Although the theory of evolution initially generated some controversy, by 20 years after the publication of On the Origin of Species it was almost universally accepted by biologists, particularly younger biologists. Nevertheless, the theory of evolution is a difficult concept and misconceptions about how it works abound. In addition, there are those that reject it as an explanation for the diversity of life.
CONCEPT IN ACTION
This website addresses some of the main misconceptions associated with the theory of evolution.
Evolution Is Just a Theory
Critics of the theory of evolution dismiss its importance by purposefully confounding the everyday usage of the word “theory” with the way scientists use the word. In science, a “theory” is understood to be a concept that has been extensively tested and supported over time. We have a theory of the atom, a theory of gravity, and the theory of relativity, each of which describes what scientists understand to be facts about the world. In the same way, the theory of evolution describes facts about the living world. As such, a theory in science has survived significant efforts to discredit it by scientists, who are naturally skeptical. While theories can sometimes be overturned or revised, this does not lessen their weight but simply reflects the constantly evolving state of scientific knowledge. In contrast, a “theory” in common vernacular means a guess or suggested explanation for something. This meaning is more akin to the concept of a “hypothesis” used by scientists, which is a tentative explanation for something that is proposed to either be supported or disproved. When critics of evolution say evolution is “just a theory,” they are implying that there is little evidence supporting it and that it is still in the process of being rigorously tested. This is a mischaracterization. If this were the case, geneticist Theodosius Dobzhansky would not have said that “nothing in biology makes sense, except in the light of evolution.”1
An individual is born with the genes it has—these do not change as the individual ages. Therefore, an individual cannot evolve or adapt through natural selection. Evolution is the change in genetic composition of a population over time, specifically over generations, resulting from differential reproduction of individuals with certain alleles. Individuals do change over their lifetime, but this is called development; it involves changes programmed by the set of genes the individual acquired at birth in coordination with the individual’s environment. When thinking about the evolution of a characteristic, it is probably best to think about the change of the average value of the characteristic in the population over time. For example, when natural selection leads to bill-size change in medium ground finches in the Galápagos, this does not mean that individual bills on the finches are changing. If one measures the average bill size among all individuals in the population at one time, and then measures the average bill size in the population several years later after there has been a strong selective pressure, this average value may be different as a result of evolution. Although some individuals may survive from the first time to the second, those individuals will still have the same bill size. However, there may be enough new individuals with different bill sizes to change the average bill size.
Evolution Explains the Origin of Life
It is a common misunderstanding that evolution includes an explanation of life’s origins. Conversely, some of the theory’s critics complain that it cannot explain the origin of life. The theory does not try to explain the origin of life. The theory of evolution explains how populations change over time and how life diversifies—the origin of species. It does not shed light on the beginnings of life including the origins of the first cells, which is how life is defined. The mechanisms of the origin of life on Earth are a particularly difficult problem because it occurred a very long time ago, over a very long time, and presumably just occurred once. Importantly, biologists believe that the presence of life on Earth precludes the possibility that the events that led to life on Earth can be repeated because the intermediate stages would immediately become food for existing living things. The early stages of life included the formation of organic molecules such as carbohydrates, amino acids, or nucleotides. If these were formed from inorganic precursors today, they would simply be broken down by living things. The early stages of life also probably included more complex aggregations of molecules into enclosed structures with an internal environment, a boundary layer of some form, and the external environment. Such structures, if they were formed now, would be quickly consumed or broken down by living organisms.
However, once a mechanism of inheritance was in place in the form of a molecule like DNA or RNA, either within a cell or within a pre-cell, these entities would be subject to the principle of natural selection. More effective reproducers would increase in frequency at the expense of inefficient reproducers. So while evolution does not explain the origin of life, it may have something to say about some of the processes operating once pre-living entities acquired certain properties.
Organisms Evolve on Purpose
Statements such as “organisms evolve in response to a change in an environment,” are quite common. There are two easy misunderstandings possible with such a statement. First of all, the statement must not be understood to mean that individual organisms evolve, as was discussed above. The statement is shorthand for “a population evolves in response to a changing environment.” However, a second misunderstanding may arise by interpreting the statement to mean that the evolution is somehow intentional. A changed environment results in some individuals in the population, those with particular phenotypes, benefiting and, therefore, producing proportionately more offspring than other phenotypes. This results in change in the population if the characters are genetically determined.
It is also important to understand that the variation that natural selection works on is already in a population and does not arise in response to an environmental change. For example, applying antibiotics to a population of bacteria will, over time, select for a population of bacteria that are resistant to antibiotics. The resistance, which is caused by a gene, did not arise by mutation because of the application of the antibiotic. The gene for resistance was already present in the gene pool of the bacteria, likely at a low frequency. The antibiotic, which kills the bacterial cells without the resistance gene, strongly selects for individuals that are resistant, since these would be the only ones that survived and divided. Experiments have demonstrated that mutations for antibiotic resistance do not arise as a result of antibiotic application.
In a larger sense, evolution is also not goal directed. Species do not become “better” over time; they simply track their changing environment with adaptations that maximize their reproduction in a particular environment at a particular time. Evolution has no goal of making faster, bigger, more complex, or even smarter species. This kind of language is common in popular literature. Certain organisms, ourselves included, are described as the “pinnacle” of evolution, or “perfected” by evolution. What characteristics evolve in a species are a function of the variation present and the environment, both of which are constantly changing in a non-directional way. What trait is fit in one environment at one time may well be fatal at some point in the future. This holds equally well for a species of insect as it does the human species.
Evolution Is Controversial among Scientists
The theory of evolution was controversial when it was first proposed in 1859, yet within 20 years virtually every working biologist had accepted evolution as the explanation for the diversity of life. The rate of acceptance was extraordinarily rapid, partly because Darwin had amassed an impressive body of evidence. The early controversies involved both scientific arguments against the theory and the arguments of religious leaders. It was the arguments of the biologists that were resolved after a short time, while the arguments of religious leaders have persisted to this day.
The theory of evolution replaced the predominant theory at the time that species had all been specially created within relatively recent history. Despite the prevalence of this theory, it was becoming increasingly clear to naturalists during the nineteenth century that it could no longer explain many observations of geology and the living world. The persuasiveness of the theory of evolution to these naturalists lay in its ability to explain these phenomena, and it continues to hold extraordinary explanatory power to this day. Its continued rejection by some religious leaders results from its replacement of special creation, a tenet of their religious belief. These leaders cannot accept the replacement of special creation by a mechanistic process that excludes the actions of a deity as an explanation for the diversity of life including the origins of the human species. It should be noted, however, that most of the major denominations in the United States have statements supporting the acceptance of evidence for evolution as compatible with their theologies.
