic.
Aspect 4: Peppered Moths
An old, but classic example of selection. It is in the textbooks.
Aspect 5: Endosymbiosis
A hypothesis that was at one time hotly disputed. An historical examination of this issue would
be useful to illustrate the way that science works. What initially seemed to be a wacky idea
eventually proved to be correct.
7. Distribute Attachment B, Investigative Worksheet, to help guide research. Allow time for the two
groups assigned the same aspect to research their topic by answering questions on the Investigative
Worksheet. Have groups use the worksheet as a guide to help them research supporting and challenging
data on their particular aspect of evolution. The worksheet will help students organize their ideas and
facilitate their critical analysis.
Worksheets are commonly used in this way. Unfortunately, the listing of "support" and
"challenges" in this way gives the misguided impression that the challenges are as valid as real
data. Nonetheless, teachers can help students learn what the challenge really is, and help them
phrase their statements accurately. [See discussion of "challenges" above.]
Instructional Tip:
Attachment B, Investigative Worksheet, has questions that can be applied to all five aspects. This will
help students become familiar with the data, and therefore be able to critically analyze the evidence for
either the supporting side or the challenging side. As they complete the worksheet, the group members
may all work together on each question, or divide the questions among themselves and then share their
findings as a group.
Here, the word "data" is used to refer to the information that students find on the web. It does not
refer to the scientific observations whose interpretations the different authors discuss. By using
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Critical Analysis of Evolution – Grade 10
the term "data" imprecisely this way, the authors of the lesson plan imply that written arguments
are the critical, deciding factor in evolutionary biology. They are not. The original observations
are.
Critical Analysis Activity
9. Allow the students to spend time researching and preparing for the critical analysis activity on both the
supporting and challenging information. Prior to the activity, randomly determine which of the two
groups will present supporting information and which will present challenging information. You may
have groups draw cards to help objectively determine if they will research the supporting or challenging
information.
By segregating the investigation of supporting information and challenges, students are treated
differentially. This is not recommended. Those students who investigate the "wrong" issues will
not learn the accurate information effectively. All students should investigate both.
Instructional Tip:
Encourage all students to participate in the critical analysis activity because the experience will be a
learning opportunity. Be prepared, however, to distribute alternate assignments to students who do not
want to participate.
Why would students not want to participate? Should we provide alternate assignments to
students who do not want to learn algebra? All students should study evolution.
10. Hand out Attachment C, Critical Analysis Rubric, to help students understand the materials they need
to prepare and how they should conduct their presentations.
A scoring rubric is fine. Teachers may want to prepare their own if they think a different format
would be helpful.
11. Ask each group to write out their introduction, outline their presentations and write their conclusions.
Have students practice their presentations to be sure that they are concise.
As noted above, differential treatment of students is inappropriate. Therefore, each group will
need to prepare a critical comparison of the supporting data and the challenges.
12. Have two pairs of students address each aspect. Have one group present the data that support an
aspect and the other group present the data that challenge the aspect. Flip a coin to decide which group
begins the critical analysis activity. Instruct each side to present its research. The teacher will serve as
facilitator to assure that the groups remain on task and on time. There are no winners or losers in this
critical analysis activity. This is a sharing of the results of their research concerning evolution.
A group discussion might be more effective, asking for a list of supporting data, and a list of
challenges. It will then be possible to assess the data, and consider the validity of the challenges
and whether data exist to support them. It is possible that, if some groups present data, and others
present anti-evolution conjecture, that the class will get into an argument. Dispassionate
discussion is more helpful.
Note that here, the term "data" refers to the actual observations from the field, and not to
statements that various authors have made. This is critical! Indeed, for each assertion made, it
would be valuable to ask "what's the data?"
13. Encourage students to actively participate as they critically analyze their assigned aspect. To ensure
that they remain engaged as they watch and listen to the other groups, distribute copies of Attachment D,
Critical Analysis Worksheet, and have them take notes. At the conclusion of the lesson, this worksheet
will be turned in for a grade.
Differentiated Instructional Support:
Instruction is differentiated according to learner needs, to help all learners either meet the intent of the
specified indicator(s) or, if the indicator is already met, to advance beyond the specified indicator(s).
• Make a copy of the post-assessment available to all students at the beginning of the lesson. This will
allow students to clearly understand what is expected from them.
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Critical Analysis of Evolution – Grade 10
It is not clear that access to the post-assessment enables the post-assessment to retain its validity.
