Attention to Evolution in Textbooks Decreasing, Study Says
A "significant" decline in the emphasis on evolution in high-school biology textbooks that began in the 1970's has continued so far in this decade, according to a researcher who has completed a study of how much space is devoted to evolution in 102 textbooks published between 1900 and 1982.
Gerald Skoog, chairman of the secondary education department in the college of education at Texas Tech University, says the decline is due largely to the response of publishers to a resurgence of "anti-evolutionist" feeling in the country.
"Some of the content that has been removed or shortened is a result of needed editing of textbooks that were written by committees," Mr. Skoog said. "However, it seems clear that the ... recent de-emphasis of the coverage of evolution in the textbooks [is] mostly a result of the strenuous pressures anti-evolutionists have exerted upon publishers, authors, educators, and policymakers."
One publisher involved in producing science textbooks who did not wish to be named maintained that assessing the relative importance given to evolution in textbooks based strictly on word counts is an illogical and inefficient method.
The subject has received increased attention in recent years because of the growing support for creationism at the state and local level. Evolutionists have been stepping up their efforts to fight creationism in state cases such as the Arkansas creationismrial held last year and before local school boards that are being asked to weigh the relative merits of creationism and evolution.
Last summer, the role that textbooks play in the debate came into focus when a committee for the New York City schools rejected three textbooks for inadequately treating the subject of evolution.
Jerry Resnick, president of the National Association of Biology Teachers (nabt) and a member of the New York committee, said he has "absolutely" observed a decrease in emphasis on--and number of pages devoted to--evolution.
"Publishers won't openly say they have reduced the number of pages but all you need to do is check," Mr. Resnick said.
Mr. Skoog discussed his results last week at the nabt's annual meeting in Detroit during one of several sessions devoted to the topic of evolution and creationism.
Mr. Skoog and others, including nabt's executive director, Wayne A. Moyer, believe that textbooks are the best indicators of what is being taught in the classroom. "For most high-school teachers, the textbook is the curriculum," Mr. Moyer said.
Over the past several years, Mr. Skoog has counted the words devoted to each of 44 topics related to evolution in selected high-school biology textbooks. And he has traced the changes that have occurred in the treatment of those topics in successive editions of the texts.
Of his sample, Mr. Skoog writes, "No claim has been made that the sample of textbooks in this study includes all of the best sellers of this century."
But the researcher said last week that his study did include "most of the most popular textbooks" that have been used, as well as selections that were representative of the various choices available to teachers.
Of the 102 textbooks he examined, ac-cording to Mr. Skoog, 85 had specific chapters on evolution. In 53 of these, evolution was covered within the final quarter of the textbook. Often, Mr. Skoog said, teachers do not work through the entire text during the year.
"Creationism" or "catastrophism" (generally, the idea that the earth was created in a short time by a supernatural being) was included in nine of the 102 books. Six of the books including this topic were published after 1970, Mr. Skoog said.
Mr. Skoog found rising and falling attention to evolution in textbooks over the 81-year period he studied.
Prior to 1960, he said, textbooks' coverage of evolution was "brief, noncontroversial, and characterized by restraint," although he did find a continued increase in emphasis on evolution from 1900 to 1950.
In the 1950's, statements emphasizing evolution became less frequent in some books. The word "evolution" did not appear in eight of 14 textbooks Mr. Skoog examined for that decade.
Some statements about evolution were "toned down," he said, citing as an example the difference between statements on evolution in a 1938 biology textbook and those in the 1954 edition of the same book.
The first read: "Plants and animals have been changing and are now changing. No one acquainted with the facts doubts that evolution, or continued change in plants and animals, has taken place. No one has discovered a single fact to disprove the theory of evolution, and facts that establish it are abundant."
He compared this to the later edition's statement on evolution: "Biologists agree today that plants and animals have changed in the past, and continue to change."
During the 1960's--due largely to the appearance of textbooks produced by the Biological Sciences Curriculum Study (bscs) in Colorado, the country's largest developer of biology texts and curriculum materials and an avowedly pro-evolution group--space devoted to evolution increased dramatically as measured by Mr. Skoog.
bscs textbooks have treated evolution much more thoroughly than have other books, Mr. Skoog asserts. The 16 bscs textbooks published since 1961 have included 39 percent of the approximately one million words on evolution and related topics in the 102 books he examined between 1900 and 1982, Mr. Skoog said.
In the 1970's, the overall coverage of evolution in biology textbooks was reduced, Mr. Skoog said, a pattern that has continued in the 1980's.
In addition to the decline in the total number of words devoted to evolution, the researcher pointed out, "word changes in the textbooks of the 70's resulted in many statements becoming less definite, more cautious, and thus less controversial than those appearing in earlier editions."
His latest work reveals a "continued erosion" in emphasis on evolution in the 1980's, he said.
"One biology textbook, published in 1981, did not use the word evolution or have a specific chapter on evolution. Material concerned with evolution was scattered throughout," Mr. Skoog said.
"Statements indicating that biologists support the validity of evolution have become very modest and almost nonexistent in textbooks published since 1980," he added.
Even the pro-evolution bscs books, he said, now devote less space to the subject that they did in the 1960's.
William V. Mayer, now president emeritus of bscs and a witness for the American Civil Liberties Union in last year's Arkansas creationism trial, said, "In our particular case, it doesn't have anything to do with outside pressures.
"The problem is one of space," he explained. "Textbooks run between 500 and 800 pages and ours are at the upper limit. When you get new materials you can't make the book bigger. All of the new material on human genetics, for example, had to have space made for it."