Reading — 2026 Jan–Apr Recall Set 83

A For the past decade Dr Engel, a lecturer in environmental sciences at Britain’s Open University, has been collating examples of self-medicating behaviour in wild animals. She recently published a book on the subject. In a talk at the Edinburgh Science Festival earlier this month, she explained that the idea that animals can treat themselves has been regarded with some scepticism by her colleagues in the past. But a growing number of animal behaviourists now think that wild animals can and do deal with their own medical needs. B One example of self-medication was discovered in 1987. Michael Huffman and Mohamedi Seifu, working in the Mahale Mountains National Park in Tanzania, noticed that local chimpanzees suffering from intestinal worms would dose themselves with the pith of a plant called Veronia. This plant produces poisonous chemicals called terpenes. Its pith contains a strong enough concentration to kill gut parasites, but not so strong as to kill chimps (nor people, for that matter; locals use the pith for the same purpose). Given that the plant is known locally as “goat-killer”, however, it seems that not all animals are as smart as chimps and humans. Some consume it indiscriminately and succumb. C Since the Veronia-eating chimps were discovered, more evidence has emerged suggesting that animals often eat things for medical rather than nutritional reasons. Many species, for example, consume dirt a behaviour known as geophagy. Historically, the preferred explanation was that soil supplies minerals such as salt. But geophagy occurs in areas where the earth is not a useful source of minerals, and also in places where minerals can be more easily obtained from certain plants that are known to be rich in them. Clearly, the animals must be getting something else out of eating earth. D The current belief is that soil—and particularly the clay in it—helps to detoxify the defensive poisons that some plants produce in an attempt to prevent themselves from being eaten. Evidence for the detoxifying nature of clay came in 1999, from an experiment carried out on macaws by James Gilardi and his colleagues at the University of California, Davis. Macaws eat seeds containing alkaloids, a group of chemicals that has some notoriously toxic members, such as strychnine. In the wild, the birds are frequently seen perched on eroding riverbanks eating clay. Dr Gilardi fed one group of macaws a mixture of harmless alkaloid and clay, and a second group just the alkaloid. Several hours later, the macaws that had eaten the clay had 60% less alkaloid in their bloodstreams than those that had not, suggesting that the hypothesis is correct. E Other observations also support the idea that clay is detoxifying. Towards the tropics, the amount of toxic compounds in plants increases—and so does the amount of earth eaten by herbivores. Elephants lick clay from mud holes all year round, except in September when they are bingeing on fruit which, because it has evolved to be eaten, is not toxic. And the addition of clay to the diets of domestic cattle increases the amount of nutrients that they can absorb from their food by 10-20%. F A third instance of animal self-medication is the use of mechanical scours to get rid of gut parasites, in 1972 Richard Wrangham, a researcher at the Gombe Stream Reserve in Tanzania, noticed that chimpanzees were eating the leaves of a tree called Aspilia. The chimps chose the leaves carefully by testing them in their mouths. Having chosen a leaf, a chimp would fold it into a fan and swallow it. Some of the chimps were noticed wrinkling their noses as they swallowed these leaves, suggesting the experience was unpleasant. Later, undigested leaves were found on the forest floor. G Dr Wrangham rightly guessed that the leaves had a medicinal purpose—this was, indeed, one of the earliest interpretations of a behaviour pattern as self-medication. However, he guessed wrong about what the mechanism was. His (and everybody else’s) assumption was that Aspilia contained a drug, and this sparked more than two decades of phytochemical research to try to find out what chemical the chimps were after. But by the 1990s, chimps across Africa had been seen swallowing the leaves of 19 different species that seemed to have few suitable chemicals in common. The drug hypothesis was looking more and more dubious. H It was Dr Huffman who got to the bottom of the problem. He did so by watching what came out of the chimps, rather than concentrating on what went in. He found that the egested leaves were full of intestinal worms. The factor common to all 19 species of leaves swallowed by the chimps was that they were covered with microscopic hooks. These caught the worms and dragged them from their lodgings. I Following that observation, Dr Engel is now particularly excited about how knowledge of the way that animals look after themselves could be used to improve the health of livestock. People might also be able to learn a thing or two, and may, indeed, already have done so. Geophagy, for example, is a common behaviour in many parts of the world. The medical stalls in African markets frequently sell tablets made of different sorts of clays, appropriate to different medical conditions. J Africans brought to the Americas as slaves continued this tradition, which gave their owners one more excuse to affect to despise them. Yet, as Dr Engel points out, Rwandan mountain gorillas eat a type of clay rather similar to kaolinite—the main ingredient of many patent medicines sold over the counter in the West for digestive complaints. Dirt can sometimes be good for you, and to be “as sick as a parrot” may, after all, be a state to be desired.