• Have students submit an outline of their presentation, including introductory remarks and conclusion, to
assist in their organizational skills. This allows the teacher to give feedback to the students and to help
prepare them for the critical analysis activity.
Extension:
Have students consider other aspects of evolutionary biology that are critically analyzed by scientists.
Possible topics include:
• Hox (homeotic) genes
A complicated topic at best. Students will need to understand the role of regulatory genes in
development, and the role of the regulation of regulatory gene expression. It is changes in the
regulation of Hox genes, rather than changes in the Hox genes themselves, that accounts for most
of the alterations in Hox-dependent morphology.
• Biogeography
This, too, is complex. It addresses why different species live where they do, and reflects a great
many processes, of which evolution is but one. This is not a good topic for analysis of evolution,
per se.
• Vestigial organs
This topic is probably accessible to students at this level, although the common misconception
will be that organs become vestigial because the species "knows" that the organ is no longer
needed, rather than because the lack of use of the organ provides no selection against mutations
that affect the organ. This is a subtle, but important distinction that teachers will need to make
clear.
• Four winged fruit fly
The value of this multiple mutant is limited. It demonstrates that regulatory genes control
development, and indicates that in this species, the relevant Hox genes control pathways of
development that lead to particular body parts. Since the triple-mutant fly involves Hox gene
mutations (indeed, mutations in the regulation of the Ubx gene) this issue can really be addressed
only after mastery of the Hox genes listed above. That Ed Lewis was able to produce the fly by
combination of different mutations does not indicate that natural evolution occurred via this
intermediate (though anti-evolutionists portray biologists as claiming that it does). The mutant
fly demonstrates that changes in control genes can change development, and merely indicates
which genes are involved.
• Galapagos finches
These are the classic species that led Darwin to his fundamental insight that if a population is
separated from other populations, it may follow its own evolutionary path. The recent
demonstration of changes in beak dimensions as a result of differing selection pressures is an
elegant proof of the mechanism of natural selection.
Interdisciplinary Connections
Social Studies Skills and Methods Standard
Benchmark A Evaluate the reliability and credibility of sources.
This is particularly important, and is in many respects the key to this lesson.
Indicator 1 Determine the credibility of sources by considering the following:
a. The qualifications and reputation of the writer;
With what groups is the writer affiliated?
What is the agenda of each such group?
What else has the writer published, and in what venues?
11
Critical Analysis of Evolution – Grade 10
What is the writer's history (education, for example).
b. Agreement with other credible sources;
This is a little tricky, since new ideas often do not agree with other sources, even if the eventually
prove to be correct. It might be better to ask in what ways the writings agree or disagree with
other credible sources. Note that assessing credibility of these other sources requires going
through this same list of questions for each source.
c. Recognition of stereotypes;
Stereotypes should not be relevant here, since the issue is with the evidence itself, and not with
the writer's judgement of others. However, if the writer does judge others, this can certainly be a
clue to the writer's biases.
d. Accuracy and consistency of sources;
If the writer uses sources, this can be useful--but requires that students look up each of the
sources, and apply this same set of questions to each source.
e. The circumstances in which the author prepared the source.
We might rephrase this as "what was the author's agenda in writing this piece?"
English Language Arts Research Standard
Benchmark B Evaluate the usefulness and credibility of data and sources.
Indicator 3 Determine the accuracy of sources and the credibility of the author by analyzing the sources'
validity (e.g., authority, accuracy, objectivity, publication date and coverage, etc.).
This raises the same issues as above.
Benchmark C Organize information from various resources and select appropriate sources to support
central ideas, concepts and themes.
This is excellent and should be done.
Indicator 2 Identify appropriate sources and gather relevant information from multiple sources (e.g.,
school library catalogs, online databases, electronic resources and Internet-based resources).
Note that "online databases, electronic resources, and Internet-based resources are, at this time, all
internet-based. It might be useful to add college and university libraries as well, since much of
the work in this field is carried on in these institutions and is published in journals in their
libraries.
Indicator 4 Evaluate and systematically organize important information, and select appropriate sources
to support central ideas, concepts and themes.
This seems to be the specific indicator that does what the Benchmark describes.