The nature of the arguments against evolution by religious leaders has evolved over time. One current argument is that the theory is still controversial among biologists. This claim is simply not true. The number of working scientists who reject the theory of evolution, or question its validity and say so, is small. A Pew Research poll in 2009 found that 97 percent of the 2500 scientists polled believe species evolve.2 The support for the theory is reflected in signed statements from many scientific societies such as the American Association for the Advancement of Science, which includes working scientists as members. Many of the scientists that reject or question the theory of evolution are non-biologists, such as engineers, physicians, and chemists. There are no experimental results or research programs that contradict the theory. There are no papers published in peer-reviewed scientific journals that appear to refute the theory. The latter observation might be considered a consequence of suppression of dissent, but it must be remembered that scientists are skeptics and that there is a long history of published reports that challenged scientific orthodoxy in unpopular ways. Examples include the endosymbiotic theory of eukaryotic origins, the theory of group selection, the microbial cause of stomach ulcers, the asteroid-impact theory of the Cretaceous extinction, and the theory of plate tectonics. Research with evidence and ideas with scientific merit are considered by the scientific community. Research that does not meet these standards is rejected.
Other Theories Should Be Taught
A common argument from some religious leaders is that alternative theories to evolution should be taught in public schools. Critics of evolution use this strategy to create uncertainty about the validity of the theory without offering actual evidence. In fact, there are no viable alternative scientific theories to evolution. The last such theory, proposed by Lamarck in the nineteenth century, was replaced by the theory of natural selection. A single exception was a research program in the Soviet Union based on Lamarck’s theory during the early twentieth century that set that country’s agricultural research back decades. Special creation is not a viable alternative scientific theory because it is not a scientific theory, since it relies on an untestable explanation. Intelligent design, despite the claims of its proponents, is also not a scientific explanation. This is because intelligent design posits the existence of an unknown designer of living organisms and their systems. Whether the designer is unknown or supernatural, it is a cause that cannot be measured; therefore, it is not a scientific explanation. There are two reasons not to teach nonscientific theories. First, these explanations for the diversity of life lack scientific usefulness because they do not, and cannot, give rise to research programs that promote our understanding of the natural world. Experiments cannot test non-material explanations for natural phenomena. For this reason, teaching these explanations as science in public schools is not in the public interest. Second, in the United States, it is illegal to teach them as science because the U.S. Supreme Court and lower courts have ruled that the teaching of religious belief, such as special creation or intelligent design, violates the establishment clause of the First Amendment of the U.S. Constitution, which prohibits government sponsorship of a particular religion.
The theory of evolution and science in general is, by definition, silent on the existence or non-existence of the spiritual world. Science is only able to study and know the material world. Individual biologists have sometimes been vocal atheists, but it is equally true that there are many deeply religious biologists. Nothing in biology precludes the existence of a god, indeed biology as a science has nothing to say about it. The individual biologist is free to reconcile her or his personal and scientific knowledge as they see fit. The Voices for Evolution project (http://ncse.com/voices), developed through the National Center for Science Education, works to gather the diversity of perspectives on evolution to advocate it being taught in public schools.
The theory of evolution is a difficult concept and misconceptions abound. The factual nature of evolution is often challenged by wrongly associating the scientific meaning of a theory with the vernacular meaning. Evolution is sometimes mistakenly interpreted to mean that individuals evolve, when in fact only populations can evolve as their gene frequencies change over time. Evolution is often assumed to explain the origin of life, which it does not speak to. It is often spoken in goal-directed terms by which organisms change through intention, and selection operates on mutations present in a population that have not arisen in response to a particular environmental stress. Evolution is often characterized as being controversial among scientists; however, it is accepted by the vast majority of working scientists. Critics of evolution often argue that alternative theories to evolution should be taught in public schools; however, there are no viable alternative scientific theories to evolution. The alternative religious beliefs should not be taught as science because it cannot be proven, and in the United States it is unconstitutional. Science is silent on the question of the existence of a god while scientists are able to reconcile religious belief and scientific knowledge.
The word “theory” in theory of evolution is best replaced by ________.
D. alternate explanation
Why are alternative scientific theories to evolution not taught in public school?
A. more theories would confuse students
B. there are no viable scientific alternatives
C. it is against the law
D. alternative scientific theories are suppressed by the science establishment
How does the scientific meaning of “theory” differ from the common, everyday meaning of the word?
In science, a theory is a thoroughly tested and verified set of explanations for a body of observations of nature. It is the strongest form of knowledge in science. In contrast, a theory in common usage can mean a guess or speculation about something, meaning that the knowledge implied by the theory may be very weak.
Explain why the statement that a monkey is more evolved than a mouse is incorrect.
The statement implies that there is a goal to evolution and that the monkey represents greater progress to that goal than the mouse. Both species are likely to be well adapted to their particular environment, which is the outcome of natural selection.
- 1 Theodosius Dobzhansky. “Biology, Molecular and Organismic.” American Zoologist 4, no. 4 (1964): 449.
- 2 Pew Research Center for the People & the Press, Public Praises Science; Scientists Fault Public, Media (Washington, DC, 2009), 37.Contributors
Cell membrane vs cell wall. First off, you must be able to distinguish between a cell membrane and a cell wall. All cells have a cell membrane. This membrane separates the contents inside the cell from anything outside the cell. On any cell diagram, cell membrane will be the inner line. If the cell diagram has an outer line, this is the cell wall, and it must be a plant, bacterial or fungal cell.
The nucleus. Another pitfall is to call the nucleus the ‘brain of the cell’. Don’t write that in the exam! The nucleus is not a squidgy pink folded organ and examiners just will not accept that response! The nucleus controls the cell because it contains the genetic code to make the cell’s proteins.
Mitochondria. Mitochondria release or transfer energy in the cell. Remember that energy cannot be created (or destroyed) so mitochondria do not “create” energy.
Enzymes. Enzymes are large molecules that are found inside cells. But enzymes themselves are not alive! So they can’t die, they can only be denatured when the shape of the enzyme molecule changes and this distorts their active site.
Division vs differentiation. Finally remember that cell division means cells splitting in half, while differentiation is when different genes get expressed to specialise the cell for a certain job.
10 Misconceptions about Evolution
One of the difficulties people have with coming to accept the science of evolution is that they have absorbed incorrect or only partially correct information. I’ve kept a list of the mischaracterizations I’ve come across, and I present ten of them here in no particular order.
- Evolution claims that we evolved from monkeys.
No it doesn’t. It doesn’t even claim we evolved from chimpanzees! Rather, evolution predicts that all life on the planet is related. That is to say that if you go back enough generations, you’ll come to a common ancestor for any two life forms. For humans and chimpanzees, the best evidence strongly suggests that the line leading to humans diverged from the line leading to chimpanzees six or seven million years ago. That original population was neither human nor chimpanzee.
- If we evolved from monkeys, why are there still monkeys around?
Start with the same correction as given in #1—apes are closer relatives than monkeys. And then there is a similar misconception. The theory of evolution does not say that currently existing species came from other currently existing species. The most recent common ancestors between humans and Old World monkeys (those from Africa and Asia) were about 25 million years ago (the New World monkeys in South and Central America split off earlier).
