| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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reviews The Minds of Birds, by Alexander F. Skutch with illustrations by Dana Gardner. Texas A&M University Press, College Station, Texas, 1996, 183 pp., $29.95 cloth. Alexander Skutch is the dean of neotropical ornithological studies. His many detailed life histories of birds of the New World Tropics, published as monographs and research papers in ornithological journals, have catalyzed untold numbers of scientific studies by graduate students and professional scientists throughout the world. Skutch is also author of a number of science books for the lay public. In the latest of these, The Minds of Birds, he draws from the published literature and his six decades of observation to argue that birds are conscious beings with mental capacities that have been grossly underestimated. He notes that birds are capable of recognizing individuals: parents, young, and flock mates. They can even recognize individual human beings; scientists working with crows and jackdaws soon learn that sentinels will recognize an investigator from far away and warn their comrades with alarm calls. Donning clothes unfamiliar to the crows enables an investigator to approach unrecognized. Skutch argues that birds have the capacity for enjoyment. They certainly play. Common ravens often play roll in flight, "because they enjoy the exercise," Skutch says. One raven rolled nineteen times during a continuous performance. Birds are capable of counting, either by tapping their bill or, as in one parrot, vocalizing numbers in English. Various unrelated species of birds, such as killdeer or mourning doves, will feign injury to lure predators away from their nest. They keep just far enough ahead of the potential predator to avoid being caught. Skutch notes that "whether they are aware that they are using deception is not known; but numerous observations leave no doubt that they are in full control of their movements and aware of what they do." Birds share our five senses; however, some birds have been shown to be sensitive also to the Earth's magnetic field. For example, homing pigeons fitted with a Helmholz coil, which can twist the Earth's magnetic field to the right or left, will fly to the right or left of the direction of home when released. Control pigeons fitted with Helmholz coils with dead batteries will fly straight home. During migration and homing, birds are sensitive to the Earth's magnetic field but are also sensitive to the position of the sun and stars in the sky in orienting themselves. The final chapter, titled "The Mind of a Parrot," is devoted almost entirely to Alex the gray parrot. This remarkable bird is the subject of many studies by Irene Pepperberg and her students at the University of Arizona. Alex uses English words to label some 100 objects, shapes, and colors. He can also combine concepts such as "green wood." I visited Alex in Tucson last year and observed him labeling a few English "letters" and vocalizing at least six phonemes which he read from plastic letters arranged on a board. Skutch's book is a fascinating compilation of anecdotes. But are animals really consciously aware and capable of cognition as Skutch implies? Although Skutch's arguments are persuasive, the book does not "prove" consciousness in a scientific sense. Anecdotes, however, especially if they are careful natural history observations, may provide the raw materials for hypothesis testing, and thus should never be dismissed. If direct evidence of another's "consciousness" is attainable, such proof will remain elusive for a long time. Cognitive processes in animals (and perhaps humans) cannot be assessed directly, but can only be inferred from various behavioral responses measured in experimental situations. Through these indirect means, we may also seek in the animals some of the attributes of cognition that we have traditionally considered uniquely human, including memory and selective attention, categorization, information processing, and decision making. A white-crowned sparrow, for example, learns the song (dialect) of the region where it settles by interacting with the local territory holders. It memorizes one of these songs and will often vocalize it during territorial conflicts or when advertising for a mate. However, white-crowns store more songs in memory than they produce. By playing tape- recorded songs of neighbors versus white-crowns from a different neighborhood, it has been shown that the birds will respond more aggressively to strange songs than to familiar ones. It would be energetically expensive and dangerous for a white-crown to attack every other sparrow it hears. A white-crown must thus make a decision to sing back, ignore, or attack. It usually ignores the neighbor who is already familiar with the territorial boundary, or gives a single loud song, enough to remind him to keep his distance. A stranger, on the other hand, is often chased off as he doesn't know the local situation and may venture into the territory to steal food or to copulate with one's mate. (Frequently, intruders sneak in: blood protein studies have revealed that close to 40 percent of white-crowned sparrows hatched at Tioga Pass outside Yosemite National Park are products of extra-pair copulation.) The bird's ability to "memorize" and "categorize" is revealed when it distinguishes songs of all its neighbors from strangers. "Information processing" and "decision making" have also been demonstrated by the nature of the bird's response to songs of strangers versus neighbors, which it may recognize by both appearance and voice. Skutch has written this book in a style that is attractive and relatively free of scientific jargon. However, he is acutely aware of the principles of cognition. He tells us that "Birds' minds evolved to adjust innate behavior to the variables of heterogeneous environments. Since conscious awareness should increase their effectiveness, it is reasonable to believe that evolution would sharpen it." In discussing distraction displays he reminds us that "They appear free to perform or not