Materials and Resources:
The inclusion of a specific resource in any lesson formulated by the Ohio Department of Education
should not be interpreted as an endorsement of that particular resource, or any of its contents, by the
Ohio Department of Education. The Ohio Department of Education does not endorse any particular
resource. The Web addresses listed are for a given site's main page, therefore, it may be necessary to
search within that site to find the specific information required for a given lesson. Please note that
information published on the Internet changes over time, therefore the links provided may no longer
contain the specific information related to a given lesson. Teachers are advised to preview all sites
before using them with students.
For the teacher: attachments, resource materials such as the Internet, World Wide Web, library resources
For the student: attachments, resource materials such as the Internet, World Wide Web, library resources
12
Critical Analysis of Evolution – Grade 10
Vocabulary:
• Biological evolution
• Critical analysis
• Evolutionary theory
• Macroevolution
• Microevolution
• Natural selection
• Theory
It is essential that students recognize and learn that these terms (as with most terms) have more precise
meanings in science than in conversational English. This is an essential aspect of learning biology, just as
learning the language is essential for any field. In general, it will be necessary to find the scientific
definitions of these terms in scientific resources, such as glossaries of textbooks, and not in standard or
online dictionaries. The latter usually contain the definitions as used in conversational English.
Technology Connections:
• Have students use the Internet to search for resources on evolutionary biology.
In addition to the Critical Analysis link, this includes a brief summary of the site
http://www.stephenjaygould.org
Information on Stephen J. Gould, but not a discussion of evolutionary mechanism per se
http://www.arn.org
A site dedicated to the promulgation of Intelligent Design ideology
http://www.objectivityinscience.org
A site dedicated to the introduction into science classes of anti-evolution ideology
http://www.origins.org
A site dedicated to the idea that the Biblical account of creation is fact
http://genetics.nbii.gov
National Biological Information Infrastructure site, primarily addressing issues of biodiversity,
and not evolution per se.
http://www.ucmp.berkeley.edu/history/evolution.html -- University of California, Berkeley museum of
paleontology evolution pages
• Access the Web site for student research at the Los Alamos National Laboratory, at http://set.lanl.gov,
for guidelines to the Socratic Method. From the homepage, navigate to Programs, and then Critical Issues
Forum.
Additional sites that should be listed:
http://evolution.berkeley.edu/ -- Understanding Evolution pages at UC Berkeley
http://www.natcenscied.org/ -- National Center for Science Education
http://www.ncseweb.org/resources/articles/9375_statements_from_religious_orga_12_19_2002.asp -statements from religious organizations, providing clear evidence that evolution and
religion are compatible.
http://www.pbs.org/wgbh/evolution/ -- The Public Broadcasting System's evolution pages
http://www.talkorigins.org/ -- Talk.Origins Archive, a collection of articles about the
creation/evolution controversy
Research Connections:
Marzano, R. et al. Classroom Instruction that Works:
Research-Based Strategies for Increasing Student Achievement. Alexandria: Association for Supervision
and Curriculum Development, 2001.
• Identifying similarities and differences enhances students' understanding of and ability to use
knowledge. This process includes comparing, classifying, creating metaphors and creating analogies and
may involve the following:
13
Critical Analysis of Evolution – Grade 10
• Presenting students with explicit guidance in identifying similarities and differences.
• Asking students to independently identify similarities and differences.
• Representing similarities and differences in graphic or symbolic form.
• Summarizing and note taking are two of the most powerful skills to help students identify and
understand the most important aspects of what they are learning.
General Tips:
• Students should use school library resources such as InfOhio's Access Science and EBSCO to locate
information on aspects of evolutionary theory.
EBSCO is an electronic journal service, and will be of little help to secondary students who do not yet
know which articles in which journals have the scientific data they need. InfOhio is password-protected,
and cannot easily be evaluated.
• See the following resources for information that supports or challenges different aspects of evolution.
A great many of the evolution references here are in journals that will very likely be inaccessible to
students, either physically (no library nearby that carries the journal) or scientifically (most are written for
a research audience familiar with the research methods in the field as well as the specific terminology
used). The anti-evolution articles, by contrast, are written for a lay audience, and are thus quite
accessible, even if they do not provide all of the scientific data needed to evaluate their claims. It might
be more helpful for students to look at some of the books listed on Massimo Piglucci's handout
identifying his favorite readings.
1. Ayala, Francisco, "The Mechanisms of Evolution." Scientific American, 239:3 (1978): 68.
2. Brickhouse, Nancy. "Diversity of Students' Views about Evidence, Theory." Journal of Research in
Science Teaching. 37:4 (2000).