- The 2nd Law of Thermodynamics disproves evolution
The reasoning here seems to be that the 2nd Law of Thermodynamics says that disorder (a.k.a. entropy) increases over time. So evolution cannot be correct, since it claims that there is increasing complexity over time. For example, buildings if they are left to themselves become dilapidated over time, rather than remodelling themselves into something better (increasing in order and complexity). But of course the key here is “if they are left to themselves.” The 2nd Law of Thermodynamics applies to closed systems in which there is no external source of energy. But the earth is not a closed system! There is massive energy being poured into the system constantly from the sun. The sun’s energy is converted through natural processes into other forms of energy and powers the development of life on earth. If you include the sun within our system, then yes, things are running down. But we’ve got a few billion years left before the usable energy from the sun is gone.
Yes it can. Any reasonable definition of “new information” in this context has to mean something like “instructions to build something useful that weren’t there before.” That happens a lot through genetic mutations and gene duplication. Here’s a short YouTube video that explains how.
- Evolution is a theory in crisis
No it’s not. Of course scientists debate and argue about the specifics—that’s how science works. But the general framework of evolution including the common descent of all species is overwhelmingly supported by scientists. 98% of the members of AAAS (and 99% of research scientists) accept human evolution (see study). Some of the confusion on this point is that the term “Neo-Darwinism” is often used to mean the specific proposal that there is nothing more to evolution than random genetic mutations and natural selection. There is a lot of debate and dissension among scientists about that point. But it is completely illegitimate to go from “There is vigorous debate about Neo-Darwinism” to the conclusion, “Therefore evolution is a theory in crisis.” That is only rhetoric. [Editor’s note: For more on this, go to our new Common Questions page on the subject.]
- There are no transitional fossils
Well, that depends on what you mean by that. My ancestors are mostly from Germany, but if you went to a cemetery there from several hundred years ago (even in the hometown of my 8th-great grandparents), it would be pretty remarkable if you picked out one tombstone at random and hit upon a direct ancestor of mine. Many of those “fossils” could be fairly close relatives of mine (much closer than those found in Japan), but they represent different lineages that did not lead to me. The same goes for fossils of the ancestors of a species. When we find a specimen that appears to have “transitional” characteristics between two species, like a whale-ish creature with tiny legs, it would be rare if that organism itself led directly to modern whales. But when it is found in the right place and right time period, it is undoubtedly closely related to the truly transitional organism. We might better call these “intermediate” fossils. And there are gobs of these in the fossil record. Together, they make an impressive picture of the transition that occurred between species.
- Evolution is merely “Historical Science” and therefore can’t be tested or confirmed
This is so widely proclaimed, and it perpetuates massive misunderstanding about science. There are lots of different “sciences”, and lots of ink has been spilled attempting to give a precise definition of what it is to be science (often called the demarcation problem). And there is no one sanctioning body who has the authority to determine what counts as real science and what doesn’t. Evolution begins with careful observations (e.g., I found this bone in this layer of rock) then hypotheses are offered for why those specific observations were made (e.g., the bone belonged to a species that lived 65 million years ago) as the hypotheses are developed, they give rise to predictions of other observations (e.g., we should be able to find similar bones in these other layers of rock) and the hypotheses are tested by making those new observations. When the new observations turn out as predicted, they count as confirming evidence (not absolute proof–that doesn’t happen much in any science) when the observations are different than expected, we have to rethink our hypotheses. That kind of process is as scientific as you get. The new science of genetics shows even more clearly how the theory of evolution is tested and confirmed.
- Evolution is man’s word, Creationism is God’s word
First, it should be noted that there are lots of women working on evolution too! Then, if the claim is that Young Earth Creationism (or Old Earth Creationism or Evolutionary Creationism, for that matter) is God’s Word, that is dangerously close to blasphemy. These theories of origins are put together by people. All of them attempt to interpret the Bible responsibly. None of them were handed down from Heaven. If the claim instead is that Young Earth Creationism is taken directly from a plain reading of God’s Word, see the next misconception.
- The plain reading of Scripture clearly supports six day Creationism
If “plain reading” means “what the words clearly mean in my language and culture”, then I suppose Exodus 20:11 could be used to support six day Creationism. But if that is really how we’re supposed to read Scripture, then 1 Samuel 2:8 means the earth is set on pillars, and Deuteronomy 21:21 means we should stone our rebellious sons, and John 15:5 means Jesus is a plant, and Roman 16:16 means we should kiss everyone we meet. The “plain reading” of Scripture leads to picking and choosing which verses we like and which we ignore. That is not a responsible way to read the Bible. There are reasons we don’t take the plain meaning of those other verses as the best interpretation of Scripture that makes us at least ask whether there might be reasons not to take Exodus 20:11 and Genesis 1 in their plain sense.
- Christian scholars accept the Evolutionary Creation position out of the desire for professional advancement
The thinking here is that they want to hold on to their Christian faith, but accept evolution in order to be accepted by their professional peers. I’d be interested in seeing any actual data that supports this claim. I can produce a lot of data that refutes it. Christian scholars typically work at secular universities or Christian colleges. For those at secular universities, to admit they hold to Evolutionary Creation can call their scientific credentials into question. And for those at Christian colleges, showing any sign of being open to the evidence for evolution is not the ticket to career advancement. Believe me, I know this one personally. I don’t know anyone who has accepted Evolutionary Creation for reasons other than being persuaded by the evidence.
Notes & References
This post was originally published on September 28, 2015.
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3.5: Common Misconceptions about Evolution - Biology
Evolution is the single most important concept in all of biology. It is absolutely vital for understanding both the history of life on earth and why our modern organisms have their current traits and behaviors. Nevertheless, it is also one of the most misunderstood concepts in modern science. Much of the confusion stems from creationists’ faulty arguments, but even those who accept evolution often don’t really understand it. Therefore, I am going to describe and debunk ten of the most common myths and misconceptions about evolution.
Myth 1: Evolution is just a theory
This is arguably the most common myth about evolution, and it is probably creationists’ most well worn trope. It is also a fundamental misunderstanding of how science works. I’ve explained this in more detail before, but briefly, evolution is both fact and theory depending on exactly what we are talking about. The idea that all modern organisms (including humans) evolved from a single celled organism over a period of millions of years is a scientific fact. It has been confirmed by the fossil record, genetics, biogeography, etc. Like it or not, it’s a fact, but there is also a theory component. You see, theories explain facts. So, the theory of evolution by natural selection states that natural selection has been the dominant mechanism causing species to evolve. In other words, it is a fact the evolution occurred, and the theory of evolution by natural selection explains how that evolution occurred. Indeed, it is a common misconception that Charles Darwin came up with the idea of evolution. In reality, many scientists before him thought that organisms evolved, but they couldn’t figure out how or why they evolved. So, what Darwin (along with Alfred Russel Wallace) did that was so extraordinary, was to provide a mechanism that drove evolutionary change (i.e., natural selection).
Finally, it is worth noting that theories are actually among our highest forms of scientific certainty. They have been rigorously tested and consistently make accurate predictions. So gravity (i.e., the theory of universal gravity), the idea that all matter is made of atoms (i.e., atomic theory), the idea that all living things are made of cells (i.e., cell theory), the idea that bacteria make you sick (i.e., the germ theory of disease), etc. are all “just theories.”
