Evolution Education: What a Difference a Dozen Years Makes!

Glenn Branch

A lot can happen in twelve years—even in evolution. It took just a dozen years for a population of threespine stickleback fish to evolve to lose the bulk of their armor after colonizing a freshwater lake in Alaska (Bell et al. 2004). Experimental populations of a species of wheat managed in the same amount of time to evolve flowering schedules adapted to different climates in Europe (Rhoné et al. 2010). And over 25,000 generations of E. coli evolved and were monitored in exquisite detail in Richard E. Lenski’s Long-Term Experimental Evolution Project over the course of its first twelve years (Blount et al. 2008).

It turns out that a lot can happen in twelve years in evolution education too. In a recent report published in the peer-reviewed journal Evolution: Education and Outreach, Eric Plutzer, Ann Reid, and I discuss the results of a rigorous national survey of public high school biology teachers commissioned by the National Center for Science Education (Plutzer et al. 2020). The survey, conducted in 2019, was designed to replicate a similar national survey conducted by Plutzer and his colleagues in 2007 (Berkman et al. 2008). There was a lot of change in the twelve years between the two surveys—and a lot of it was for the better.

For starters, the teachers reported teaching more evolution. In 2007, the average number of hours devoted to teaching evolution in general was 9.8 hours, with human evolution in particular receiving 4.1 hours. In 2019, the average number of hours devoted to teaching evolution was up to 12.4 hours, a rise of 25 percent, with human evolution in particular receiving 7.7 hours, a rise of 90 percent. Because “nothing makes sense in biology except in the light of evolution,” as Theodosius Dobzhansky (1973) famously explained, the increase suggests a degree of progress in high school biology classrooms.

But it wouldn’t be true progress unless the increased discussion of evolution was scientifically accurate. What were the teachers saying about evolution? In both surveys, teachers were asked to answer a handful of questions about what themes they highlighted to students in their classes, including whether they emphasize the broad scientific consensus on evolution, whether they emphasize that creationism is a valid scientific alternative to evolution, and (to test a hypothesis about appeals to authority) whether they emphasize that there are reputable scientists who regard creationism as a valid scientific alternative to evolution. 

Based on their answers to these three questions, the report offered a fourfold typology of teachers. For the sake of concreteness as well as mnemonic convenience, think of them as Eve, Avery, Mimi, and Craig. Eve emphasizes the broad scientific consensus on evolution while not giving any credence to creationism. Avery avoids endorsing evolution or creationism, while Mimi sends a mixed message by endorsing evolution but also endorsing creationism as a valid scientific alternative to evolution. And Craig, unfortunately, endorses creationism while not endorsing (and perhaps even disputing) evolution.

In 2007, Eves were in the majority, but only barely so, at 51 percent. By 2019, there was a dramatic shift, with more than two-thirds of public high school biology teachers—67 percent, to be exact—reporting as Eves. The proportion of Averys, Mimis, and Craigs correspondingly decreased over those twelve years: from 18 to 15 percent for Averys, from 23 to 12 percent for Mimis, and from 8.6 to 5.6 percent for Craigs. With about four million students enrolled in high school biology classes in the public school system in any given year, the gains for accurate, complete, and honest evolution education are clearly enormous.

It is still a matter of concern that so many of these teachers—more than one in six, 17.6 percent—are presenting creationism as scientifically credible. Unsurprisingly, the personal religious beliefs of teachers play a large role in their choice of what themes to emphasize in the classroom. Presented with the standard options used by Gallup in its polling on evolution and creationism, 4 percent of Eves, 12 percent of Mimis, 25 percent of Averys, and a whopping 60 percent of Craigs in 2019 agreed with the creationist option, “God created human beings pretty much in their present form at one time within the last 10,000 years or so.”

Even here there is encouraging news. In the 2007 survey, 16 percent of all the teachers surveyed agreed with the creationist option when presented with the Gallup question, while in the 2019 survey, only 10.5 percent—and only 7 percent of the younger teachers who began teaching after 2007—did, suggesting that creationists are decreasingly likely to be represented among public high school biology teachers. The decrease among high school biology teachers significantly outpaces the decrease in creationism among the general public, which fell from 46 percent in 2007 to 40 percent in 2019, according to Gallup (Brenan 2019).

