January 16, 2020


Life on Earth: The Story of Evolution. By Steve Jenkins. Houghton Mifflin Harcourt. $7.99.

     Steve Jenkins is one of a very few authors who can create nonfiction for young readers that is every bit as captivating as fiction – a blend of teachable moments and attractive visuals that both catches the eye and informs the brain. Life on Earth, originally published in 2002 and now available in paperback, is an excellent example of Jenkins’ skill both with words and with illustrations cleverly made from cut and torn paper. The book is an introduction to the principles of evolution, one of the greatest and most thoroughly researched and accepted of all scientific principles. There is really no doubt that evolution is what drives speciation, although there remain small minorities that continue to deny its existence – largely because they deem it “only a theory,” which means they thoroughly misunderstand what a “theory” is in science (it is not a guess or hypothesis but as close to a fact as it is possible to come, given that scientists always look beyond current knowledge to modify and expand whatever is currently known).

     To draw young readers into a basic explanation of evolution, Jenkins starts with the remarkable comment that all life, from cacti to bumblebees to penguins, is descended from single-celled organisms that lived in a past so distant as to be quite literally unimaginable. Jenkins takes readers through the varying epochs of Earth’s existence, from the time before life all the way to today, showing a wide variety of living things from each time period – some bizarre in appearance and some closely resembling the flora and fauna of today. Then, about half-way through this thin but information-packed book, Jenkins asks the why question: “Why have so any different forms of life developed on the earth?” And that leads into an explanation of the way most people viewed the world before Charles Darwin’s time, and the discoveries and analyses that led Darwin to formulate the scientific theory of evolution. This part of Life on Earth is splendidly done, simplifying but not oversimplifying Darwin’s findings and illustrating them to perfection. First, Jenkins’ portrayals of the beaks of four finches from the Galápagos Islands show quite clearly how the similar-appearing birds’ differing beaks are adapted to take advantage of disparate food sources. Second, Jenkins shows “natural selection at work” by starting with an animal that young readers will know, a frog, and explaining how the mother frog’s 3,000 eggs lead to only 10 tadpoles that live long enough to become frogs and only two frogs that survive long enough to reproduce. It is the why of these two frogs’ survival that provides a key to evolution, as Jenkins explains carefully and with matter-of-fact elegance.

     Then Jenkins both tells and shows the workings of genetics, illustrating with admirable clarity the way in which variation (natural differences between parents and offspring) and mutation (the emergence of unexpected and unpredictable new features) lead, together, to creatures that are either more or less likely to survive and pass on their own characteristics. And he does a fine job of showing some of the effects of evolution, providing two full pages of pictures of beetles (which have evolved new shapes and sizes to fill differing ecological niches), followed by two pages showing animals that fit their habitats so well that they have remained essentially unchanged for hundreds of millions of years (turtles, horseshoe crabs, sharks and more). After a short explanation of extinctions – whose effect on evolution is massive but would require another book to explain with even a modicum of detail – Jenkins returns to where he started Life on Earth, this time showing the progression of life as if Earth’s entire existence could be compressed into a single day. The idea is to help young readers grasp the immense time span over which life has developed and changed by relating Earth’s history to a time period with which readers are familiar. This is only moderately successful – the human brain simply cannot grasp a time period of billions of years – but it is as good an attempt as anyone else has made to engage readers’ interest and thinking about the way life on our planet has evolved. Life on Earth is an excellent introduction to its topic and a book that is fascinating enough to read again and again, even as it will likely encourage many young readers to go elsewhere for more-detailed information on the evolution of plants and animals.

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