Myth 2: We evolved from monkeys/apes
We did not evolve from modern apes, but we share a common ancestor with them. In other words, if we back the clock up a few million years, we will find an ape-like ancestor whose populations split, and different groups went down different evolutionary paths. One group evolved into us, and another group evolved into chimps. So we and chimps share a great, great, great…great grandparent who went extinct a few million years ago, but we did not evolve from chimps, monkeys, or modern apes.
Myth 3: Evolution conflicts with the second law of thermodynamics
People often describe the second law of thermodynamics as, “the disorder of a system always increases,” which leads people to erroneously claim that evolution violates the second law because it says that overtime life becomes more organized. The problem is that the above definition is a terrible one which misrepresents the law and overlooks several key components.
The best way to understand the second law is in conjunction with the first law. The first law (also known as the law of the conservation of energy) states that energy cannot be created or destroyed, but it can change forms (e.g., it can go from potential energy to kinetic energy). The second law then describes the natural flow of energy within a system (i.e., the direction in which the changes take place). Both of these are dealing with energy states, and taken together, they say that a system cannot go from a low energy state to a high energy state without the input of additional energy. The classic example of this is a diving board. Someone standing on a tall diving board is in a higher energy state (i.e., they have more potential energy) than someone standing at the bottom of the ladder. So, to a physicist, the person at the bottom is more “disorganized” than the person at the top, because the person at the top has more potential energy. In technical terms, this concept of disorganization is known as entropy, and the person at the top of the board would have less entropy than the person at the bottom.
Notice, these laws do not state that it is impossible for systems to go from a low energy state to a high energy state. Rather, they say that the transition cannot take place without the input of additional energy. In other words, it is completely possible for the person at the bottom of the ladder to climb up onto the board and reach a higher energy state (i.e., become more organized/have less entropy), but doing so requires an input of energy (i.e., they have to use energy to move their muscles and climb the ladder). Another way to describe this is to say that a closed system cannot become more organized, at least in the long term (a closed system is one that receives no energy from outside sources). These laws do not, however, state that an open system cannot become more organized (an open system is one that does receive energy from outside sources).
Now, let’s apply all of that to evolution. The earth is most definitely an open system. It is constantly receiving energy from the sun. In fact, the sun drives nearly all life on earth. So, since the earth is an open system, there is no conflict between evolution and the thermodynamics. Let me use an example to prove that. I think we can all agree that a tree is more organized (has a higher energy state) than a seed. So, if thermodynamics worked the way that creationists claim, it should be impossible for a seed to grow into a tree, but it clearly is possible for seeds to grow. Why? Quite simply, because the earth is an open system. Even so, it is entirely possible for life to become more organized because organisms are constantly receiving energy from the sun (or from food which grew because of energy from the sun). So there is no conflict between evolution and thermodynamics.
Note: Myth#3 was edited on 5-Sept-15
Myth 4: We haven’t found any “missing links”
Odontochelys is a transitional fossil between turtles and their lizard like ancestors, complete with partially formed shell. Image via Chun et al. 2008.
The term “missing link” is a misnomer because they aren’t missing. We have hundreds of fossils that clearly represent transitions between two groups of organisms. Creationists invariably claim that these fossils are simply uniquely created organisms that happen to look like transitions, but this is a clear and enormous ad hoc fallacy because evolution predicted the existence of these fossils. If, for example, I asked you to describe what an intermediate between a turtle and its lizard-like ancestor would look like, you would inevitably describe a creature with half the features of a lizard and half the features of a turtle (e.g., a partially formed shell, a turtle like skull that still retains lizard like teeth, a somewhat specialized neck, etc.). Well guess what, that’s exactly what we see in the fossil record with species like Odontochelys and Pappochelys which have some lizard features and some turtle features. Similarly, if I asked you to describe an intermediate between a dinosaur and a bird, you would probably describe a featured dinosaur with partially formed wings and some skeletal modifications like an enlarged breastbone, but which still retains some dinosaur features like teeth. Indeed, the creature that you are imagining closely matches fossils like Archaeopteryx, Confuciusornis, and Jeholornis. The same is true for the transition for fish to amphibians, amphibians to reptiles, reptiles to mammals, etc.
In each of those cases, we have multiple fossils that are exactly what we would expect if evolution was true, and the only way that you would reject the notion that these are intermediates is if you were already convinced that intermediates don’t exist. This is the fundamental problem with creationism (and a big part of why it is pseudoscience). Creationists have determined ahead of time that no intermediates exist, so no matter how perfect a transitional fossil may be, they will always claim that it is just a unique species that happens to look like a transitional (I explained this in much more detail here and you can find a good list of intermediates here [yes, I know Wikipedia isn’t a good source, but this list is actually quite useful and you can use it as a starting point to look up the details of specific fossils in more reputable sources]).
Myth 5: Evolution isn’t science because it hasn’t been observed/repeated
First, we have to specify what we mean by “evolution.” You see, evolution on a small scale has been observed numerous times. Bacteria evolving resistance to antibiotics is the most well-known example of this, but there are many others. For example, we have been able to observe finches on the Galapagos evolve and change their beak sizes in response to droughts (Grant and Grant 2002). We have even been able to observe entirely new species form (lots of good sources here).
Nevertheless, when most people make this claim, there are generally referring to evolution over a long period of time. In other words, they are saying that we have not observed or repeated something like a relative of the T. rex evolving into a chicken. First, it is important to realize that there is no real difference between “microevolution” and “macroevolution.” Macroevolution is just an accumulation of microevolutionary steps. So if evolution on a small scale occurs (as has been observed and experimentally demonstrated) then ipso facto, evolution on a large scale occurs. One inevitably leads to the other (more details here).
Finally, the idea that we have to directly observe something and repeat the event itself in order for it to be science is a fundamental misunderstanding of science. Most science is not based on direct observation of the actual event of interest. Rather, we observe clues that are left behind by the event, and we infer information about the event from them. For example, no one has directly observed two hydrogen atoms joining an oxygen atom to form a water molecule, but we know that it happens because we can conduct chemistry experiments which give observable results that we can use to infer the sharing of electrons that lets those atoms combine. Similarly, we constantly solve crimes without either observing or repeating them because there are clues left behind that we can use to infer who committed the crime (this is known as forensic science). Even so, we do not need to observe a dinosaur evolving into a bird to know that it happened because there are clues left behind in the fossils, DNA, etc., which we use to infer evolution. There is nothing unscientific about that, and, in fact, it is how most science works. We make predictions like, “if and only if birds evolved from reptiles, then birds should share more DNA with reptiles than any other group.” We then test those predictions, and when they consistently come true, we conclude that our hypothesis is most likely correct. That is the scientific method at its finest (I explained this in more detail here).
Myth 6: Individuals evolve
Populations evolve not individuals. Evolution is just a change in the genetic composition of a population over time, so, since individuals cannot change their genetic composition, they cannot evolve. For example, if a drought comes along and destroys all seed-bearing plants except for ones with very large seeds, an individual bird with a small bill cannot evolve in response to that drought. In other words, it cannot change its genetic makeup and alter its bill size to eat the large seeds. In biological terms, it cannot adapt. As a result, the birds that have small bills will get less food and produce less offspring than the birds with large bills. This means that there will be more genes for large bills in the next generation. So the population will evolve and adapt to the drought, but the individuals will not evolve.