to perform, as they please." They make decisions! Darwin believed that the difference between our minds and those of "lower" creatures is not absolute, but a continuum. Skutch's book will remind us that the distance between ourselves and the other creatures that share our planet is not as large as we once thought. He summarizes some of the experiments that support this view, and concludes with the hope that: "It should also encourage us to intensify our struggle to save an overpopulated, overexploited planet from impending disaster, and especially to protect the birds, whose minds are among nature's greatest wonders." From Lucy to Language, by Donald Johanson and Blake Edgar, principal photography by David Brill. A Peter N. Nevraumont Book/ Simon & Schuster Editions, New York, 1996, 272 pp., $50.00 cloth. It is very rare in the sciences for one book to serve well the interests of the scientific community and the lay public. Books on human evolution tend to be either dry, sparsely illustrated, and thickly referenced academic tomes aimed at the specialist, or superficial treatments that abound in line drawings and reconstructions of dubious quality.From Lucy to Language is one conspicuous and wonderful exception to this rule. It serves scientists by providing concise descriptions of the primary fossil evidence of human evolution that are accompanied by impeccable, life-sized photographs of individual fossil specimens. It serves the lay public by providing the most readable and visually engaging introduction to human evolution published to date. Part One is devoted to the central issues of paleoanthropology. Here, under 48 topic headings, we find concise discussions of themes ranging from the kinds of evidence used to unravel information on ancient humans and their environments, to the nature of Pleistocene pregnancies and the emergence of art and language. This section is graced by a series of David Brill's arresting photographs of the skulls of various modern human populations that provide an excellent basis for comparison with the fossil materials presented later in the book. The second and longer section of the book, "Encountering the Evidence," is devoted to a detailed presentation of the fossil evidence for human evolution. Over- views of the widely recognized genera of fossil hominids are followed by descriptions of the major specimens known today presented in order from the oldest to the youngest. Photographs of extraordinary clarity allow one to investigate the specimens as closely as one might do in person. The color, texture, and anatomical details have been captured with an unprecedented accuracy. The one-page descriptions of the fossils are replete with useful information. The top of each description page bears a header giving the basic data on the specimen and the citation of the scientific paper in which it was first described. There follows a concise account of the circumstances of the fossil's discovery and salient information on its important features and overall significance. These descriptions manage to convey copious, detailed information on the fossils, while providing insightful and sometimes poignant views of the people who first discovered and described them. This section concludes with a short, illustrated review of Paleolithic technology. For the inquiring student or scholar, the value of the book is enhanced considerably by the inclusion of a list of type specimens for hominid species, a map of major hominid fossil sites, and a list of selected references. From Lucy to Language is a book that you will want to revisit often, and one that you will want to share with your children and friends. I, along with many of my colleagues in paleoanthropology, recall that F. Clark Howell's popular book, Early Man, kindled our imaginations and set us on a path to investigating the wonders of human evolution. Johanson and Edgar's beautiful book now takes its place as one which will inspire future generations who will fill this niche. It is a family album for all of us. My copy is already dog-eared. Recommended Reading From the
Editors' Desks
Shurtleff's Sonoma ranch, where a colony of "self- introduced" feral mandarins live alongside a natural population of wood ducks, serves as backdrop for much of the book. There Shurtleff has observed and aided the mandarin's settlement for the last 25 years. Savage, former chairman of the World Pheasant Association and of the International Trust for Nature Conservation, has been studying and writing about the mandarin for over 40 years. Together they have created a book both personal and thorough; like the birds that are their passions, that is a rare and wonderful combination. Testimony: Writers of the West Speak on Behalf of Utah Wilderness, compiled by Stephen Trimble and Terry Tempest Williams. Milkweed Editions, Minneapolis, Minnesota, 1996, 120 pp., $6.95 paper. As Bill Clinton signed legislation in September to create a national monument encompassing nearly two million acres of Utah canyonlands, writer Terry Tempest Williams presented to the President, Vice President Gore, and Interior Secretary Babbitt, copies of this eloquent chapbook of essays, poems, and observations. Testimony had previously been given to every U.S. senator in hopes of swaying a contentious debate over whether this land would remain untrammeled. Part of the "Literature for a Land Ethic" series from nonprofit Milkweed Editions, Testimony showcases the donated work of 21 writers who have walked Utah's redrock and can speak to its stark beauty. Contributors include Williams, John McPhee, Gary Nabhan, Barry Lopez, Rick Bass, Ann Zwinger, and N. Scott Momaday. Collectively, these writers affirm that, in William Kittredge's words, "We have nowhere to live except in nature.... Lose contact with that which is wild and we fall out of touch with all that this animal we are is able to understand as actual." Besides persuasive prose, the book contains a map of Utah redrock wilderness plus a list and map of U.S. wilderness areas. Sales proceeds will benefit the Utah Wilderness Coalition. |
Spring 1997
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