A. Researchers have studied the similarities between chimpanzees and humans for years, but in the past decade they have determined that these resemblances run much deeper than anyone first thought. For instance, the nut cracking observed in the Tai Forest is far from a simple chimpanzee behaviour; rather it is a singular adaptation found only in that particular part of Africa and a trait that biologists consider to be an expression of chimpanzee culture. Scientists frequently use the term “culture” to describe elementary animal behaviours, but as it turns out, the rich and varied cultural traditions found among chimpanzees are second in complexity only to human traditions. B. During the past two years, an unprecedented scientific collaboration, involving every major research group studying chimpanzees, has documented a multitude of distinct cultural patterns extending across Africa, in actions ranging from the animals’ use of tools to their forms of communications and social customs. This emerging picture of chimpanzees not only affects how we think of these amazing creatures but also alters human beings’ conception of our own uniqueness and hints at ancient foundations for extraordinary capacity for culture. C. Homo sapiens and Pan troglodytes have coexisted for hundreds of millennia and share more than 98 percent of their genetic material, yet only 40 years ago we still knew next to nothing about chimpanzee behaviour in the wild. That began to change in the 1960s, when Toshisada Nishida of Kyoto University in Japan and Jane Goodall began their studies of wild chimpanzees at two field sites in Tanzania. Goodall’s research station at Gombe—the first of its kind—is more famous. D. In these initial studies, as the chimpanzees became accustomed to close observation, the remarkable discoveries began. Researchers witnessed a range of unexpected behaviours, including fashioning and using tools, hunting, meat eating, food sharing and lethal fights between members of neighbouring communities. In the years that followed, other primatologists set up camp elsewhere, and, despite all the financial, political and logistical problems that can beset African fieldwork, several of these out-posts became truly long-term projects. As a result, we live in an unprecedented time, when an intimate and comprehensive scientific record of chimpanzees’ lives at last exists not just for one but for several communities spread across Africa. E. As early as 1973, Goodall recorded 13 forms of tool use as well as eight social activities that appeared to differ between the Gombe chimpanzees and chimpanzee populations elsewhere. She ventured that some variations had what she termed a cultural origin. But what exactly did Goodall mean by “culture”? The diversity of human cultures extends from technological variations to marriage rituals, from culinary habits to myths and legends. Animals do not have myths and legends, of course. But they do have the capacity to pass on behavioural traits from generation to generation, not through their genes but by learning. For biologists, this is the fundamental criterion for a cultural trait: it must be something that can be learned by observing the established skills of others and thus passed on to future generations. F. What of the implications for chimpanzees themselves? We must highlight the tragic loss of chimpanzees, whose populations are being decimated just when we are at last coming to appreciate these astonishing animals more completely. The bushmeat trade is particularly alarming: logging has driven roadways into the forests that are now used to ship wild-animal meat—including chimpanzee meat—to consumers as far afield as Europe. Such destruction threatens not only the animals themselves but also a host of fascinatingly different ape cultures. G. Perhaps the cultural richness of the ape may yet help in its salvation, however. Some conservation efforts have already altered the attitudes of some local people. A few organizations have begun to show videotapes illustrating the cognitive prowess of chimpanzees. One Zairian viewer was heard to exclaim, “Ah, this ape is so like me, I can no longer eat him.” H. How an international team of chimpanzee experts conduct the most comprehensive survey of the animals ever attempted? Scientists have been investigating chimpanzee culture for several decades, but too often their studies have contained a crucial flaw. Most attempts to document cultural diversity among chimpanzees have relied solely on officially published accounts of the behaviours recorded at each research site. But this approach probably overlooks a good deal of cultural variation for three reasons. I. Firstly, scientists typically don’t publish an extensive list of all the activities they do not see at a particular location. Yet this is exactly what we need to know—which behaviours were and were not observed