Misconceptions about the history of life and how it came about are unfortunately very common. Most of these misunderstandings have to do with assumptions that evolution proceeds in a particular direction or that individual living things can choose to adapt.
Here we examine 5 common misunderstandings about evolution and how it works:
Misconception: “Evolution is a theory about the origin of life.”
Response: Evolutionary theory deals mainly with how life changed after its origin. Science does try to investigate how life started (e.g., whether or not it happened near a deep-sea vent, which organic molecules came first, etc.), but these considerations are not the central focus of evolutionary theory. Regardless of how life started, afterwards it branched and diversified, and most studies of evolution are focused on those processes.
Misconception: “Evolution is like a climb up a ladder of progress; organisms are always getting better.”
Response: It is true that natural selection weeds out individuals that are unfit in a particular situation, but for evolution, “good enough” is good enough. No organism has to be perfect. For example, many taxa (like some mosses, protists, fungi, sharks, opossums, and crayfish) have changed little over great expanses of time. They are not marching up a ladder of progress. Rather, they are fit enough to survive and reproduce, and that is all that is necessary to ensure their existence.
Other taxa may have changed and diversified a great deal—but that doesn’t mean they got “better.” After all, climates change, rivers shift course, new competitors invade—and what was “better” a million years ago, may not be “better” today. What works “better” in one location might not work so well in another. Fitness (a genotype’s success at reproducing (the more offspring the genotype leaves, the higher its fitness)) is linked to environment, not to progress.Misconception: “Evolution means that life changed ‘by chance.’ ”
Response: Chance is certainly a factor in evolution, but there are also non-random evolutionary mechanisms. Random mutation is the ultimate source of genetic variation, however natural selection, the process by which some variants survive and others do not, is not random.
For example, some aquatic animals are more likely to survive and reproduce if they can move quickly through water. Speed helps them to capture prey and escape danger. Animals such as sharks, tuna, dolphins and ichthyosaurs have evolved streamlined body shapes that allow them to swim fast. As they evolved, individuals with more streamlined bodies were more likely to survive and reproduce. Individuals that survive and reproduce better in their environment will have more offspring (displaying the same traits) in the next generation. That's non-random selection. To say that evolution happens “by chance” ignores half of the picture.
Misconception: “Natural selection involves organisms ‘trying’ to adapt.”
Response: Natural selection leads to adaptation, but the process doesn’t involve “trying.” Natural selection involves genetic variation and selection among variants present in a population. Either an individual has genes that are good enough to survive and reproduce, or it does not—but it can’t get the right genes by “trying.”
Misconception: “Natural selection gives organisms what they ‘need.’ ”
Response: Natural selection has no intentions or senses; it cannot sense what a species “needs.” If a population happens to have the genetic variation that allows some individuals to survive a particular challenge better than others, then those individuals will have more offspring in the next generation, and the population will evolve. If that genetic variation is not in the population, the population may still survive (but not evolve much) or it may die out. But it will not be granted what it “needs” by natural selection.
Evidence Regarding Evolution
Many of the misconceptions about the evidence supporting evolution have been planted in the minds of the public through antievolution propaganda. The following notions may appear compelling at first glance, but are easily debunked with a little information.
Misconception: “Evolution is ‘just’ a theory.”
Response: Scientific theories are explanations that are based on lines of evidence, enable valid predictions, and have been tested in many ways. In contrast, there is also a popular definition of theory—a “guess” or “hunch.” These conflicting definitions often cause unnecessary confusion about evolution.
The scientific definition of “theory” should not be confused with the way the term is commonly used to mean a guess or a hunch. In science, a theory means much more and is far more well-founded. The “Theory of Evolution” is an evidence-based, internally consistent, well-tested explanation of how the history of life proceeded on Earth—not a hunch. Understanding the role of theory in science is essential to scientists and vital to the informed citizen.
(Find out how we know what happened when here: www.evolution.berkeley.edu)
Misconception: “Evolution is a theory in crisis and is collapsing as scientists lose confidence in it.”
Response: Scientists do not debate whether evolution (descent with modification) took place, but they do argue about how it took place. Details of the processes and mechanisms are vigorously debated. Antievolutionists may hear the debates about how evolution occurs and misinterpret them as debates about whether evolution occurs. Evolution is sound science and is treated accordingly by scientists and scholars worldwide.
The tentative nature of science
Scientists will acknowledge that their results are always tentative. This does not mean that their ideas are poorly supported but that science is always ready to modify or reject ideas as new information is acquired. Tentativeness reflects an attitude of honesty and openness, not weakness of argument.
Misconception: “Gaps in the fossil record disprove evolution.”
Response: The fact that some transitional fossils are not preserved does not disprove evolution. Evolutionary biologists do not expect that all transitional forms will be found and realize that many species leave no fossils at all. Lots of organisms don't fossilize well and the environmental conditions for forming good fossils are not that common. So, science actually predicts that for many evolutionary changes there will be gaps in the record.
Also, scientists have found many transitional fossils. For example, there are fossils of transitional organisms between modern birds and their theropod dinosaur ancestors, and between whales and their terrestrial mammal ancestors.
Misconception: “Evolutionary theory is incomplete and is currently unable to give a total explanation of life.”
Response: Evolutionary science is a work in progress. New discoveries are made and explanations adjusted when necessary. And in this respect, evolution is just like all other sciences. Research continues to add to our knowledge. While we don’t know everything about evolution (or any other scientific discipline, for that matter), we do know a great deal about the history of life, the pattern of lineage-splitting through time, and the mechanisms that have caused these changes. And more will be learned in the future. To date, evolution is the only well-supported explanation for life’s diversity.
Misconception: “The theory of evolution is flawed, but scientists won’t admit it.”