3. Carroll, Robert L. (1997/98). "Limits to Knowledge of the Fossil Record". Zoology. 100 (1997/98):
221-231.
4. Carroll, Robert L. "Towards a New Evolutionary Synthesis." Trends in Ecology and Evolution 15
(2000): 27-32.
5. Cherfas, J. "Exploring the Myth of the Melanic Moth." New Scientist. (1986): 25.
6. Chinn, Clark. "An Empirical Test of a Taxonomy of Responses to Anomalous Data in Science."
Journal of Research in Science Teaching. 35:6 (1998).
7. Chinn, Clark. "The Role of Anomalous Data in Knowledge Acquisition: A Theoretical Framework and
Implications for Science Instruction." Review of Educational Research. 63:1 (1993): 1-49.
8. Darwin, Charles. On the Origin of Species: A Facsimile of the First Edition. Cambridge: Harvard UP,
1975.
9. Denton, Michael. Evolution: A Theory in Crisis. Bethesda: Adler and Adler, 1986.
10. Doolittle, W. Ford "Uprooting the Tree of Life," Scientific American (2000): 90-95.
11. Erwin, Douglas. "Macroevolution is More Than Repeated Rounds of Microevolution," Evolution &
Development 2 (2000): 78-84.
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Critical Analysis of Evolution – Grade 10
12. Erwin, Douglas. "Early Introduction of Major Morphological Innovations," Acta Palaeontologica
Polonica 38 (1994): 281-294.
13. Evans, Margaret E. "The Emergence of Beliefs About the Origins of Species in School-Age
Children." Merrill- Palmer Quarterly. 46:2 (2000): 221-253.
14. Faust, David. The Limits of Scientific Reasoning. Minneapolis: University of Minnesota Press, 1984.
15. Fitch, W., and E. Margoliash, "Construction of Phylogenetic Trees." Science 155 (1967): 281.
16. Gilbert, Scott F., et al. "Resynthesizing Evolutionary and Developmental Biology," Journal of
Developmental Biology 173 (1996): 357-372.
17. Gould, Stephen J. "Abscheulich (Atrocious), Haeckel's Distortions did not Help Darwin. Natural
History. (2000).
18. Jeffares, D. "Relics from the RNA World." Journal of Molecular Evolution 46 (1998): 18-36.
19. Lee, Michael. "Molecular Phylogenies become Functional" Trends in Ecology and Evolution. 14
(1999): 177-178.
20. Levinton, Jeffrey S. "The Big Bang of Animal Evolution." Scientific American 267 (1992): 84-91.
21. Lewin, Roger. "Evolutionary Theory Under Fire." Science. 210 (1980): 883.
22. Lowenstein, J. and A. Zihlman. "Unreliable trees." Nature, 355 (1992): 783.
23. Mahoney, Michael. "Publication Prejudices: an Experimental Study of Confirmatory Bias in the Peer
Review System." Cognitive Therapy and Research. 1:2 (1977): 161-175.
24. Margoulis, L., and D. Sagan. "Bacterial Bedfellows." Natural History 96 (1987): 26-33.
25. Martin W., and M. Muller. "The Hydrogen Hypothesis for the First Eukaryote." Nature 392 (1998):
37-41.
26. Mikkola, K. "On the Selective Forces Acting in the Industrial Melanism of Biston oligia Moths."
Biological Journal of the Linnean Society 21 (1984): 409-421.
27. Monastersky, Richard. National Geographic (1998): 58-81.
28. Mynatt, Clifford. "Confirmation Bias in a Simulated Research Environment: An Experimental Study
of Scientific Inference." Quarterly Journal of ExperimentalPsychology. 29 (1977): 85-95.
29. National Academy of Science. Teaching About Evolution and the Nature of Science. Washington:
National Academy Press, 1998.
30. National Academy of Science. National Science Education Standards. Washington, National
Academy Press, 1996.
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Critical Analysis of Evolution – Grade 10
31. Pennisi, E. "Direct descendants from an RNA world." Science 280 (1998): 673.
32. Philippe, Herve, and Patrick Forterre. "The Rooting of the Universal Tree of Life is Not Reliable."
Journal of Molecular Evolution 49 (1999): 509-523.
