Why Do Great Apes Merit Being Awarded World Heritage Status?
The Problem
There are five forms, or seven species, of great apes on earth. Humans are one of the great apes -just as we are one of the primates, and one of the mammals. The four forms of non-human great apes which belong to the family Hominidae (Groves 1989) are a bridge between humans and the other animals. They are the orangutans of Borneo (Pongo pygmaeus, 2 subspecies) and Sumatra (Pongo abeli), eastern gorillas (Gorilla beringei, 2-3 subspecies), western gorillas (Gorilla gorilla, 2 subspecies), chimpanzees (Pan troglodytes, 4 subspecies), and bonobos (Pan paniscus). They link us to our biology and to our world. They have many human-like characteristics. Great apes clearly stand apart from the other primates in a number of respects, the most important being their special development of mental sophistication, such as an elementary capacity for symbolic thought and self-recognition, and the related characteristics such as exceptional intelligence and cultural development.
Whereas the human species numbers in the billions and is expanding at an alarming rate, the opposite is true for the other species. These are counted in tens of thousands or at the most a hundred thousand individuals (Ape Alliance 1998, Table 1). Their numbers have decreased dramatically in the past few decades, and there is no indication that the rate of decline is decreasing. On the contrary! Continuing habitat destruction by logging and forest conversion to farmland, the partitioning of remaining habitats into fragments that are too small to support sustainable populations, and, last but not least, poaching bring many of the remaining populations to the
brink of extinction. Poaching has become an increasingly severe threat, as it practiced not only by locals but also by roaming military factions. In addition, traders are ruthlessly trying to capture young individuals for the pet trade and -especially in Africa- to obtain bushmeat. In some of the major habitat countries, all this is aggravated by political instability and social unrest.
Analyses of recent developments indicate that the great apes will become extinct in the wild in this century unless action is undertaken immediately to counteract the threats they face (Marshall et al. 2000). Therefore, humankind must do whatever it can to prevent this tragedy before it is too late and some of the most interesting creatures on this planet, our nearest relatives, vanish forever from this earth as naturally living populations.
The special qualities of the non-human great apes that merit awarding them World Heritage Status are: (1) their phylogenetic closeness to humankind, and (2) their mental, i.e. emotional and cognitive, capacities, which are related to their exceptional intelligence and cultural development. (3) Social sophistication
has also been clearly documented for at least most of them. In addition, (4) they have a special relevance for science. Their physical and mental resemblance to ourselves makes them invaluable for the science of humankind.
Phylogenetic Closeness to Humans
Traditional biology, such as comparative anatomy, has long since recognized the close phylogenetic relationship between non-human great apes and humans (Huxley 1863). They share many morphological characteristics with us, e.g. in the shape and number of muscles and bones and overall proportions of body
parts. Human and non-human great apes have flat chests, long arms and flexible shoulders, and lack an external tail (Pilbeam 1972). They cannot swim, except for humans. All of them usually lie in beds when sleeping. They have similar facial expressions; for example, they can laugh (van Hooff 1967). Humans and the genus Pan (chimpanzees and bonobos) share 98.4% of their genetic substance, the DNA. Two species of gorillas share 97.7% with us and two species of orangutans 96.4% (Sibley & Ahlquist 1984).
Mental and Social Characteristics
Non-human great apes express not only the primal emotions of anger and fear but also many that are often categorized as "human emotions," including sadness, joy, despair, jealousy, and sympathy (Goodall 1986). They have more human-like mental capacities than any other species. The sixties brought the first successful studies in which chimpanzees were taught a language system (Gardner & Gardner 1969, Premack 1971, Rumbaugh 1977, Fouts & Mills 1997). Gradually, it has become more evident that these creatures have elementary symbolic thought. There is a bonobo who can understand spoken English sentences (Savage-Rumbaugh & Lewin 1994). This bonobo, who has been exposed to English since birth, knows some 1,000 words and seems to understand grammar as well. When great apes look into a mirror, they can recognize themselves and show fascination in their own facial expressions (Gallup 1970, 1982). They are the only animals for which there is convincing evidence of true imitation(Custance et al. 1995), a capacity highly conducive to the development of culture (see below).
