Scientific Answers to the Mysteries of Children's Literature AS parents of a young child, we are in the enviable position of reading a lot of beautifully drawn and smartly written short stories that fall under the moniker "children's books." And in doing so we have discovered one of the immutable truths of childhood: a book worth reading once is worth reading 17 times in a row. Sometime after the 10th reading of a particular book in a day we find ourselves examining the deeper and unspoken questions brought up by the text: Why is George so curious? Are Frog and Toad really friends? And most perplexing of all, what does Brown Bear actually see? Happily, science provides answers to such questions. Brown Bear, Brown Bear, What Do You See? The bright images of Eric Carle's books dot many a parent's living-room floor, but researchers might demur at his answer to "Brown Bear, Brown Bear, What Do You See?" In the story, the titular bear sees a red bird looking at me. According to research on mammalian vision, the brown bear is a dichromat, meaning that it has two types of cells in its eyes to determine color. Humans have three. A short-wave cone cell sends violet shades to his brain; a long-wave cone sends something in the yellow or green range. So although the bear would be able to view the colors of some of the later animals in the books, like the white dog and the yellow duck, his perception of a bird's redness is likely to be very weak. Brightness, more than color, would dominate the experience. What do you see, brown bear? A bird-shaped figure with some feathers brightly standing out from a generally drab body. Frog and Toad Are Friends The central theme of Arnold Lobel's 1970 classic of the anthropomorphic oeuvre is that these tailless amphibians are fast friends. But what about in the real world - are toads and frogs capable of such friendship? A 2009 paper in the research journal Oecologia examined what happened when cane toads were introduced into the environment of native frogs in Australia. Far from being an ecological disaster, there were some unexpected benefits for the frogs, although it came at a cost that might be better suited to a grisly Greek myth than a children's book. When frogs consumed toad eggs, which were toxic, both populations suffered; however, the frog tadpoles that survived grew bigger and healthier. In other words, the reason that Lobel did not create a scientifically accurate portrayal of frogs and toads is that the title would have been something on the order of "Frog Eats Toad's Poisonous Unborn Children, Gets Sick and Dies (but Frog's Younger Cousin Thrives!)." Curious George Careful readers of the Curious George canon may have found themselves bedeviled by a wide range of George-related questions: What kind of monkey is he? Who is this fellow in the yellow hat? And why is that monkey so curious, anyway? At least one of these queries may be answered by a paper published in 2010 in the Journal of Comparative Psychology, which examined the curiosity levels of spider monkeys and stumptail macaques. The macaques, which like George are tailless, scored high on a "curiosity index" when faced with oddities like organic paint and mealworms. Males were especially curious, but all macaques were less curious than the spider monkeys. The researchers speculate that this is because spider monkeys live in a society with lax social rules; without a rigid hierarchy and dominant individuals to control others" activities, animals are presumably more free to investigate, seek novelty and explore. Imagine if George had been a spider monkey! Instead of snatching hats, as he is wont to do, George would simply gaze at the man with the yellow hat and incessantly inquire, "Why is it yellow? Why do you wear it on your head? Don't Let the Pigeon Drive the Bus! Throughout Mo Willems's 2003 book, the reader is sternly instructed not to let one determined pigeon take the wheel of the bus when the driver takes a break. But the authors of a paper published online this year in Animal Cognition (and titled, in a refreshingly contrarian fashion, "Let the Pigeon Drive the Bus") disagreed with Mr. Willems's exhortation. The authors examined captive pigeons" ability to navigate the traveling-salesman problem, a classic computational puzzle that asks you to devise the shortest round-trip route that stops at each city once. Pigeons were tasked with finding the most efficient route between a handful of feeders holding yummy peas. While the results did not speak to the ability to keep up with a bus timetable, pigeons turn out to be highly skilled in planning efficient travel routes, an ability that is wanting in some human bus drivers. Lest clarity mar the magic of childhood, we will stop there, and be sure not to tell you where the sidewalk ends, where the wild things are and how the Grinch actually stole Christmas. Alexandra Horowitz is the author of "Inside of a Dog: What Dogs See, Smell and Know." Ammon Shea is the author of "The Phone Book: The Curious History of the Book That Everyone Uses But No One Reads."