Myth 7: Evolution has a direction or goal
People often talk about evolution “trying to accomplish” something, or they may describe primates and other mammals as being “more evolved” than other animals, but statements like that are extremely problematic because they inherently imply that evolution has a direction or goal, which it doesn’t. Biologist often like to say that, “evolution is blind.” All that evolution can do is adapt an organism for its current environment and way of life (I’m talking specifically about evolution by natural selection here). Evolution has no foresight, and it is completely incapable of predicting what will be useful in the future, so a trait that has been selected for thousands of generations may suddenly become harmful if the environment changes.
Because evolution just adapts organisms to their current environment and way of life, it doesn’t really make sense to describe one species as “more evolved” than the other. For example, a monkey is not “more evolved” than the fly that gets its moisture from the monkey’s poop. The monkey is certainly more complex, but it’s not really more evolved because both the monkey and the fly are extremely well suited to their way of life. If you try to say that the monkey is more evolved than the fly, then you are implying that evolution has a direction, which it doesn’t.
Finally, this explains the common creationist criticism that certain species have “evolved backwards” (e.g., penguins lost the ability to fly, whales went back into the ocean, etc.). This again assumes that evolution has a direction or goal, when in reality, it’s just adapting organisms to their current environment. So, at one point in time, flight was useful so evolution selected for it and produced flying birds, but as those birds invaded the antarctic, the ability to fly was not as important as the ability to swim and stay warm, so evolution selected against adaptations for flight and produced penguins.
Myth 8: Some systems are too complex to evolve
This is one of the oldest criticisms of evolution, and it has recently resurfaced under the moniker “irreducible complexity.” The basic idea is that some systems are too complex to evolve because they aren’t functional until all of the parts are in place. For example, an eye that is missing a single piece no longer sees, and a bacterial flagellum that is missing a single protein can no longer act as a flagellum. So the argument claims that these systems could not have evolved because there would have been steps that served no useful function, and nature could not have selected for those steps. The problem is that this argument ignores the fact that evolution is blind. Traits don’t need to function for some ultimate final product in order to be selected for. Rather, if they provide any useful function at all, nature will select them. Indeed, no one has ever been able to find a truly irreducible system, and we have evolutionary pathways that explain how complex systems evolve. For example, an early precursor of the eye would have simply involved a few light sensitive cells (much like some flatworms have). They don’t function as an eye, but they still function, so nature will select for them. Similarly, the proteins that make up a flagellum all serve other functions in the cell, and we have even figured out a step-wise series of events that would form a flagellum with each step serving a useful function for the cell, even though only the final step actually serves as a flagellum. So there is just no truth to the notion that some systems are too complex to evolve (I explained this in more detail here).
Myth 9: Evolution describes the formation of the universe/the first cell
I often hear people argue that, “evolution isn’t true because blah, blah, blah…big bang” or some nonsense about how we haven’t figured out how the first cell formed. Beyond the specific issues with those arguments (which I won’t go into here), those arguments are totally irrelevant to evolution. The big bang theory deals with the formation of the universe, and abiogenesis deals with the formation of life. Evolution only comes into play after life formed. So, even if you managed to disprove the big bang or disprove abiogenesis, you would not have in any way shape or form disproved evolution. Indeed, there are some people who think that God created the first cell, then let evolution take its course. In other words, they reject abiogenesis but accept evolution (to be clear though, there is no good scientific reason to reject abiogenesis or the big bang).
Myth 10: Evolution is faith based
To anyone who makes this claim, I would like to know which part exactly you think is faith based. As I explained in #5, the fact that we did not directly observe millions of years of evolution doesn’t disqualify it as science. In fact, evolution is one of the most well supported ideas in all of science, and if you actually read Origin of the Species it is packed with evidence. Further, Darwin was an exceptional scientist and made clear predictions about what future researchers should find if his theory was correct. For example, he explicitly stated that we should find intermediate fossils, and we have (see #4). Think about that for a second. Evolution predicted the existence of organisms decades before we found them. That is an utterly incredible feat. Similarly, evolution predicted a strong agreement between the fossil record and genetics, and, once again, its predictions have come true with remarkable consistency. So if you are going to claim that evolution is based on faith, I want to know precisely what part of it you think is faith based, because there is no aspect of it which I cannot back up with empirical data.
Finally, it is worth noting that, contrary to popular perception, evolution is not inherently atheistic. Darwin was not an atheist and there are scientists who both accept evolution and believe in God. Evolution is not based on faith, and it doesn’t stem from a philosophical or religious desire to reject God. Rather, it is a scientific fact which is supported by an insurmountable mountain of evidence.
Five Misconceptions in Genetics
Students may bring a variety of misconceptions with them when they enter a study of genetics. Watch your classroom for the 5 common misconceptions listed below. If you find any of them, just use the simple explanations𠅊lso provided below—to dispel your students’ incorrect notions.
- One set of alleles is responsible for determining each trait, and there are only 2 different alleles (dominant and recessive) for each gene. After learning about simple Mendelian inheritance and sex-linked traits, students often think that it is possible to model all traits so easily and predictably. In humans, at least 3 different genes are associated with eye color. Coat color in cats is controlled by at least 6 genes. Furthermore, the number of particular alleles inherited determines the expression of some characteristics for example, the number of alleles—that you inherit from each parent—that code for production of melanin may partially determine your hair color. Inheritance of more of the alleles may lead to darker hair, while inheritance of fewer may lead to lighter hair. For traits that show a Mendelian pattern of inheritance, students often assume that there are only 2 possible alleles for a trait. This is true in some cases, but in many cases, there are more alleles for a trait. In cat-coat-color genetics, 3 different alleles of 1 gene determine the position of pigmentation on the body.
- Your genes determine all of your characteristics, and cloned organisms are exact copies of the original. While genes play a huge role in how an organism develops, environmental factors also play a role. Epigenetics is the study of heritable changes that occur without changes in the genome. The gene expression in identical mice has shown changes from factors such as diet and exposure to toxins. Further studies with identical twins have suggested that these changes can accumulate over the life of the organism. The cloning of Rainbow, a domestic cat, demonstrated 1 striking example of epigenetics. Rainbow’s coat showed calico coloration, while the coat of the clone, named Copycat, is a tabby pattern. Because Copycat and Rainbow had identical genomes, the differences must be due to epigenetic factors.
- All mutations are harmful. A mutation is a change in the genetic code of an organism. Many mutations are harmful and cause the organism not to develop properly. However, many mutations are silent and some prove beneficial. In the case of a silent mutation, the change in the genome does not change the production of the amino acid sequence and subsequent protein (remember that multiple codons may code for the same amino acid, so a change in 1 nucleotide does not necessarily change the gene product). If an organism does live with a mutation, then often the environment will determine whether the mutation is beneficial or harmful. Production of 1 protein vs. another may confer a characteristic such as a difference in coloration or in the ability to digest a resource (e.g., the ability to digest lactose or maltose instead of sucrose). The phenotypic outcome may be selected, for or against, depending on environmental factors.