Recent research has suggested that non-human great apes can have a "theory of mind" (Premack & Woodruff 1978) i.e. they can take the perceptual perspective of others, and may form a mental representation of the knowledge of others and attribute intentions to them. These capacities may also enable them to feel forms of empathy, as evidenced by observations of behavior, such as social consolation and other forms of altruism (Goodall 1986, de Waal 1982, 1996). Great apes adopt infant orphans who have lost their mothers, and in many instances orphans survive their mothers' deaths due to their foster parents' care (Goodall 1986, Nishida 1994). These characteristics, which they share with us, undoubtedly enable them to develop the complex societies that we see especially in the genus Pan. These traits also enable them to negotiate with, to manipulate, and even deceive others. They display a Machiavellian type of intelligence in regulating their social relationships (de Waal 1982, Nishida 1983, Byrne & Whiten 1988). In such activity, both loyalty and opportunism play a role. Thus, adult male chimpanzees show tactical negotiation and selective tolerance and permissiveness (e.g. in access to sexual mates) toward coalition partners. Mutual support and the exchange of services and favors take the form of implicit social contracts based on expectations about one another's behavior and a sense of obligation (de Waal 1991). These expectations can thus acquire a normative character. Here, we encounter the roots of morality (de Waal 1996).
Behavioral Flexibility and Tool Use
All of the non-human great apes show immense curiosity about every nook and cranny in their environment. The ability of chimpanzees, bonobos and orangutans to make and use tools has been extensively documented in the wild (Kano 1992, McGrew 1992, van Schaik et al. 1996). They do so in flexible manners both in the wild and in captivity (Beck 1980).
When chimpanzees become ill, they selectively eat certain herbs or the bitter pith of certain plants. Chemical analysis has shown that these plants contain elements that can kill bacteria in low concentrations (Huffman 1998). Chimpanzees, bonobos and gorillas also swallow hairy leaves to mechanically evacuate intestinal helminthes (Huffman 1999). Thus, the great apes engage in self-medication, making use of knowledge of the medicinal properties of plants, which undoubtedly is passed on in the form of cultural habits.
Culture
The above examples already emphasize the role of culture in great ape societies. Every known chimpanzee population has its own unique culture of behavioral traditions. Chimpanzees have been studied in various parts of Africa, and many behaviors have been discovered to be specific to certain regions (Whiten et al. 1999). For example, the technique of stone-hammering is confined only to some parts of west Africa, the use of sticks in digging for termites is known only for the chimpanzees of central Africa, and fishing for arboreal carpenter ants is limited to two sites in Tanzania. In addition to such variations in food repertoire and food extraction techniques, chimpanzees show large local variations in social behavior patterns. These include courtship gestures, grooming postures, intimidation displays, and pant-hoot calls (Mitani et al. 1992, Nakamura et al. 2000, Nishida 1994, Whiten et al. 1999). Furthermore, there are variations in the removal of external parasites (Boesch 1996, Zamma in press) and water contact behavior (Nishida 1980). Such behavioral differences between local populations have also been shown to exist in other great apes, especially recently in populations of orangutans (van Schaik et al. 1996).
Conclusions
The almost paradigmatic change in our thinking about nonhuman great apes that has taken place in recent decades is only the beginning of scientific explorations that can also contribute to a better understanding of ourselves as a species, of our natural characteristics, and of the ways these are expressed in a variety of cultural manifestations. Such understanding will be possible only if we can study the characteristics of our nearest relatives in their fullest expressions, that is, in the ecological context where their physical and mental, their social and cultural characteristics have evolved and have achieved their evolutionary adaptive significance. Especially important are the broad range of ecological conditions in which each great ape species is found and the variations in relevant ecological factors because these provide us with insights in the flexibility and adaptiveness of the behavior of "our kinds of animals " (Wrangham et al. 1994).
In various countries philosophers and law theorists are advocating the attribution of a special status to nonhuman great apes (e.g., Cavalieri & Singer 1993, Peterson & Goodall 1993). This is based on the growing scientific conviction that these creatures have evolved personalities. This has led to the moral obligation to award them the constitutional status and legal rights of preverbal human children and mentally handicapped humans. New Zealand was the first country where this concept was put into law (Taylor & Leonard 1998).
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