Response: Scientists have examined the supposed “flaws” that creationists claim exist in evolutionary theory and have found no support for these claims. These “flaws” are based on misunderstandings of evolutionary theory or misrepresentations of evidence. Scientists continue to refine the theory of evolution, but that doesn’t mean it is “flawed.” Science is a very competitive endeavor and if “flaws” were discovered, scientists would be more than glad to point them out.
Misconception: “Evolution is not science because it is not observable or testable.”
Response: Evolution is observable and testable. The misconception here is that science is limited to controlled experiments that are conducted in laboratories by people in white lab coats. Actually, much of science is accomplished by gathering evidence from the real world and inferring how things work. Astronomers cannot hold stars in their hands and geologists cannot go back in time, but in both cases scientists can learn a great deal by using multiple lines of evidence to make valid and useful inferences about their objects of study. The same is true of the study of the evolutionary history of life on Earth, and as a matter of fact, many mechanisms of evolution are studied through direct experimentation as in more familiar sciences.
Misconception: “Most biologists have rejected ‘Darwinism’ (i.e., no longer really agree with the ideas put forth by Darwin and Wallace).”
Response: Darwin’s idea that evolution generally proceeds at a slow, deliberate pace has been modified to include the idea that evolution can proceed at a relatively rapid pace under some circumstances. In this sense, “Darwinism” is continually being modified. Modification of theories to make them more representative of how things work is the role of scientists and of science itself.
Thus far, however, there have been no credible challenges to the basic Darwinian principles that evolution proceeds primarily by the mechanism of natural selection acting upon variation in populations and that different species share common ancestors. Scientists have not rejected Darwin’s natural selection, but have improved and expanded it as more information has become available. For example, we now know (although Darwin did not) that genetic mutations are the source of variation acted on by natural selection, but we haven’t rejected Darwin’s idea of natural selection—we’ve just added to it.
Implications of Evolution
Evolution has one implication—it explains the history of life. Other implications allegedly derived from evolutionary theory have been used to support the denial of evolution or to justify inhumane behavior. The following two misconceptions are typical of what you might encounter.
Misconception: “Evolution leads to immoral behavior. If children are taught that they are animals, they will behave like animals.”
Response: Humans are members of the animal kingdom. We share anatomical and biochemical traits with other animals, and there are many behaviors that we share—we care for our young, we form cooperative groups, etc. There are other behaviors that are specific to particular animals. In this sense, humans act like humans, slugs act like slugs, and squirrels act like squirrels. It is unlikely that children, upon learning that they are related to all other animals, will start to behave like jellyfish or raccoons.
Linking immoral or inappropriate behavior to evolution makes no sense. Morality is not based on what is, but on what ought to be.
Misconception: “Evolution supports the idea that ‘might makes right’ and rationalizes the oppression of some people by others.”
Response: In the nineteenth and early twentieth centuries, a philosophy called “Social Darwinism” arose from a misguided effort to apply lessons from biological evolution to society. According to this view, society should allow the weak and less fit to fail and die, and that this is not only good policy, but morally right. Supposedly, evolution by natural selection provided support for these ideas. Pre-existing prejudices were rationalized by the notion that colonized nations, poor people, or disadvantaged minorities must have deserved their situations because they were “less fit” than those who were better off. This misapplication of science was used to promote social and political agendas.
The “science” of Social Darwinism was refuted. Biological evolution has stood the test of time, but Social Darwinism has not.
Evolution and Religion
The alleged incompatibility of religion and evolution has been used as a way of persuading people to deny the history of the Earth. The following misconception is dependent on a misunderstanding of the functions of both science and religion.
Misconception: “Evolution and religion are incompatible.”
Response: Religion and science (evolution) are very different things. In science, only natural causes are used to explain natural phenomena, while religion deals with beliefs that are beyond the natural world.
The misconception that one always has to choose between science and religion is incorrect. Of course, some religious beliefs explicitly contradict science (e.g., the belief that the world and all life on it was created in six literal days); however, most religious groups have no conflict with the theory of evolution or other scientific findings. In fact, many religious people, including theologians, feel that a deeper understanding of nature actually enriches their faith. Moreover, in the scientific community there are thousands of scientists who are devoutly religious and also accept evolution.
Teaching Evolution
Misconceptions about what should be taught in the science classroom stem from confusion about the nature of science itself. Science is about figuring out how things work and relies on empirical knowledge, not faith. Antievolutionists have tried to confuse science and religion, leading to the following misconceptions in the minds of some members of the public.
Misconception: “Teachers should teach ‘both sides’ and let students decide for themselves. ”
Response: Given the wide variety of religious views about creation, there are not simply "two sides" to be compared — and, in any case, these views are not science and do not belong in a science classroom. In science class, students should have opportunities to discuss the merits of arguments within the scope of science. For example, students might debate exactly where birds branched off of the tree of life: before dinosaurs or from within the dinosaur clade. In contrast, a debate pitting a scientific concept against a religious belief has no place in a science class and misleadingly suggests that a "choice" between the two must be made. The "fairness" argument has been used by groups attempting to insinuate their religious beliefs into science curricula.
Misconception: “Evolution is itself ‘religious,’ so requiring teachers to teach evolution violates the First Amendment.”
Response: Evolution is science. The study of evolution relies on evidence and inference from the natural world. Thus it is not a religion. Supreme Court and other Federal court decisions clearly differentiate science from religion and do not permit the advocacy of religious doctrine in science (or other public school) classes. Other decisions specifically uphold a school district’s right to require the teaching of evolution.
You can take a "Teacher's Quiz" at the Berkeley "Understanding Evolution For Teachers" Website.
Learn much more at http://evolution.berkeley.edu and at The National Center For Science Education.
The Greatest Show on Earth by Richard Dawkins