- A dominant trait is the most likely to be found in the population. The term 𠇍ominant allele” sometimes conveys to students the impression that the allele is the one that exists in the greatest proportion in a population however, 𠇍ominant” refers only to the allele’s expression over another allele. Human genetics includes examples of dominant traits that do not affect the majority of the population. In fact, achondroplasia, a type of dwarfism caused by the presence of a dominant allele, is found in fewer than 1 in 10,000 live births. Huntington’s disease, a degenerative disease caused by the presence of a dominant allele, occurs at a rate of about 3 to 7 cases per 100,000 people of European descent.
- Genetics terms are often confused. Many students understand the basic ideas of genetics but need more familiarity with the terms. For example, students often struggle with the difference between a chromosome, a gene, and an allele. Chromosomes are organized structures containing proteins and a single coiled strand of DNA chromosomes are visible with a microscope only during parts of the cell cycle. Genes are units of heredity—specific sequences of DNA or RNA that create proteins with particular functions in an organism. Alleles are variants of a gene. Making sure that students have a strong foundation in the terminology can greatly improve their understanding of genetics and prevent misconceptions.
Dispelling these 5 misconceptions will help students better understand genetics information and activities that you plan for both the classroom and the lab. They will also realize there are many influences on the way living things develop genetically over time.
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Good enough is fine! Organisms do not need to achieve perfection, and it is not a race to climb up the ladder. They just need to be fit enough to survive and reproduce. Also ‘fitness’ depends on the environment. When the environment changes, a fit organism’s adaptation may become less successful (thus, the organism may no longer be adapted to the environment).
2) Evolution means that life changed ‘by chance’.
Although mutations do occur by chance and are random, selection of these mutations is not random. The most advantageous traits are selected for by the environmental conditions (natural selection).
3) Natural selection involves organisms ‘trying’ to adapt.
Organisms do not try to adapt. The process of natural selection leads to some members of a group to survive or reproduce better depending on the characteristics they have. There is no plan or choice involved.
4) Evolution is just a “theory” not fact.
This misconception stems from a mix-up between casual and scientific use of the word theory. In everyday language, theory is often used to mean a hunch with little evidential support. Scientific theories, on the other hand, are broad explanations for a wide range of phenomena. In order to be accepted by the scientific community, a theory must be strongly supported by many different lines of evidence. Evolution is a well-supported and broadly accepted scientific theory it is not ‘just’ a hunch.
5) Humans are derived from monkeys.
No. We share a common ancestor, but we are not derived from the monkeys we see today. Modern monkeys share a distant ancestor with humans, and that ancestor did possess characteristics common to all primates. However, they were not the same as modern monkeys. So although man and monkeys both came from a monkey-like species millions of years ago, humans did not evolve directly from the modern monkeys we see today.
6) Humans were around at the same time as dinosaurs.
Not true! This is a common misconception due to unrealistic movies and cartoons. Dinosaurs inhabited the earth and became extinct 65 million of years before humans came into existence!!Flintstones are just a fun cartoon!
7) Religion and Evolution cannot co-exist.
This is not true. Evolution is a scientific fact, religion is a matter of faith. The same way as a child learn maths and history, they can have RE and Science lessons. Evolution should be taught as scientific fact not as an alternative theory to religion.
Evolution can comfortably be taught as the science that explains how organisms change over time. Evolution as a science makes no statements about the existence of god, and is not necessarily incompatible with its existence
Evolution = Progress
This may be the most common misconception of all&hellip the idea that those species that evolved later are somehow &ldquobetter&rdquo or more advanced than those that came before. It is easy to believe this from an anthropocentric worldview &ndash We are the most powerful species on the planet, and are at the top of the food chain, so we are evolution&rsquos &ldquofurthest step&rdquo.
However, there are species and types of species that have survived for incredibly long periods of time, throughout catastrophic wipeouts of other species (e.g., certain sharks, shrimp, and crabs &ndash all of which have been around for hundreds of millions of years). The idea of evolution as a ladder, with humans at the top of it, is totally incorrect.
Evolution is best expressed as a tree, with millions of branches and divergences over the course of history. Some specific traits have taken tens of millions of years to develop, and just because they are in a species that is perceived as &ldquosimple&rdquo or &ldquobasic&rdquo does not mean they are less advanced than humans, elephants, dolphins or chimpanzees. The outcomes of evolution cannot be measured qualitatively or temporally in the grand picture of life on this planet, every species and their journey of evolution is rather incredible.
Now, the next time someone raises some of these common concerns about the validity of evolution, you can quickly set them on the right track and help them start enjoying the wondrous diversity on the planet, rather than being suspicious of this &ldquotheory&rdquo.
Evolution is one of the cornerstones of the life sciences. It has been demonstrated countless times in different ways, and it is supported by multiple items of evidence.
Still, some people take issue with evolution for all sorts of non-scientific reasons and present faulty arguments against it. Advocates of the pseudo-scientific “Intelligent Design” theory go as far as claiming that features in forms of life on earth were designed by an intelligent being, and were created as we find them today.
Unfortunately, these arguments appear in public discourse and sometimes in school curricula, especially in the U.S., where they are sometimes shown as explanations equally valid to those derived from scientific reasoning.
Although “Davidson Online” features several pieces explaining evolution, we have yet to tackle the arguments that challenge it. Here I will try to sort things out by presenting the main claims against evolution and then scientifically debunking them. As you will see, most of the arguments derive from basic misunderstandings of evolutionary theory or other scientific principles.
“Evolution is just a theory”
This argument stems from a misunderstanding of scientific terms. According to the scientific method, a “theory” is an explanation grounded in a large amount of evidence. Among scientists, evolution is considered a very solid, well-trusted idea, and one of the most fundamental laws of nature. In fact, evolution is a theory just like thermodynamics and gravity. They are all falsifiable, but so far no credible evidence has been offered to disprove any of them, including evolution.
Many people confuse the word “theory” with “hypothesis”(an educated guess), which still needs to be tested, experimentally or otherwise.
“Evolution explains the origin of life”
Evolution does not explain the origin of life, but how it developed after it appeared on earth. In fact, the scientific definition of evolution is “a change in the allele distribution in a gene pool”, where “allele distribution” is how often a trait appears and “gene pool” refers to the collective genetic material of a reproducing population of a life form. In other words, to have evolution there needs to be a pre-existing gene pool, meaning life already must exist. Some theories attempt to explain the origin of life, notably including the abiogenesis theory. Evolution is not concerned with this question.
“If people descended from apes, why are there still apes?”
In each generation, each species must face natural selection. If a species is adapted to its surroundings, meaning it can survive and produce another generation, it will remain over time. If it can’t do these things, for any reason, then it becomes extinct.
One species might evolve from another, which is called an ancestral species, but the ancestral species might still be adapted enough to its surroundings to keep existing and surviving. Moreover, the newer species might go extinct while the ancestral one might survive.
All in all, what determines the extinction of a species is natural selection, not whether new descendent species have emerged as “branches” of the ancestral population.
