The study of nestbuilding behaviour in the higher apes is based on roughly 50 years of field research and about 200 years of observation. In 1929, chimpanzees, gorillas and orangutans were systematically studied by the American Primatologist couple, the Yerkes. They for the first time scientifically termed nestbuilding as "constructivity" and theoretically placed it at the beginning of an evolutionary process. Their conclusion: "...nesting behaviour illustrates the appearance and phylogenetic development of dependence on self-adjustment to increasing dependence on manipulation or modification of environments as a method of behavioural adaptation." (Yerkes 1929:564; see also Egenter 1983, 1987). In terms of architectural theory, this conclusion introduces a basic situation which can be used to research the development of human building behaviour or architectural evolution in the anthropological sense. Over the last 50 years an important question has been clarified. Nestbuilding is to a great extent learned behaviour. Earlier zoologists considered it merely motoric programmed instinctive behaviour. However, the surveys of Bernstein (1962, 1969) and Lethmate (1977) strongly questioned this opinion. The ability to weave branches into a stable construction requires a definite learning process. Nestbuilding behaviour consequently can be seen as a tradition in the human sense, and an important one, because it shows us that the hand can be understood as the primary tool. Nestbuilding thus becomes a primary type of handycraft in the factual and evolutionary sense of the word.
The higher apes are nomads. In search of food the animals daily wander over a more or less clearly defined home range and rest at "customary used nesting places" (Harrison 1969). Every night is spent in a different place. This is the source of a routine for nestbuilding behaviour. All three species of higher apes from a certain age (3-4), every night build themselves at least one new nest. On average this means about 10-15 thousand nests over the life of an ape, a virtual tower of 11 to 16 times the height of the Eiffel-tower in Paris. A really remarkable life-opus!
The construction process is rather stereotyped. In trees the animal stands or squats on two legs, with its arms it pulls about three thick branches towards its body, bends them, presses them down under his feet and weaves them into a stable round platform of about 60 to 80 cm in diameter (fig. 1 + 2). Then thinner branches and twigs are woven into a wreath. Finally the platform is cushioned with twigs broken off and with plucked leaves. Uneven spots are levelled by knocking with the back of the hand. The whole procedure lasts about one to five minutes depending on the animals abilities. At the end the constructor lies comfortably down in the finished nest and falls asleep. High up in the crown of the tree it safely passes the night until the first light of the next morning.
There are ground-nests which may take the form of grass-, foliage- or twig-nests close to the ground or other constructions in underwood bushes or bamboo-groves reaching heights of 2-4 m (fig. 3 + 4). The former in general are simply made by heaping up materials in a circular form, whereas the latter are stable constructions standing vertically in space. In bamboo groves the heavy animal hangs on the bamboo stalks by his arms, bends them down and weaves them essentially in standing position into a stable framework. After checking his work the animal climbs up and lies down for sleep or rest.
The differentiation between tree- and groundnests is extremely important, because these two environments are entirely different in regard to the animal's movements. In the crowns of the trees the apes move vertically by climbing and horizontally by swinging (arboreal locomotion), in contrast with terrestrial locomotion. The animals use the stable surface to move on on four or two legs - in the latter case like man - and have a quite different access to plants etc. than in the vertically structured environment. In regard to the physical evolution, in particular to the erection of the body the hands freed from use in locomotion, the distinction of arboreal and terrestrial environments in the habitat is of great importance, as is the transition from one to another in evolutionary theory. But it has been little noticed that nestbuilding is represented in both environments and that it shows different technical characteristics. In the case of the tree nest some strong horizontal branches are enough to support the platform. Stability is provided by the physical conditions of the tree. Variation is limited by a limited situation. In contrast to this the materials offered on the ground are of much greater variety and this variety is accessible. The groundnests are therefore more differentiated in terms of construction and form. They vary from heaped types on the ground to woven structures on bushes and to stable and vertically standing structures. This typology can be interpreted in terms of an elementary evolution. The bamboo tower certainly resembles human structures. Its stalks are joined by weaving and tying knot-like slings and it shows tectonic qualities, e.g. standing vertically stable in space. Its foundations are naturally provided by the rooted stalks. It definitely meets two criteria generally thought as of human origin: the stable triangle in a vertical constructive frame. Should these 'discoveries' have to be attributed to the higher apes?
In terms of physical anthropology this type of terrestrial nest raises questions of far-reaching significance for the human evolution. Is this first constructor about to rebuild himself physically with his routined nestbuilding behaviour? Did this constructive routine help to develop the precision grip of the hand as a tool? Did this constant control of weaving and cushioning activities sharpen the eye for close work? Did an increasing capacity of remembering reliable ways of construction influence the development of the brain? Did the routine activity of vertical constructions lift the body of the constructor into the vertical position?
The relation of the nest to the life of its users is very intimate. Its functions are remarkably complex:
Protection: The nest primarily gives the security of a protected and stable place during the nocturnal phase of the apes' daily life. In this phase the animal is not fit for locomotion; in the dark the three dimensional vision of the higher apes is practically inoperative. With their platform the animals not only protect themselves against predators, as is often maintained in literature. Perhaps more importantly they bridge the darker half of their existence during which they are not adapted to their environment. And they also satisfy the physical need of their great bodies for recreation in a horizontal position.
Home: Van Lawick-Goodall has described the nests of chimpanzees as "sickbeds". Animals shot by hunters use their last energies to build their last nest which keeps them from falling. The nest is the last place of refuge.
Mother-child-nest: The nest of mother and child physically reproduces the development of the mother and child relation. Apes spend about two to three years in the nest of their mother. During this time the child gradually learns to build a nest. The long close contact to the mother's bodily warmth contributes to a sense of safety in the nest.
Settlement: The nests of a group form an elementary settlement in which individual characters and social relationships are expressed by the relative distance and location of the nests (fig. 6).
Orientation: The durability of the nest artifacts is remarkably longer than the factual use, which in general is only one night. Nests left behind by the animals last two months on average. Unfortunately their semantic function in the system of the apes' orientation has not yet been studied.
Without doubt these five functions of nestbuilding are deeply woven into the life of the animals in the wild. It also becomes clear that the real significance of the nest in the everyday life of the higher apes becomes obvious only, if the nestbuilding behaviour is studied using constructive, spatial and functional criteria, that is to say with the instruments of architectural theory. From this perspective, nestbuilding behaviour becomes extremely fertile in terms of evolutionary theory. Architectural research could thus greatly enrich today's limited, and merely technical image of 'homo faber'. If the architect-anthropologist could show that some of his essential professional criteria - man in relation to his constructively marked place and traditionally conceived space - are and were always part of a human orientation system merging with all types of human expression (language, thought etc.) he might bring new and very humane concepts to the study of culture (Egenter 1986a, 1988a, 1990).
1)Adult female chimpanzee builds her nest in the crown of large palm-tree (acc. to Goodall 1962)
2)"Weaving" the crosspieces (acc. to Goodall 1962)
3)Construction methods of gorilla groundnests (acc. to Bolwig 1959)
4)Schematic representation of six chimpanzee nests (acc. to Izawa/Itani 1960)
5)Mother-child relation in its developmental stages as reflected in nest-forms (acc. to Kawai/Mizuhara 1959)
6)Diagram showing spatial location of a group of six nests constructed and used by gorillas in mountain forest (acc. to Kawai/Mizuhara 1959).
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