What accounts for such a striking improvement in the emphasis on evolution in the high school biology classroom? Part of the explanation involves the Next Generation Science Standards (NGSS Lead States 2013), the model set of state science education standards introduced in 2013, endorsed by the National Science Teaching Association (National Science Teaching Association 2016), and adopted in twenty states (plus the District of Columbia) so far. Evolution features prominently in the NGSS, which include “Biological Evolution: Unity and Diversity” as a so-called disciplinary core idea of the life sciences.

Judging from the results of the 2007 survey, the states that would later adopt the NGSS were not noticeably more hospitable to evolution education than states that would not. In fact, such states had the lowest proportion of Eves (49.7 percent) and the highest proportion of Mimis (26.7 percent), although they also boasted the lowest proportion of Craigs (6.3 percent). According to the 2019 survey, however, the states that had by then adopted the NGSS had the highest proportion of Eves (68.9 percent) as well as the lowest proportion of Mimis (11.6 percent) and Craigs (5.1 percent).

A degree of improvement was visible also in the two dozen states that adopted standards based on the same framework on which the NGSS is based (National Research Council 2012) as well as in the six remaining states (Florida, Ohio, North Carolina, Pennsylvania, Texas, and Virginia), so the NGSS is not exclusively to thank. But the evidence suggests that states that adopted standards with increased demands regarding evolution took steps to ensure that teachers acquired the content knowledge of evolution they needed to live up to those demands.

So along with the good news about the improvement in evolution education from 2007 to 2019, a moral emerges: substantial improvements in science education, even for a socially contentious topic such as evolution, are attainable by adopting a scientifically accurate and pedagogically appropriate set of state science standards and arranging to equip teachers with the wherewithal to ensure their students gain the knowledge and abilities specified by those standards. Clear and convincing gains for evolution education were so produced in just twelve years. What good news will a further dozen years of effort bring?



  • Bell, Michael A., Windsor E. Aguirre, and Nathaniel J. Buck. 2004. Twelve years of contemporary armor evolution in a threespine stickleback population. Evolution 58(4): 814–824.
  • Berkman, Michael B., Julianna Sandell Pacheco, and Eric Plutzer. 2008. Evolution and creationism in America’s classrooms: A national portrait. PLoS Biology 6(5).
  • Blount, Zachary D., Christina Z. Borland, and Richard E. Lenski. 2008. Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli. Proceedings of the National Academy of Sciences USA 105(23): 7899–7906.
  • Brenan, Megan. 2019. 40% of Americans believe in creationism. Gallup (July 26). Available online at https://news.gallup.com/poll/261680/americans-believe-creationism.aspx.
  • Dobzhansky, Theodosius. 1973. Nothing in biology makes sense except in the light of evolution. The American Biology Teacher 35(3): 125–129.
  • National Research Council. 2012. A Framework for K–12 Science Education: Practices, Crosscutting Concepts, and Core Ideas. Washington, D.C.: The National Academies Press.
  • National Science Teaching Association. 2016. NSTA position statement: The Next Generation Science Standards. Available online at http://static.nsta.org/pdfs/PositionStatement_NGSS.pdf.
  • NGSS Lead States. 2013. Next Generation Science Standards: For States, By States. Washington, D.C.: The National Academies Press.
  • Plutzer, Eric, Glenn Branch, and Ann Reid. 2020. Teaching evolution in U.S. public schools: A continuing challenge. Evolution: Education and Outreach 13(14).
  • Rhoné, Bénédicte, Renaud Vitalis, Isabelle Goldringer, et al. 2010. Evolution of flowering time in experimental wheat populations: A comprehensive approach to detect genetic signatures of natural selection. Evolution 64(7): 2110–2125.

Glenn Branch

Glenn Branch is deputy director of the National Center for Science Education, a nonprofit organization that defends the teaching of evolution and climate science. He is the coeditor, with Eugenie C. Scott, of Not in Our Classrooms: Why Intelligent Design is Wrong for Our Schools (Beacon Press, 2006).