Debunking Misconceptions Regarding the Theory of Evolution

Transcription

1 Debunking Misconceptions Regarding the Theory of Evolution Myth 1 - Evolution has never been observed. Biologists define evolution as a change in the gene pool of a population over time. One example is insects developing a resistance to pesticides over the period of a few years. Most people will not disagree with this fact. Direct observations do show us that species change over time, and DNA itself is changeable. Genes change by mutation and can produce variations among species, like a white tiger or bacteria that are resistant 1 to antibiotics. At this level, most people do not disagree with the theory of evolution because it can be directly observed. With advances in gene sequences it has become easier to gather data on how a population changes. Biologists can compare one group of frogs to another group of frogs and see that their DNA sequences have differences (and similarities). Even human DNA can be used to trace a family lineage because ethnic groups have different genetic markers. "Who Do You Think You Are" is a tv show that attempts to find relationships between living celebrities and historical figures of the past using DNA. This would not be possible if modern humans did not have measurable differences in their DNA based on where they originated from. Myth 2 - Evolution violates the 2nd law of thermodynamics. The Second Law of Thermodynamics is commonly known as the Law of Increased Entropy. As useable energy in a system is converted to unusable heat energy, entropy increases. Entropy is a measure of disorganization, randomness and chaos. What does this have to do with evolution? Some people interpret the second law to mean that order cannot come from disorder, as it is the natural tendency 2 within a system to become more disorderly and more chaotic. This shows more a misconception about thermodynamics than about evolution. Life is not a closed system, organisms must constantly take in energy to maintain their homeostasis, a form of internal order. Plants get energy from the sun, animals get energy from eating plants, and so forth. Without this addition of energy, the organism will die. Evolution does not violate this law because there is a source of energy for all life on this planet, the sun. It is also erroneous 3 to think that order can never come from disorder, as many things naturally organize. Water molecules stick together with hydrogen bonds causing surface tension. Snowflakes and crystals form, and even with the right combination of raw materials, DNA will

2 form within a solution, all of these things can be explained with chemistry and do not violate any physical laws. Myth 3 - There are no transitional fossils. What about the Missing Link? A transitional fossil is one that looks like an intermediate between two lineages, it may contain features of both groups or a feature shared amongst two groups of seemingly unrelated organisms. This myth makes the assumption that evolution occurs in a linear 4 fashion, with each animal moving step by step toward its current form. Unfortunately, many images of evolution tend to reinforce the idea of linear evolution. There is nothing in the theory that says organisms evolve this way. In fact, Darwin described his model as tree, with groups of animals occupying a branch, where some branches are closer than others. Think of the Felis order, where there are many groups of cats such as tigers, lions, and jaguars, they share a common ancestor. A lion is not going to turn into a jaguar, you won't find a link between these two animals. There are plenty of transitional fossils in the record. The absence of any one intermediate does not negate the whole theory. Paleontologists must work with fossils they can find, and it is not surprising that we would have some gaps in our record. Think of a jigsaw puzzle that has a couple of missing pieces, you can still get an idea of what the picture is. There are also some groups that are well represented in the fossil record and provide us a clear picture of how a group has changed over time. Some notable 5 examples are the transitions from reptile to mammal, from land animal to early whale, and from dinosaur to bird. You can view several examples of transitional fossils in paleontology records. Whale Fossils Horse Fossils Bird Fossils Hominid Fossils Myth 4 - Evolution says that life originated, and evolution proceeds, by random chance. There is probably no other statement which is a better indication that the arguer doesn't understand evolution. Chance certainly plays a large part in evolution, but this argument completely ignores the role of natural selection. Chance provides genetic variation, which is the raw material that natural selection has to work with. From there, natural selection sorts out variations that give greater success. Atoms and molecules do not arrange themselves randomly either, but according to their chemical properties: sodium naturally bonds to chloride to form salt, carbon will naturally form long chains. Also realize that evolution does not necessarily deal with how life first began, evolution focuses on the processes that continue to guide and change existing life.

3 A common analogy 6 related to this misconception is the one of the monkey and the typewriter. Those who do not understand evolution argue that if you sit a monkey at a typewriter and let it randomly hit keys, it will never produce a novel. This analogy leaves out the essential component 7 of evolution - SELECTION. The analogy would have to take into account that the monkey at the typewriter would stop occasionally and weed out bad designs, such as combinations of letters that do not make words. Once you have a collection of words, eliminate any words that do not make sense..and so forth. If you continued this way, you may eventually develop a sentence or a paragraph, or even a novel if you continued long enough. Evolution works on the principle that random chance plays a role, but selection of good traits is more important to the overall process. Myth 5 - Evolution is only a theory; it hasn't been proved First, we should clarify 8 what "evolution" means. Like so many other words, it has more than one meaning. Its strict biological definition is change in genes over time which lead to a change in traits, something that is observable. People often associate the word "evolution" with common descent, which suggest that organisms share a common ancestor. To gather evidence for common descent, inferences 9 must be made about current organisms and their relationship to other organisms, both past and present. Biologists may disagree on these lineages and relationships, but that does not mean they disagree with the theory of evolution. Calling the theory of evolution "only a theory" is, strictly speaking, true, but the idea it tries to convey 10 is completely wrong. The argument rests on a confusion between what "theory" means in common language and what it means in science. In science a theory is a model that is used to explain sets of data, and can be used to make predictions. Theories in science can be modified or even proven false if new data is discovered. Theories are supported by a wide variety of evidence from scientists from different fields and can be used to provide scientists a way to understand natural processes.

4 Name: Date: 1. What is the main point of the article? a. explain common misconceptions of evolution b. disprove evolution by pointing out problems with the theory c. compare the theory of evolution to other ideas about the origins of life 2. Why does the theory of evolution NOT violate the Law of Thermodynamics? (Circle the section where you found the answer) a. all living things produce heat b. living things eventually fall into chaos c. the earth is not a closed system, life forms must consume energy 3. A fossil is discovered that has both lizard and bird features. This would be referred to as a(n): (Place an arrow at the section where you found the answer) a. target fossil b. transitional fossil c. genetic marker 4. How can evolution be directly observed? (Place an X next to this section) a. arranging fossils in a specific pattern to show change over time b. collecting data on DNA sequences of past and present organisms c. observing changes in species that have a short life cycle, such as a cockroach 5. A scientific theory is one that: (Place a checkmart next to this section) a. can be modified if new evidence presents itself b. cannot ever be disproven c. is just a guess or an idea 6. In the article, several words are underlined. Use the context of the article to determine the meaning of those words, list them below by their number with a short definition or description. You may use a dictionary, but it is not necessary if you can determine the meaning from the text. 1. = 2. = 3. = 4. = 5. = 6. = 7. = 8. = 9. = 10. =

5 7. Examine the article, how does the author organize the text. a. by separating main points with pictures that illustrate the points b. by using bold heading text to separate the main points c. by writing conclusions and transitions that clearly indicate that a section has ended 8. If the article were to continue, what might be the next section you would see? a. a section that says "Myth 6" b. a chart or a graph showing evidence of evolution c. a section on alternative theories of evolution 9. Based on the text, what can you infer about the author? a. the author is someone who wants to disprove evolution b. the author is a biologist who wants to explain evolution c. the author is someone who does not understand the theory Develop a question you would like to ask this author based on your own understanding of evolution.