33. Plous, Scott. The Psychology of Judgment and Decision Making. New York: McGraw Hill, 1993.
34. Richardson, Michael K. "There is no Highly Conserved Stage in the Vertebrates: Implications for
Current Theories of Evolution and Development," Anatomy and Embryology 196 (1997): 91-106.
35. Samarapungavan, Ala. "Children's judgment in theory choice tasks: Scientific rationality in
childhood." Cognition. 45 (1992): 1-32.
36. Shubin, Neil H. and Charles R. Marshall. "Fossils, Genes, and the Origin of Novelty." Deep Time
(2000): 324-340.
37. Smith, John M., and Eörs Szathmáry. The Major Transitions in Evolution. Oxford: Oxford UP, 1995.
38. Smith, Mike U. "Counterpoint: Belief, Understanding, and Teaching of Evolution." Journal of
Research in Science Teaching. 3:5 (1994): 591-597.
39. Sokal, R., and P. Sneath. Principles of Numerical Taxonomy. San Francisco: Freeman, 1963.
40. Thagard, Paul. Mind, Society, and the Growth of Knowledge. Philosophy of Science. (1994): 61.
41. Thomson , Keith S. "Macroevolution: The Morphological Problem," American Zoologist 32 (1992):
106-112.
42. Thomson, Keith S. "The Meanings of Evolution." American Scientist. 70. (1982): 529-531.
43. Towe, Kenneth M. "Environmental Oxygen Conditions During the Origin and Early Evolution of
Life." Advances in Space Research 18 (1996): 7-15.
44. Wells, Jonathan. Icons of Evolution. Washington: Regency Publishing, 2000.
Attachments:
Attachment A, Five Aspects of Evolution
Attachment B, Investigative Worksheet
Attachment C, Critical Analysis Rubric
Attachment D, Critical Analysis Worksheet
16
Critical Analysis of Evolution – Grade 10
Attachment A
Five Aspects of Evolution
Aspect 1: Homology
Citations #8, 9, 15 and 39 in the General Tips Section may provide a starting point for
student research. It is suggested that students employ additional resources in their research.
Brief Supporting Sample Answer: Different animals have very similar
anatomical and genetic structures. This suggests that these animals share a common
ancestor from which they inherited the genes to build these anatomical structures.
Evolutionary biologists call similarities that are due to common ancestry
"homologies." For example, the genes that produce hemoglobin molecules (an
oxygen carrying protein) in chimps and humans are at least 98% identical in
sequence. As another example, bats, humans, horses, porpoises and moles all share a
forelimb that has the same pattern of bone structure and organization. The
hemoglobin molecule and the "pentadactyl limb" provide evidence for common
ancestors. Also, the genetic code is universal, suggesting that a common ancestor is
the source.
More accurately: Similar structures in similar organisms are said to be "homologous" if they are
most easily explained as variations in a structure of a common ancestor. In previous years (e.g.
pre-Darwin), the term "homology" was used differently than it is now, which is confusing to
some, and provides fodder for those who want to attack evolution. To determine whether
organisms share a common ancestor, much more is required than identifying a similar structure.
On morphological grounds, many structures must be similar for two species to be declared
"closely related." At the level of DNA sequence, many nucleotide sequences must be shared.
Thus, the limbs of tetrapods are homologous because many lines of evidence indicate that these
species share common ancestors that had such limbs. The wings of birds are not homologous to
the wings of insects, however, because their common ancestor did not have either tetrapod limbs
(which form bird wings) or arthropod wings.
Brief Challenging Sample Answer: Some scientists think similarities in
anatomical and genetic structure reflect similar functional needs in different animals,
not common ancestry. The nucleotide sequence of hemoglobin DNA is very similar
between chimps and humans, but this may be because they provide the same function
for both animals. Also, if similar anatomical structures really are the result of a shared
evolutionary ancestry, then similar anatomical structures should be produced by
related genes and patterns of embryological development. However, sometimes,
similar anatomical structures in different animals are built from different genes and
by different pathways of embryological development. Scientists can use these
different anatomical structures and genes to build versions of Darwin family trees that
will not match each other. This shows that diverse forms of life may have different
ancestry.
More accurately: Similarities in structures could result from convergent evolution, rather than
from homology. This makes it a challenge to determine just what structures are homologous. Is
there evidence that structures that are thought to be homologous are, in fact, not? To reach this
conclusion requires that examples are found for which current scientific thought infers homology,
but for which it is possible to demonstrate that the species involved do not share a common
ancestor with at least a rudimentary form of that character. Such examples have been found by
evolutionary biologists, resulting in re-examination of the data and the inferences from the data.
