YEAR IN REVIEW 1997: LIFE-SCIENCES: ZOOLOGY

ZOOLOGY: Entomology. Anne-Genevive Bagnres of the Laboratory for Neurobiology-Chemical Communication, Marseille, France, and colleagues reported on the way in which one species of paper wasp, Polistes atrimandibularis, which is incapable of building a nest or producing a worker caste, persists as an obligatory social parasite on a related host species, P. biglumis bimaculatus. Social insects characteristically produce chemical signatures that enable colony members to recognize each another. Annually in late June a fertile parasitic P. atrimandibularis queen searches for the nest of her host species. At that time the chemical signatures of the two species differ, with the cuticle of the parasite producing a family of hydrocarbons distinctive from the composition of hydrocarbons produced by the host. On colonizing the nest, however, the parasite ceases producing the distinguishing hydrocarbons, and a month later her signature, based on gas chromatography and mass spectrometry, is indistinguishable from that of the host queen. For the remainder of the colonial cycle before the emergence of adult wasps and mating in late summer, P. biglumis bimaculatus workers feed and care for parasite offspring as they do the offspring of their own species. The study demonstrated the versatility of the parasite in adjusting its chemical signature at a critical time in its colonial cycle and supported the idea that, in addition to a simple role as an enclosure and a barrier, the cuticle of insects functions as a true gland. Researchers used training techniques to explore the ability of honeybees to distinguish between symmetry and asymmetry, a critical skill for pollinators in that the symmetry of a flower may indicate its quality. Martin Giurfa, Birgit Eichmann, and Randolf Menzel of the Free University of Berlin presented bees with different stimuli designed to be distinguishable only on the basis of their bilateral symmetry or asymmetry. One group of bees was rewarded for selecting symmetrical patterns, the other for selecting asymmetrical ones. Afterward, both were presented with either symmetrical or asymmetrical patterns that they had not seen before. Individual performance was measured by means of a microphone apparatus, adjusted to detect the bee's flight noise. The investigators recorded how often a bee chose the novel symmetrical or asymmetrical patterns, how close the bee went, and how long it hovered. The results indicated that bees could easily be taught to favour either symmetrical or asymmetrical patterns and could transfer that learning to patterns not seen before. Although bees could be trained to prefer symmetrical or asymmetrical patterns, they showed a predisposition for symmetrical ones. Previous studies had shown that bees are attracted to symmetrical shapes, but the new study demonstrated that they recognize symmetry as a property and respond to it on the basis of their experience. Mary E.A. Whitehouse and Klaus Jaffe of Simn Bolvar University, Caracas, Venez., studied leaf-cutting ants of the species Atta laevigata to investigate two laws of combat strategy. The linear law proposes that a few good fighters are a better strategy than many poor fighters in a series of one-on-one conflicts. The square law holds that if all individuals are equally susceptible to attack, many poor fighters are better than a few good ones. During manipulative field experiments the investigators staged battles between ants from one colony and those of another or against vertebrate predators. The ants responded to vertebrate threats according to the linear law, by recruiting specialized soldier ants from their colony. On the other hand, their response to threats from other ant colonies followed the square law; they recruited large numbers of smaller individuals. Thus, leaf-cutting ants alter their mode of fighting according to the threat and follow the combat strategy law most effective for the situation. (ANNE R. GIBBONS) This updates the article insect1. ZOOLOGY: Ornithology. Scientists regarded birds' use of tools as mostly stereotyped and their manufacture of tools as involving only limited modification of material objects. In 1996 Gavin R. Hunt of Massey University, Palmerston North, N.Z., reported that to assist in capturing insect prey, New Caledonian crows make and use two different types of hook tools from twigs and one kind of stepped-cut tool from the barbed leaf of the pandanus tree. According to Hunt, these instances of tool manufacture by a bird species had three features new to tool use in nonhuman animals: a high degree of standardization, distinctly discrete tool types with a definite imposition of form in the shaping of the tool, and the use of hooks. During the course of human evolution, such features first appeared in stone and bone tool-using cultures only after the Lower Paleolithic Period (about 2.5 million to 200,000 years ago). The foraging success and habits of pelagic (open-ocean) seabirds were largely unknown. Using satellite transmitters attached to the birds in conjunction with recorders for measuring feeding times and the weight of ingested food, researchers found that wandering albatrosses on foraging trips from the nest encountered prey on average every 4.4 hours and consumed 2.1 kg (4.6 lb) of food daily. Birds traveled as far as 3,600 km (2,200 mi) from the nest in search of scarce prey, mostly pelagic squid. Ornithologists had long hypothesized that seagoing birds such as petrels use their sense of smell to find food in the open ocean. Research in the past year showed that petrels indeed can