Unfortunately, humans seem to thrive on controversy. Though people may come from diverse economic, social, and cultural backgrounds, there is one thing that we all love: Arguing. In fact, we’ll even argue about things that experts are decidedly *not* arguing about.
Case in point, the Pew Research Center recently conducted a survey (between March 21 and April 8, 2013) among a national sample of 1,983 adults. This survey dealt with individual views regarding evolution. The survey was conducted by professionally trained interviewing staff under the direction of Princeton Survey Research Associates International. According to the analysis, six-in-ten Americans (60%) say that “humans and other living things have evolved over time.” That’s a bit comforting; however, not all of the findings are inspiring.
A third of Americans (33%) reject the idea of evolution, asserting that “humans and other living things have existed in their present form since the beginning of time.” These numbers are troubling, as this is a process that is accepted by 99% of experts in the field. Ultimately, this means that there is a bit of a disparity between what experts assert and the public is willing to believe. Of course, the scientific community does not operate on consensus; it operates on evidence and observation. Nonetheless, the numbers are problematic in that they say something about who the public is willing to trust (hint: it's not their own judgement or critical evaluation of the evidence).
According to Yale studies, people only seriously consider evidence if it is presented/endorsed by someone who subscribes to their cultural beliefs i.e., if an individual has to believe an expert or a person who shares their cultural values (religious, political, economic, or otherwise), they will go with the person who has a similar belief structure. According to the researchers' findings, "people tend to keep a biased score of what experts believe, counting a scientist as an 'expert' only when that scientist agrees with the position they find culturally congenial."
Consequently, the disparity between experts and the general public indicates that the public is either misinformed or openly refusing to accept scientific evidence brought forth by the scientific method (neither one is particularly good news for any who are concerned about scientific literacy). And unfortunately, these numbers aren't changing. A 20006 survey of 32 European countries, the United States, and Japan revealed that only Turkey is less willing than the US to accept evolution as fact; the numbers in the US have not altered much in that time.
Of those who responded to the 2013 survey by asserting that they accept the evidence supporting evolution, about half of those claim that evolution is “due to natural processes such as natural selection” (just 32% of the American public overall accept evolution by natural selection). Many Americans believe that a supreme being played a role in the process of evolution, asserting that “a supreme being guided the evolution of living things for the purpose of creating humans and other life in the form it exists today.”
The religious debate aside, the process of natural selection is well documented. In essence, per natural selection, any trait that gives an advantage in relation to survival increases the chances of survival for the organism that possess this trait; therefore, this organism has a greater chance of passing that trait on to its offspring. This trend will progress surprisingly quickly until the entire population possesses the "superior trait" (the trait better suited for survival). Of course, one of the things that natural selection would manage would be the semi-random traits that are brought about by mutation. Anything beneficial would automatically be more likely to spread throughout the gene pool. The adaptability (evolution) of Staphylococcus aureus is excellent evidence for the theory of evolution by natural selection.
Likewise, the evidence supporting evolution is substantial. Many people believe that we can’t observe evolution, but contrary to popular belief, we can witness evolutionary events; however, perhaps I should clarify — by observing it, I mean that we have observed results in laboratory and natural conditions that are predicted by evolution, and we see the types of changes that would be expected if evolution were true. Of course, we can’t really observe our own evolutionary history (at least, not until we develop time travel), and witnessing species transitions is difficult as it takes tens of thousands or hundreds of thousands of years (even in simple organisms [like bacteria] it takes a long, long time).
One good example of the evidence for evolution can be found in the "London Underground Mosquito," or more formally known as Culex pipiens molestus. It appears that this mosquito appeared around the early 20th century. On the surface, one might think this species of mosquito just happens to live underground, but the conditions endured by the underground and above ground variants actually created huge alterations in the two mosquito communities.
The above ground mosquitoes (which the undergrounds came from) hibernate during the winter, only bite birds, and are tolerant to cold weather. The underground variant is active year round, bites mammals (including dogs, rats, and humans), and is intolerant to the cold.
However,the behavior of these two mosquitoes isn’t where it stops. We’ve noticed that, in addition to acting completely differently, they have become genetically dissimilar to each other. They will no longer inter-breed, and even the Allele frequencies are different for the two. After a good bit of research, we have come to the conclusion that these, though originally the same, are now two different species of mosquito. Why did this happen? Well, it is just the principals of evolution at work. The original population was separated in two very different environments. After a long enough time, gene drift and adaptation gave us two different results.
Despite all this evidence (and there is a lot more evidence than what is detailed here), many continue to assert that evolution is "just a theory." However, it is important to note that theories cannot be proven per se, but a theory is not just a random idea that has no scientific backing. Ultimately, when people say that evolution can’t be tested, or assert that it is only a theory, they are improperly defining the term “theory.” In science, a theory is not simply a hypothesis–an untestable and unprovable idea. Instead, a theory is “a testable model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or observation.” Thus, calling something “a theory” is not derogatory in science.
The way a theory works is pretty simple: it has to make a clear, testable prediction, and (preferably) make a minimum of new assumptions. So testing evolution is fairly simple. We look at the predictions made by the theory, and then compare them to what we can observe. So far evolution has done a very good job of explaining the things that we have observed, and also at predicting new results as we uncover new ways of testing.
Want to learn more about the evidence that supports evolution? Check out these resources:
- Common Misunderstandings of Evolution: Part 1
- Common Misunderstandings of Evolution: Part 2
- Common Misunderstandings of Evolution: Part 3
*Some of the defining terms and examples of evidence listed here were republished from previous FQtQ articles.
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