Oddly, no such examples have demonstrated that homology does not exist, or that descent with
17
Critical Analysis of Evolution – Grade 10
modification cannot occur. Of course, it is easy to say that a single characteristic (such as
hemoglobin) might be the result of creation or design, but it has proven difficult to apply this
logic to the vast array of characteristics upon which evolutionary relationships are based.
Two additional points:
1. There is no mechanism by which organisms can recognize the "functional needs" and
therefore build hemoglobin molecules (or other molecules or structures) to meet these needs. Nor
is there any reason that, in response to such needs, organisms would build them the same way,
when other solutions to the same problem can also exist. That is, it is possible to ruminate on this
question, but it is hard to develop a model for how it could come about in practice. This is not
challenging data, but challenging speculation.
2. There often are, indeed, similar structures in different species, that derive from different
developmental processes. These are called "analogous" and not "homologous." It is misleading to
use analogy as an argument that homology is incorrect. There may be challenges to determining
what is analogous and what is homologous, but the presence of one does not prove the absence of
the other.
Aspect 2: Fossil Record
Citations #8, 10, 11 and 29 in the General Tips Section may provide a starting point for
student research. It is suggested that students employ additional resources in their research.
Brief Supporting Sample Answer: The fossil record shows an increase in the
complexity of living forms from simple one-celled organisms, to the first simple
plants and animals, to the diverse and complex organisms that live on Earth today.
This pattern suggests that later forms evolved from earlier simple forms over long
periods of geological time. Macroevolution is the large-scale evolution occurring over
geologic time that results in the formation of new taxonomic groups. The slow
transformations are reflected in transitional fossils such as Archaeopteryx (a reptile
like bird) and mammal-like reptiles. These transitional fossils bridge the gap from one
species to another species and from one branch on the tree of life to another.
This answer contains several misconceptions.
1. It assumes that the progress of evolution has been from simple to complex. While it is true
that the complex forms now extant evolved from less complex distant ancestors, there is no
general progression toward complexity. Many evolutionary trends toward less complexity have
been documented.
2. It implies that the increase in complexity is the only evidence from the fossil record that has
been used to develop evolutionary theory. There are many, many more kinds of information that
have been provided by the fossil record, and many more lines of evidence in support of the theory
of common descent.
3. Macroevolution is, again, mis-defined. Nonetheless, the concept is valid that taxonomic
groups have, indeed, diversified. It is erroneous to imply that this requires "slow
transformations," and it is erroneous to state that transitional fossils "bridge the gap" between
species. Often, speciation events exhibit only the former species and the new species, with no
transitional species in between.
4. It is very wrong to suggest that transitional fossils bridge the gap between branches on the tree
of life. This suggests that extant species can interconvert, which they cannot. The "gaps"
between different branches are true biological differences. The transitional fossils are, at best,
examples of animals that were contemporary with the ancestors of the extant animals. They are
not bridges between species, but ancestors of species.
Brief Challenging Sample Answer: Transitional fossils are rare in the fossil
18
Critical Analysis of Evolution – Grade 10
record. A growing number of scientists now question that Archaeopteryx and other
transitional fossils really are transitional forms. The fossil record as a whole shows
that major evolutionary changes took place suddenly over brief periods of time
followed by longer periods of "stasis" during which no significant change in form or
transitional organisms appeared (Punctuated Equilibria). The "Cambrian explosion"
of animal phyla is the best known, but not the only example, of the sudden
appearance of new biological forms in the fossil record.
This answer also includes a number of misconceptions.
1. To say that transitional fossils are rare is partially correct, in the sense that the direct
descendents of a particular species can only be the individual animals or plants in that specific
lineage. There are likely to be many more fossils of sibling species or genera. We have
insufficient data at present to state clearly that any particular fossil is the direct descendent of any
other organism.
2. It is not fully explained here who the scientists are that question the validity of Archaeopteryx
as a transitional fossil, and why they question it. Analysis of the explanations that are available
on the web reveals that the usual explanation is that it displays a mosaic of characteristics, some
reptilian, some birdlike. This reveals the misconception that a "transitional form" must be a
perfect intermediate in all characteristics, in violation of the known mechanism of genetic
inheritance.
