It’s the longest field trip ever for Ms. Frizzle’s class! In the latest installment in the popular Magic School Bus series, a classroom activity involving the construction of family trees leads to a 3.5-billion-year excursion, tracing the human lineage from the primordial cell through the first vertebrates to mammals, primates, hominins, and, finally, Homo sapiens. “We may speak different languages, eat different food, make different art, and have different religions,” Ms. Frizzle observes toward the end of the journey. “But we are all human beings with the same family tree” (p. 45). (The message is reinforced by the inclusion on the field trip of a cousin of one of the students, visiting from China.) The students then work together to construct a “terrific”—and charming, if selective—phylogenetic chart.The approach of beginning with the familiar idea of a family tree and then introducing the idea of common ancestry is ideal for the intended readers, four through eight years old. The focus on following the human lineage is likely to reinforce the misconception that evolution is intrinsically progressive, which the occasional digression to highlight different lineages is not likely to be able to dispel, but the advantages outweigh the disadvantages. As in the Magic School Bus series in general, the pages (attractively illustrated by Bruce Degen) teem with corny jokes both verbal and visual, informative sidebars, and cameo appearances that invite further exploration—paleontology aficionados will particularly relish the opportunity to tell young readers about Pikaia, Tiktaalik, and gorgonopsids.The last few pages abandon the narrative approach for straightforward exposition, and here especially the young reader will need further information and explanation from a well-informed mentor. (It would have been nice for there to be a guide for teachers and parents to prepare them for these discussions.) The exposition begins with a sketch of the evidence for evolution, including the fossil record and its documentation of evolutionary transitions, anatomical homology (misleadingly labeled “body plans”), embryological homology, a gesture in the direction of molecular homology, and vestigial and rudimentary structures. It is particularly gratifying to see a reminder “Evolution is still at work!” with a brief treatment of the medical and agricultural relevance of evolution.Then natural selection is presented with a fictitious but realistic example. (The example involves adaptive melanism in a population of mice living on white and black sand beaches; a well-documented example of adaptive melanism involves a population of rock pocket mice, Chaetodipus intermedius, living inland on light substrate and dark lava.) The example is vivid and helpful, although it is awkward that the inheritability of the mice’s coloration is not initially mentioned: the reader is told only, “After a while, almost all the mice were light,” without any indication that the shift is generational (p. 52). The oversight is rectified on the following page—“nature selects, or chooses, which living things survive to pass on their traits to their babies” (p. 53)—but then it is necessary to reread the previous discussion.The discussion of natural selection is presented under the heading “How Does Evolution Work?” as if natural selection were the only process at work in evolution, which is inconsistent (since endosymbiosis is described earlier in the book) and inaccurate: describing natural selection as important would have been preferable. In any case, the discussion of natural selection is followed by a discussion of artificial selection. The order of explanation thus inverts that of the Origin, which introduces natural selection by first describing artificial selection, with which Darwin’s original readers were presumably more or less familiar. With increased urbanization, Cole and Degen’s readers are not so likely to be acquainted with artificial selection, so the point of discussing it (at the same length as natural selection) is obscure.Given the continuing popularity of the Magic School Bus franchise—including not only the books but also a number of video games, two television series, and, reportedly, a planned big-screen version with Elizabeth Banks as the beloved teacher—the book is sure to end up in the hands of children across the country. Wahoo! (as Ms. Frizzle would say). Asked in 2019 by PBS Newshour why she and Degen wanted to write a book about evolution, Cole replied, “A famous scientist [Theodosius Dobzhansky, writing in The American Biology Teacher] once said, ‘Nothing in biology makes sense except in the light of evolution.’ That really means that evolution is the story of life on Earth.” For anyone wanting to share that story with young readers, The Magic School Bus Explores Human Evolution will be a splendid start.
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Sep 25, 2023
Yihe Zhang 
Open Access
