He wrote an article for Evolution: Education and Outreach in which he describes misrepresentations of evolution in textbooks (Padian, 2013). Since he is a prominent leader in the fight against creationism, we need to pay attention when he tells us how evolution should be taught in public schools.
Before examining some of those "misconceptions," let's review some earlier papers in Evolution: Education and Outreach. The very first issue contained an article by John N. Thompson where he defined evolution as ...
Evolution is quite simply heritable change in the genetic structure of a population. There is nothing in this or any similar standard definition of evolution that requires that genetic change in the average size, shape, or any other trait be maintained for a hundred, a thousand, or a million years before it can truly be called evolution. (Thompson, 2007)Unfortunately, Thompson is under the mistaken impression that natural selection is the only significant mechanism of evolution but that's not the point. The point it that he, and many others, see evolution as a continuous and ongoing process that includes the minor fluctuations that Kevin Padian dismisses.
Here's how Thompson described it in his 2007 article ...
These continual small evolutionary changes in populations result in those populations meandering back and forth in their average sizes, shapes, physiological tolerances, and behaviors over time. These ongoing small evolutionary changes are what keep species in the evolutionary game. The average appearance of a species may not change much over time but populations are continually evolving as they respond to slight changes in their environments.I don't agree with Thompson because he attributes changes in allele frequencies to slight changes in the environment when, in fact, these are due to drift. However, the point is that small changes in populations are the basic stuff of evolution.
Kevin thinks we should be teaching more macroevolution in school (Padian, 2010). He is partly motivated by a desire to confront creationists who, by and large, don't have a problem with microevolution. In his 2010 article, Kevin says ...
For decades this problem has been staring us in the face: creationists are fine with microevolution (changes within populations), because they just see it as noise in the system, variation within created kinds. But they abhor macroevolution because it implies that major groups can evolve from other major groups, there is a continuum of life, and therefore even humans might be part of that continuum.I'm not sure there's a real deficit in teaching macroevolution and the history of life but I do think students lack understanding of population genetics—the essence of microevolution. Sure, they may be taught that bacteria evolve drug resistance but do they really understand why this is called evolution and how it relates to the big picture view of the history of life (macroevolution)?
It has not been much appreciated until now how deficient our textbooks and instructional materials are in explaining to students how we know what we know about macroevolution, the patterns and processes that describe the major changes in the history of life. There is no reason at all to develop this in textbooks so as to convince the 25% of our populace who are fundamentalist Christians of the reality of large-scale evolution. This effort is about the 40–50% of people in the middle, who are reasonable and uncommitted, but otherwise uneducated about the problem. If they are able to understand how we know what we know about macroevolution, creationists are further marginalized as irrational and unreasonable.
I believe that the best way to teach evolution in the 21st century is to begin with genetics and population genetics and make sure that students understand the minimal definition of evolution. This is how we learn evolutionary theory and this is how we make sense of the rest of biology, including the fossil record. It's not good enough in this day and age to simply point to a fossil record—like the transitional fossils leading to modern whales—and say that this is "descent with modification." We have a pretty good idea how that process actually occurred; it involved speciation events and changes in the allele frequencies within populations. So why not teach that?
... it's important to appreciate that natural selection isn't the only process of evolutionary change. Most biologists define evolution as a change in the proportion of alleles (different form of a gene) in a population.
Jerry Coyne in Why Evolution Is True (page 122)Now let's look more closely at the 2013 article by Kevin Padian. This is the one where he discusses misrepresentations of evolution in textbooks. He discusses a whole bunch of problems but he doesn't once mention that textbooks—other than evolutionary biology textbooks— are extremely adaptationist in their presentation of evolution. It's pretty clear from his article that Kevin Padian doesn't think about any mechanisms of evolution other than natural selection (and sexual selection). Because he's an adaptationist, he doesn't see that problem.
I'm just going to discuss his view of the definition of evolution to illustrate the way Kevin Padian's view of evolution differs from mine. Kevin says,
... how does one choose a definition of evolution to use? Because science has no catechisms, there is not a single, standard definition of evolution. But some are more and less useful. A popular one, especially among scientists who work on population biology, is ‘a change in gene frequency in a population’. This means, for example, that an allele with a frequency of 0.75 in one generation can change to 0.73 in the next, and this is evolution. Well, sort of. In the next generation, the frequency can change back to 0.75. So what has evolved? It is like defining a football game as the process of hiking the ball. This simple (or simplistic) definition gets to one level of the processes of evolution (yet it misses many processes from speciation to what causes changes in gene frequencies in populations). Other definitions, such as ‘the history of life’, get to the patterns of evolution, but do not describe their causes. So both kinds of definitions are inadequate on their own.Most population-based definitions of evolution include the idea that the changes in allele frequencies have to occur over many generations. This is to avoid the very trivialization that Kevin mentions. When you teach a course on evolution you start by explaining how changing allele frequencies will (almost) inevitably lead to fixation of one allele and elimination of another. Then you teach that there are several mechanisms that can cause this. The most important mechanisms leading to fixation of alleles in a population are random genetic drift and natural selection.
There's a good reason why you don't include the explanation (mechanism) of allele frequency change in the definition of evolution. It's because there are many possibilities and we don't know for sure that we have discovered all of them [What Is Evolution?]. Kevin's other complaint, that the minimal definition doesn't include other important parts of evolution, such as the splitting of population (cladogenesis), is quite valid. That's a higher level process that we can teach once students have mastered the basic population genetics concepts of natural selection, random genetic drift, population size etc.
Kevin thinks there's a better way ...
Darwin’s definition, which he used in On the Origin of Species, was ‘descent with modification’. Although it may seem at first glance simplistic or vague, it embodies both the patterns of evolution (descent) and its processes (modification). It is as useful on a short timescale as on a long one; it suggests minor evolutionary modifications as well as major ones. In the last paragraph of Chapter 6 of the Origin, Darwin used this simple definition to settle a century of debate about what controls the morphology of form in the first place (Figure 1). Geoffroy St.-Hilaire and others had stressed ‘unity of type’, the features that characterize major groups of animals (mollusks, arthropods, vertebrates) and seperated them from others. Baron Georges Cuvier had emphasized ‘conditions of existence’, circumstances that made it advantageous for herbivorous animals to have cropping teeth, complex guts, and hooves for fleet escape. Darwin brushed away this conflict in a single paragraph by showing that common descent could explain the common body plans of related organisms, and that natural selection could explain their adaptive differences as they were modified to fit the conditions of existence.There's a reason why most of us think that "descent with modification" is "simplistic or vague." That's because it IS simplistic and vague.
That definition doesn't include the basic concept that it is populations that evolve and it doesn't include the basic concept that the changes have to be due to changes in the genes. Darwin didn't know about genetics and population genetics but we do. It is not a misrepresentation for textbooks to define and teach evolution from a population genetics perspective. We know so much more that Darwin did in 1859.
It's troubling that a leading evolutionary biologist and President of NCSE has a view of evolution that is strictly adaptationist, and opposed to population genetics as a core concept in teaching evolution.
Thompson, J.N. (2007) Use the word evolution. Evolution: Education and Outreach 1:42-43. [PDF]
Padian, K. (2010) How to Win the Evolution War: Teach Macroevolution! Evolution: Education and Outreach 3:206-214 [doi: 10.1007/s12052-010-0213-5]
Padian, K. (2013) Correcting some common misrepresentations of
evolution in textbooks and the media. Evolution: Education and Outreach 6:11 (published online June 25, 2013) [doi: 10.1186/1936-6434-6-11]