3. It is irrelevant to bring in punctuated equilibrium, since it is the best explanation for the pattern
of diversity that is seen in the fossil record. That is has been raised reveals the misconception that
evolution should, for some reason, be true only if it happens with perfectly linear kinetics, with
every individual changing form at exactly the same rate.
4. The term "Cambrian Explosion" is commonly misinterpreted to mean that all of the phyla
appeared suddenly from nowhere. In fact, careful analysis of the fossil record, particularly the
Ediacaran assemblage that shows a great diversity of soft-bodied forms, and demonstrates that
many species existed well before the Cambrian. The "explosion" apparently took place over at
least 15 million years, and possibly 45 million, hardly an eye-blink. The novelty of the Cambrian
explosion appears to be little more than the development of shells--hard body parts that are more
easily fossilized than the soft tissues prevalent before (and remarkably preserved in the Ediacaran
hills).
5. In sum, this "challenging answer" not only suffers from a number of misconceptions, but it
also fails to explain why any of the things that it lists might be challenges to the validity of the
fossil record. The data concerning them are not challenges at all.
Aspect 3: Antibiotic Resistance
Citations in the General Tips Section may provide a starting point for student research. It is
suggested that students employ additional resources in their research.
Brief Supporting Sample Answer: The number of strains of antibiotic
resistant bacteria, such as of Staphylococcus aureus, have significantly increased in
number over time. Antibiotics used by patients to eliminate disease-causing bacterial
organisms have facilitated this change. When some bacteria acquire a mutation that
allows them to survive in the presence of antibiotics, they begin to survive in greater
numbers than those that do not have this mutation-induced resistance. This shows
how environmental changes and natural selection can produce significant changes in
populations and species over time.
This is reasonable, but should mention agricultural use of antibiotics, which is far more serious
than medical use, inasmuch as it is more widespread. It should also state that the resistant
bacteria "grow in the presence of the antibiotic" rather than "begin to survive" in greater numbers.
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Critical Analysis of Evolution – Grade 10
Brief Challenging Sample Answer: The increase in the number of antibiotic
resistant bacterial strains demonstrates the power of natural selection to produce small
but limited changes in populations and species. It does not demonstrate the ability of
natural selection to produce new forms of life. Although new strains of
Staphylococcus aureus have evolved, the speciation of bacteria (prokaryotes) has not
been observed, and neither has the evolution of bacteria into more complex
eukaryotes. Thus, the phenomenon of antibiotic resistance demonstrates
microevolution.
This "challenging" answer illustrates the author's misconception that microevolution and
macroevolution are fundamentally different. Indeed, the author states that "new strains…have
evolved." This seems to negate this argument as a challenge to evolution.
The fact that "no one has observed" macroevolution, and that the fact of the evolution of
antibiotic-resistant bacteria is "only" variation within a single "kind" of bacteria is not an
argument against macroevolution. It merely states that this experiment did not happen to show
the evolution of a new species. This is not proof that new species cannot evolve.
Rather, this "challenging" answer indicates quite nicely that the author accepts antibiotic
resistance as an example of evolution, specifically the aspect referred to as microevolution. There
is no claim by evolutionary biologists that it proves anything more. In short, it may be necessary
to conclude that there does not appear to be challenging information in the evolution of
antibiotic-resistant bacteria.
Aspect 4: Peppered Moths (Biston betularia)
Citations #5, 26 and 44 in the General Tips Section may provide a starting point for student
research. It is suggested that students employ additional resources in their research.
Brief Supporting Sample Answer: During the industrial revolution in
England, more soot was released into the air. As a result, the tree trunks in the
woodlands grew darker in color. This environmental change also produced a change
in the population of English peppered moths (scientifically known as
Biston betularia). Studies during the 1950s have suggested a reason for this change.
It was observed that light-colored moths resting on dark-colored tree trunks were
readily eaten by birds. They had become more visible by their predators compared to
their dark-colored counterparts. This different exposure to predation explained why
the light-colored moths died with greater frequency when pollution darkened the
forest. It also explained why light-colored moths later made a "comeback" when air
quality improved in England. This whole situation demonstrates how the process of
natural selection can change the features of a population over time.
This is reasonable. It states that the peppered moth observations prove the principle of natural
selection.
Brief Challenging Sample Answer: English peppered moths show that
environmental changes can produce microevolutionary changes within a population.