“Evolution happens only at the micro level, not the macro level”
Many evolution deniers tend to separate evolution into two levels. The “micro level” refers to changes in single traits by point mutations, such as in the evolution of antibiotic resistance in bacteria, whereas the “macro level” refers to the appearance of new organs, physiological systems and species, such as the development of the eye.
Although I have looked for a precise definition of each purported “subtype” of evolution, and for criteria to tell them apart, I could not find any.
There’s a good reason for that: The definition of “macro-evolution” changes as new evidence comes to light. Once, the “flagship” of evidence against macroevolution was the eye, but after a study was published showing how an eye could develop in a small number of steps, where each step confers an evolutionary advantage, different evidence had to be sought. Nowadays, I see that macroevolution discussions refer to “irreducible complexity”. Examples include genes encoding proteins that are claimed to have complex yet essential functions, which they could not have evolved from an ancestral gene. Once, the bacterial flagella were presented as evidence for irreducible complexity, until that was debunked as well. Nowadays, hemoglobin serves as the poster child for this claim.
My answer to this claim is simple: separating micro-evolution from macro-evolution is completely misguided. Just as the force of gravity acting on two sand grains in a vacuum is the same force acting on two galaxies in space (“micro-gravity” and “macro-gravity”, respectively), it would be wrong to arbitrarily distinguish small changes in living species from larger changes that accumulate over time.
“Evolution is wrong because there are so many missing links between species”
According to evolutionary theory, all species on earth have a common ancestor. Similar pairs of species diverged from their last common ancestor fairly recently, whereas other, more different pairs of species diverged further back in history. Some transitional populations of species exhibit traits common to both an ancestral group and its derived descendant group. Much of the information we have about transitional species comes from the fossil record. Unfortunately, fossils are hard to come by because fossilization is a very rare event that requires many different conditions in a particular order, over time. Naturally, these conditions don’t occur everywhere at all times, so only few creatures have left fossils for us to discover. Most likely, many species that existed on earth left no fossil record, but that doesn’t mean they didn’t exist.
Still, the fossil record we do have contains many transitional fossils, all of which support evolution.
“Evolution contradicts the second law of thermodynamics”
Of all the arguments I have seen so far, this must be the most ridiculous. The second law of thermodynamics says that for an irreversible process in an isolated system, the thermodynamic state variable known as entropy (a term associated with disorder) is always increasing. Some people, including some scientists, claim that since evolution creates order, it contradicts the second law of thermodynamics.
As the first step to challenge this, we should look at whether evolution creates order. It doesn’t. But this argument is moot for other, more important reasons.
Firstly, the second law of thermodynamics only refers to total entropy. In some local areas, however, entropy can be lowered and order can be increased, at the expense of an entropy increase in the surroundings, over time.
Secondly, the second law of thermodynamics only refers to isolated systems, which receive no energy or matter from outside, and earth is not such a system. It takes up large amounts of energy from the sun over billions of years. If we sum the earth and the sun together for the entropy calculations, we’ll find that total entropy does increase, although locally, some “islands” of order are maintained.
“Life is so complex, it must have been designed”
Here we find a logical fallacy. Why does something too complex for us to understand or explain require an intelligent being to design it? The fact we cannot explain something does not imply that someone else can.
Moreover, many design failures in living organisms are tell-tale signs for how life evolved gradually, without any preconceived plan. The vagus nerve serves as a good example for this. In mammals, it leaves the brain, extends to the heart and goes back up to the larynx. In giraffes, the anatomical constraints are so extreme, the vagus nerve must extend up to almost five meters until is reaches the larynx.
In other branches of the tree of life, such as in fish, the vagus nerve is much shorter, because the brain, the heart and the gill arches are all next to each other. But as these structures evolved over time, and as the neck formed and extended over time, the vagus nerve got “stuck” on the wrong side of the heart and had to do a long detour to enervate the larynx. Any “intelligent” design would have planned a much shorter route.
“How do organisms pre-emptively evolve traits they will only need in the future?”
Quite simply, they don’t. Populations of organisms just adapt to specific habitats all the time. Each generation, traits are put to the test of natural selection. If a trait confers a fitness advantage, it is more likely to be found in the next generation. If it confers a disadvantage, the organism is less likely to survive and reproduce, and the trait is less likely to spread throughout the population. Small changes in traits add up to larger changes. Environments change and organisms’ traits closely follow those changes, step by step, and continuously over time, never pre-emptively.
“So how are complex systems formed?”
A series of small changes can add up to a big change. This requires each change to confer a relative advantage compared with the previous state. When these changes add up, we can observe complex systems evolving in living organisms.
For example, let’s have a look at the eye, which everyone can agree is quite a complex system. Being able to see gives organisms a huge advantage over their blind counterparts. In 1994, a study by Nilsson and Pelger showed that an eye could develop step by step from a tissue of light-sensitive cells, where each step confers a relative fitness advantage. What’s more, they also estimated that the eye could have evolved over the course of 364,000 years, which, in evolutionary terms, is a brief moment. So, all in all, even complex systems like eyes can evolve gradually.
“How do the ‘more advanced’ life forms sexually reproduce, as they are genetically different from the rest of the population?”
Small genetic changes don’t necessarily create a reproductive barrier. Just as a Pinscher dog can mate with a Rottweiler, despite their physical differences, so an organism with a variant trait can usually reproduce with other members of the same population. If the trait precludes reproduction, it won’t be found in the next generation, and before long, it will disappear from the gene pool.
“So where do new species come from?”
A biological species is a group of organisms that can reproduce with one another. As soon as organisms from one group cannot reproduce with organisms from another group, they are defined as two separate populations of two separate species.
Let’s say we have a population of gazelles. An earthquake creates a rift valley separating the population into two groups that cannot meet each other anymore. As time goes by, each group adapts to the changes in its environment. Over time, so many genetic differences have accumulated in each of the groups that a gazelle from one group cannot reproduce with a gazelle from the other group anymore. Once this reproductive barrier is in place, the two groups will evolve separately, and are considered two separate species with a common ancestor, preceding the earthquake.
There are many more claims out there concerning evolution and I invite you to write them in our comments section. I will try to answer each point, and the most interesting arguments will be added to the article.
Erez S. Garty, Ph.D.
Editor in Chief, Davidson Online
Davidson Institute of Science Education
Weizmann Institute of Science
Article translated from Hebrew by Aviv J. Sharon, M.Sc. student at the Weizmann Institute of Science.
Note for Surfers
If you find the explanations unclear or have further questions, please drop us a line on the forum. We welcome your comments, suggestions and feedback.
We explored student composite responses to the instrument questions about natural selection to determine whether the diversity of misconceptions changed from pre- to postcourse in the treatment group. A misconceptions score of 6 was the highest possible diversity score in this measure. Precourse, the mean diversity of misconceptions employed by the active-learning group was 2.47 (SD 2.0). Precourse, 40.4 percent of the students employed no misconceptions or one misconception, 17.2 percent employed two or three misconceptions, and 42.4 percent employed four or more misconceptions.
