The stated aim of Nature’s Compass is to provide an update on the scientific subject of navigation because “the last serious review for the well-read non-specialist audience is more than two decades old” (p. xi). You could read this book just for enjoyment (a “light read”), and it would be fascinating. But a lot of the interesting, complex information would almost immediately be forgotten because there is not a lot of repetition or emphasizing of main points – this is not a textbook. The authors’ tone reads as a friendly conversation among highly educated people, not simple or overly repetitious. It is up to you to decide the highlights for your particular purpose. If your mind wanders, you can follow the conversation, but you long for the interesting details you missed. The wonderful thing about a book, however, is that you can back up and reread sections.
The authors examine time sense and the multiple circuits used by animals, as well as time-independent work-arounds, recalibration techniques, and synchronizations. Then the authors turn to compasses, how time and compass combine with memory to permit piloting and inertial navigation, map sense, and the threats posed by humans to species that rely on navigation. “The twin threats of habitat loss and climate destabilization [over the past 25 years] lead many researchers to ask whether the elegant programing that enables migration might now be leading migrating animals into oblivion” (p. xi). The authors italicize the most important basic scientific terms and then define them and give examples (e.g., “Zooplankton, the minute drifting organisms in the sea that ultimately feed nearly all of the ocean’s fish” [p. 11]). Bolded subheadings divide the chapters, and the figure legends are clear and comprehensive. The diagrams are simple (all black and white, mostly line drawings) but effective, even for complex topics. There are no pictures of the organisms, but these are largely unnecessary as the authors focus on a subset of well-studied species: honey bees and homing pigeons (their own research organisms), sea turtles, and migratory birds. But many other species are woven in, including other insects, Bermuda fireworms, spiny lobsters, whales, mice, terrestrial flatworms, and even bacteria. They cover different habitats (the sky, ocean, and land) and spatial scales (from very short distances to across the planet), and a range of orientation strategies from simple to astonishing.
In terms of using the book as a reference guide, there is an index in the back. The layout of the chapters is according to types of navigational strategies; the focal species are mentioned in multiple chapters rather than in separate animal-specific chapters. To understand how a particular animal navigates, the reader needs to maintain her attention through more than a few pages (I found taking notes to be helpful). This format makes it harder to understand what processes a bee is using and so minimizes the use of this book for people interested in specific animals, but it provides a better overall understanding of general navigation (the stated goal of the book) and fodder for comparative approaches. Each chapter has an affiliated reference list containing both classic and recent papers. The preponderance of titles is pre-2000. The titles (mostly primary scientific literature articles, with excerpts from some science books) are arranged alphabetically rather than chronologically, so determining the most recent references takes a bit of effort. Unfortunately, there are no in-text reference citations guiding you as to which references would be appropriate for particular points.
Nature’s Compass begins with the sinking of the 300-ton Portuguese merchant ship San Antonio in 1621. After this gripping beginning, the authors come back to that example again and again, adding new bits of information to compare human navigation strategies with those of other animals. “Humans too come into the narrative, though often as an example of what not to do” in terms of navigation (p. xi), as “humans have developed clumsy ad hoc strategies for navigating, and we will use these as models to understand what animals are doing with far greater ease and elegance” (p. 16). While this implies that the book will bash humans and laud animals from some utopian viewpoint, in reality the two are meshed much better and humans also seem interesting, albeit limited, compared with the other species. The book is peppered with interesting historical bits that augment the science and make snippets snag in your mind.
The amount of unanswered questions about navigation is surprising, considering how long this topic has been recognized as important. The authors concede what is known and what still awaits explanation, where research has been particularly challenging or is still incomplete. “Orientation and migration are conundrums that have been only haltingly solved. The challenge has been difficult because mechanisms vary not only between species, but within the same animal in different contexts and at different ages. Creatures are using the sun and stars, polarized light and color gradients, endogenous timers (daily, tidal, lunar and annual), landmark memory and cognitive maps, magnetic fields, extrapolated gradients, and more. They confound study by using cues redundantly, so that if we remove one source of information they simply switch to a back-up, making a shambles of our attempts to understand their abilities” (p. x). The authors point out that often the reason for slow progress in a field is the limitations of humans to concede that animals may be able to sense things differently, and perhaps more effectively, than we can. “We are guilty of condescending anthropomorphism, reading into other orders of beings our own blindnesses and computational limitations. Selection seems to have led to a variety of solutions to the challenge of finding home or other goals, recruiting sensory systems unknown to science before the navigational behavior of bees and pigeons led us to the discovery of such systems” (p. 33). I found the candor of the authors and their evident love for this subject and its intersection with human history fascinating and vitalizing.
ELIZABETH COWLES teaches sophmore-level biology, biochemistry, and entomology at Eastern Connecticut State University. She has taught at the undergraduate and graduate college levels for over 20 years. Her interests include insect toxicology, protein characterization, and astrobiology. Cowles holds degrees in biology and biochemistry from Cornell University and Michigan State University. Her address is Department of Biology, ECSU, 83 Windham St., Willimantic, CT 06226; e-mail: email@example.com.