They do not show that natural selection can produce major new features or forms of
life, or a new species for that matter--i.e., macroevolutionary changes. From the
beginning of the industrial revolution, English peppered moths came in both light and
dark varieties. After the pollution decreased, dark and light varieties still existed. All
that changed during this time was the relative proportion of the two traits within the
population. No new features and no new species emerged. In addition, recent
scientific articles have questioned the factual basis of the study performed during the
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Critical Analysis of Evolution – Grade 10
1950s. Scientists have learned that peppered moths do not actually rest on tree trunks.
This has raised questions about whether color changes in the moth population were
actually caused by differences in exposure to predatory birds.
Again, failure to demonstrate speciation in one series of observations does not prove that
speciation does not occur. Indeed, speciation has been observed in many other instances. Again,
this "challenging answer" shows that the author accepts the power of natural selection to change
gene frequencies--which is essentially the definition of evolution.
The latter parts of this "answer," that "peppered moths do not actually rest on tree
trunks," is false, and should earn this answer a poor grade. Peppered moths have been observed
alighting on trunks at least 25% of the time. At other times, they alighted on trunks near
branches, or on branches--which, like trunks, are subject to darkening when soot is present. This
is a distraction, and not a valid issue.
In short, there does not appear to be challenging information here--only an effort by the
author (or the sources from which the author obtained the information) to mis-direct the reader's
attention away from the data, and an effort to pretend that microevolution is not evolution.
Aspect 5: Endosymbiosis (formation of cellular organelles)
Citations #24, 25, 31 in the General Tips Section may provide a starting point for student
research. It is suggested that students employ additional resources in their research.
Brief Supporting Sample Answer: Complex eukaryotic cells contain
organelles such as chloroplasts and mitochondria. These organelles have their own
DNA. This suggests that bacterial cells may have become established in cells that
were ancestral to eukaryotes. These smaller cells existed for a time in a symbiotic
relationship within the larger cell. Later, the smaller cell evolved into separate
organelles within the eukaryotic ancestors. The separate organelles, chloroplast and
mitochondria, within modern eukaryotes stand as evidence of this evolutionary
change.
This is adequate, but incomplete. It is not the presence of DNA that indicates that these
organelles are derived from prokaryotic ancestors (although this does provide a suggestion that
this might be so). Rather, it is the DNA sequences of mitochondrial and chloroplast DNA that
demonstrates that they are prokaryotic. Furthermore,the translational machinery in these
organelles has prokaryotic features, not eukaryotic. That is, the DNA sequence data indicate that
these organelles are closely allied with bacteria. Although direct testing has not shown that one
bacterial species can engulf another, but fail to digest it, and over the next billion years reduce it
to an organelle, the fossil data and the biochemical data are entirely consistent with this
hypothesis, which remains the current best explanation of their origin.
Brief Challenging Sample Answer: Laboratory tests have not yet
demonstrated that small bacteria (prokaryotic cells) can change into separate
organelles, such as mitochondria and chloroplasts within larger bacterial cells. When
smaller bacterial cells (prokaryotes) are absorbed by larger bacterial cells, they are
usually destroyed by digestion. Although some bacterial cells (prokaryotes) can
occasionally live in eukaryotes, scientists have not observed these cells changing into
organelles such as mitochondria or chloroplasts.
The failure to reconstruct in the laboratory an event that fossil evidence indicates occurred over
the course of hundreds of millions of years is simply not evidence that the event did not occur. It
is therefore necessary to rephrase this answer to say that "some people state that reconstruction of
every evolutionary step is required before they will accept it." However, many of the individual
aspects of this theory have been shown, such as aborted digestion of bacterial cells that have been
21
Critical Analysis of Evolution – Grade 10
taken up by endocytosis, and even the development of a lifestyle as an intracellular parasite.
Thus, some of the steps have been observed, so the concept is reasonable not only on the basis of
the other lines of evidence supporting it, but even with respect to verifying the likelihood of at
least some of the essential steps.
Again, this does not appear to be a valid challenge to evolutionary theory.
The remaining portions of the Critical Analysis lesson plan are data-collection sheets and scoring
rubrics, which are not evaluated here. They could be useful in terms of helping students maintain a
logical thought process as they proceed through this analysis.
The main issue is that the "informational web sites" supplied to the teachers and students by the
authors of the lesson plan are either difficult-to-follow scientific sites or journal libraries, or easyto-follow religious anti-evolution sites.
[The references supplied by the lesson plan have not been evaluated.]
22