Although the frequency of misconceptions decreased significantly after the course ( figure 4), there was no significant change in the diversity of misconceptions students employed (t = 0.198, 172 df, p = 0.843 figure 5). Postcourse, similar percentages of students employed no misconceptions (30.3 percent precourse versus 30.5 percent postcourse), whereas a slight decrease in the percentage of students using four or more different misconceptions occurred (42.4 percent precourse versus 35.4 percent postcourse). In the traditional-learning group, 14 percent of students postcourse had no misconceptions (compared with 30 percent in the treatment group). On average, however, students in the active-learning group who had misconceptions displayed misconception magnitudes (2.41) similar to those of students in the traditional-learning group (1.91).
To determine whether the context of instrument implementation was accurately capturing students' use of misconceptions, we compared student misconception magnitudes between the postcourse “speeding up evolution” question and the extra-credit opportunity discussed previously. We found that the postcourse and extra-credit instruments captured comparable magnitudes of misconceptions ( figure 6). Thus our instrument provided a reliable estimate of student misconceptions in different motivational contexts.
Thinking Evolutionarily: Evolution Education Across the Life Sciences: Summary of a Convocation (2012)
Biological evolution is a difficult concept to learn, as several people at the convocation emphasized. It involves complex biological mechanisms and time periods far beyond human experience. Even when students have finished a high school or college biology course, there is much more to learn about the subject.
The difficulty of teaching evolution both complicates and invigorates research on evolution education. To present what is known and not known about the teaching and learning of evolution&mdashwhich is a standard feature of convening events organized by the Academies&mdashRoss Nehm, associate professor of science education at Ohio State University, gave an overview of the research literature on evolution education and then talked in more detail about his own research.
The literature on teaching and learning about evolution is extensive. In 2006 Nehm reviewed 200 of more than 750 papers published thus far about evolution education, identifying both strengths and limitations of the approaches taken in those studies (Nehm, 2006). This literature demonstrates that the general public, high school students, undergraduates, biology majors, science teachers, and medical students all have low levels of knowledge and many misconceptions about evolution (Nehm and Schonfeld, 2007). Furthermore, as with other areas of science, many of the same misconceptions persist in all of these populations. &ldquoThey don&rsquot
go away,&rdquo said Nehm. &ldquoWhatever instruction is happening at early levels, it&rsquos not ameliorating the problems that we have.&rdquo
In education, the only way to make robust causal claims is through a randomized controlled trial (RCT), but no such trials have been conducted for evolution education. &ldquoIf you want to make causal claims, there is no causal literature to refer to.&rdquo
Fortunately, other research tools can be used with educational interventions to draw conclusions that can guide policy. A group receiving an intervention can be compared with a group not receiving the intervention. Interventions can be done without a comparison group&mdashfor example, by looking at a group before and after an intervention. Survey research can yield associations, although survey research cannot determine whether these associations are causal. Finally, case studies, interviews, and other forms of qualitative research can reveal new variables and possible associations.
Nehm&rsquos 2006 review of the literature found no intervention studies with randomized control groups, 6 intervention studies with comparison groups, and 24 other studies that employed various intervention techniques. Also, some of the interventions were quite brief&mdashjust one to three weeks&mdasha period during which substantial changes are unlikely to occur, given the difficulties of teaching evolution. One conclusion is obvious, Nehm said: &ldquoWe need to do some randomized controlled trials to see what works causally in terms of evolution education.&rdquo
Nehm also pointed out that documenting learning outcomes is critically important in education research. According to the report Knowing What Students Know: The Science and Design of Educational Assessment (National Research Council, 2001), &ldquoassessments need to examine how well students engage in communicative practices appropriate to a domain of knowledge and skill, what they understand about those practices, and how well they use the tools appropriate to that domain.&rdquo Yet most tests today, including those that dominate biology curricula, assess isolated knowledge fragments using multiple choice tests. Students may be learning about evolution, &ldquobut if we can&rsquot measure that progress, we can&rsquot show that what we&rsquore doing has any positive effect. So we need assessments that can measure the way people actually think.&rdquo
The problems caused by inadequate metrics are particularly obvious in the literature on teacher knowledge of evolution, Nehm said. Only five intervention studies exist, and three of them assess teacher&rsquos knowledge of evolution using a multiple choice or Likert scale test (Baldwin et al., 2012). This lack of careful metrics &ldquois really concerning,&rdquo said Nehm. Evolution assessments must be developed that meet quality control standards established by the educational measurement community, or robust claims, causal or otherwise, cannot be made.
In summary, research has established key variables that should be investigated and many possible beneficial interventions. But the research literature on evolution education lacks robust, causal, generalizable claims relating to particular pedagogical strategies and interventions. It also lacks measurement instruments that meet basic quality control standards and capture authentic disciplinary practices. Finally, the research lacks consistent application of measurement instruments across different populations. &ldquoThis is a call to action,&rdquo said Nehm. &ldquoWe need to gather and do a national randomized controlled trial of some of the most likely and agreed upon variables and test their causal impact on students&rsquo learning of evolution.&rdquo
In his own research, Nehm and his colleagues have been studying how different groups, from novice to expert, think about problems. 1 Using performance-based measures in which research participants are asked to solve evolutionary problems, they have looked at 400 people&mdashincluding non-majors who have completed an introductory biology course, students who have completed a course in evolution, students who have completed an evolution course as well as more advanced coursework, and a group of biology Ph.D. students, assistant professors, associate professors, and full professors (Nehm and Ha, in preparation).
The study measured people&rsquos ability to explain evolutionary change across a variety of contexts, not through multiple choice questions. In general, this technique revealed many more gaps in evolutionary understanding than would simpler assessments. For example, students have a harder time explaining evolutionary change (in writing or orally) than recognizing accurate scientific elements of an explanation when presented in a multiple choice test (Nehm and Schonfeld, 2008). Or, as Nehm put it, knowing the parts and tools needed to assemble furniture does not mean that you can build it. Students may have a lot of knowledge about evolution but not be able to use that knowledge to create a functional explanation. &ldquoThis is a tough competency,&rdquo explained Nehm. &ldquoIf you asked any of your students, and I encourage you to do this, &lsquoCan you explain how evolutionary change occurs?&rsquo you will be startled at their inability to articulate their understanding because they are never asked to do that.&rdquo
In addition, people have a tendency to mix naïve and scientific information together in their explanations. Naïve ideas include, for example, the notions that the needs of an organism drive evolutionary change or
1 A summary of the general research on differences between novices and experts can be found in National Research Council (2000).
Myth 5 - Evolution is just a theory.
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.
Biologists use the theory of evolution to explain a wide variety of observations about life on earth. For example, evolution serves as a model to help us understand why an animal is on the verge of extinction. Climate change may place additional pressures on species who do not have traits to survive in warmer climates. In 1995, conservation officers attempted to save the near extinct Florida Panther by introducing cougars from Texas into their habitat. The effort worked, adding much needed diversity to the struggling population of panthers and saving them from extinction. This plan would not have worked if scientists did not understand the relationship between the two cat populations based on the model of evolution.
___ 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. _______________________ | _____________________________________________
___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
10. Synthesis: Why is evolution considered the foundation theory of biological sciences? Use information from the text above to develop your answer.
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