at each site. Second, many reports describe chimpanzee behaviours without saying how common they are; without this information, we can’t determine whether a particular action was a once-in-a-lifetime aberration or a routine event that should be considered part of the animals’ culture. Finally, researchers’ descriptions of potentially significant chimpanzee behaviour frequently lack sufficient detail, making it difficult for scientists working at other spots to record the presence or absence of the activities. J. To remedy these problems, the two of us decided to take a new approach. We asked field researchers at each site for a list of all the behaviours they suspected were local traditions. With this information in hand, we pulled together a comprehensive list of 65 candidates for cultural behaviours. K. Then we distributed our list to the team leaders at each site. In consultation with their colleagues, they classified each behaviour in terms of its occurrence or absence in the chimpanzee community studied. The key categories were customary behaviour, habitual, present, absent, and unknown. We should note, however, that certain cultural traits are no doubt passed on by a combination of imitation and simpler kinds of social learning. Either way, learning from elders is crucial to growing up as a competent wild chimpanzee.

The way we think about architecture in schools has come a long way. Once, studying architecture in the art class meant learning to appreciate great buildings art-history style, through slide presentations. In recent years, though, the American Institute of Architects has fostered the idea that the process of architectural design, not just the appreciation of architecture, is a beneficial aspect of the art curriculum (Sandler, 1989). The value of architectural design is that it is the concrete training ground for a broadly applicable creative process. Architectural training can help people design structures to meet needs. It can help teachers design lessons to meet needs, help representatives design laws to meet needs, or help farmers design crop rotations to meet needs. Furthermore, it provides hands-on experiences that reinforce learning in various other subjects, from math to social studies. In the ongoing dialogue about architecture in one middle school art curriculum, many believe students should actually build the structures they design in their courses. Although the technology and expertise required of modern architecture can prohibit students from actually realizing their designs, traditional architectural materials and methods remain quite accessible to the art classroom. Traditional architectural materials, such as earth, clay and straw, are cheap, easy to work with and readily available. Further, when students participate in the construction or preservation of a traditional earthen structure in their local community, they engage in a form of experiential learning and they are motivated to invest in the project. This is evident in a case study of an adobe conservation project with middle school students in the town of Zuni, New Mexico, in the Southwestern United States. Traditional architecture reaches back to preindustrial America, when local resources and cultures produced structures in styles unique to each region. In New Mexico, examples of hand-built earthen structures still abound. The region has seen some decline in traditional architecture as industrialization has brought new building codes and materials; however, the traditional, non-industrial home, either preserved from earlier generations or newly built, remains in use. Traditional building materials and the land that supplies them are so accessible that handcrafting a house still remains feasible. Thus, with no technical expertise and little cost, middle school students can participate in the construction or preservation of a traditional earthen structure. During the project, a student will get to know the materials, understand the chemistry, solve problems, work with classmates, and exercise muscles. The student can apply knowledge of design principles and the creative process while participating in a cooperative effort. But most significantly, this type of project-based activity motivates students to invest intellectually. The benefits extend beyond academic knowledge. Students develop a tangible connection to their local heritage and environment. They learn the value of sustainable, low-impact building practices and gain respect for craftsmanship. Such projects can foster community pride and intergenerational learning when local elders or artisans share their knowledge. While modern construction techniques dominate the professional world, the educational power of traditional, hands-on building offers a unique way to teach problem-solving, teamwork, and cultural appreciation in a manner that is both engaging and deeply meaningful.