sniff out minute amounts of a telltale chemical released by plankton. Gabrielle Nevitt of the University of California, Davis, and Richard Veit and Peter Kareiva of the University of Washington staged a number of experiments in the waters around the sub-Antarctic island of South Georgia. They created small "slicks" of vegetable oil laced with small amounts of the compound dimethyl sulfide (DMS). Microscopic plants in plankton release DMS when consumed by small animals such as krill. Because petrels and their relatives eat such animals, the researchers reasoned that the birds might be able to detect DMS. In fact, DMS turned out to be highly attractive to several seabird species, including Wilson's storm petrels, black-bellied storm petrels, and prions. As storm petrels and their allies often hunt by night, they would gain from their sensitivity to DMS. Furthermore, some areas of the open ocean, where plankton thrive, tend to have higher concentrations of DMS than others. Birds may be able to detect these chemical patterns and use them to help navigate over the otherwise featureless oceans. Two fossil discoveries prompted paleontologists to rethink theories about the diversity of bird life in the age of the dinosaurs. The beautifully preserved bones of Vorona berivotrensis, a new, very primitive bird species unearthed in Madagascar, was the first specimen from the Mesozoic Era (245 million to 66 million years ago) to be found in a large portion of the ancient continent of Gondwana (mainly present-day South America, Africa, India, Australia, and Antarctica). It was also the first pre-Holocene bird (older than 10,000 years) found in Madagascar. The lower limb of the crow-sized fossil indicated a close relationship to the extinct Enantiornithes, the most common group of birds contemporary with the dinosaurs. The second fossil, Eoalulavis hoyasi, from Spain, showed that birds had evolved their efficient, modern style of flight as early as 115 million years ago. According to Luis Chiappe of the American Museum of Natural History, New York City, who helped describe the Madagascan and Spanish fossils, "The diversity of early birds was much larger than we thought five years ago." E. hoyasi was about the size of a goldfinch. Its remains included a well-preserved wing with many feathers in their original positions and showed a crucial stage in the evolution of flight. It lived only about 30 million years after the first bird, Archaeopteryx, but already possessed the alula, or bastard wing, that allows modern birds to maneuver among trees. (JEFFERY BOSWALL) This article updates bird. Literature In many ways 1996 was a dispiriting year for literature. While more books were published than ever before, the rift between serious literary writing and the vast majority of titles grew wider. This was the result, particularly in the "first world," of four converging trends: the continuing absorption of independent publishing houses; the focus on cultural studies that dominated literary theory; the growth of the Internet; and the rise of the superstore. As the number of publishing venues continued to shrink, greater emphasis was being placed on books that would be profitable for their publishers. Editors, consequently, were becoming considerably less willing to risk enthusiasm on a work they were not sure would find a large audience. The virtual coup that contemporary literary theory staged in colleges and universities had by 1996 made its way into publishing as well, as numbers of recent English majors had entered the business as editors or marketers. This had a chilling effect on the purchase of literary fiction in general and resulted in a boom for books that answered the criteria of social usefulness or cultural diversity. Interest in the Internet and its on-line magazines such as Slate and Salon continued to increase as greater numbers of people seemed to be doing their reading in front of computer terminals; simultaneously, the explosion of the World Wide Web, with its "home pages" and "conversation sites," made everyone a virtual author. Finally, the rise of the superstore--where one could buy not only books but audiotapes, compact discs, videotapes, magazines, newspapers, and cappuccino--caused trouble for many independent bookstores and resulted in a 6% decline in their number in 1996. Highlights of the year included a Turkish translation of James Joyce's Ulysses and well-regarded new English translations of the Odyssey and Genesis, as well as new work from such internationally known authors as J.M. Coetzee, Jacques Derrida, Colleen McCullough, Breyten Breytenbach, Tomas Transtrmer, Christa Wolf, Gabriel Garca Mrquez, Carlos Fuentes, Margaret Atwood, Peter Hoeg, Jostein Gaarder, Joyce Carol Oates, Naguib Mahfouz, Wole Soyinka, and David Malouf. (See BIOGRAPHIES.) A poet relatively little known in the West, Wislawa Szymborska, won the Nobel Prize; it was the first time the prize had been awarded to a Slavic woman. (See NOBEL PRIZES.) Internationally, perhaps three trends might be highlighted. As the century drew to a close, more and more writers from around the world were meditating on the century's earlier events, particularly World War II. As well, novels were again addressing political issues as the century's obsession with issues of form--postmodernism, minimalism--began to wane. In many countries--especially France, Turkey, Poland, and Japan--women writers dominated the publishing scene. Though fundamentalist and authoritarian regimes continued to persecute writers, three Iranian women, two of them living in exile in Sweden, enjoyed literary success. (STEPHEN BAUER)