3 Tool use and culture in ape and human societies
Another surprising discovery first reported by Jane Goodall in 1960, was the routine use of tools by the Gombe chimpanzees for obtaining food. Since then, observations on other groups of chimpanzees have highlighted the diversity of tool-using techniques. The TV programme and LoM Chapter 10 provide fascinating examples of the techniques used; some are remarkably complex and ingenious.
Question: On the basis of the description in LoM Chapter 10, what tool-using techniques are employed by chimpanzees to obtain food?
Chimpanzees 'fish' for termites by inserting a twig that they have stripped into a hole in a termite hill. The chimpanzee pulls the twig out of the hole and, using the lips and tongue, sucks up the insects that adhere to it [photograph on p. 292]. Water is collected from a small tree hole by inserting a crumpled leaf into the hole. The most sophisticated example of tool use involves breaking open hard nuts by a hammerstone and anvil. The chimpanzee places the nuts on the anvil and hits them with the hammerstone until the shell cracks open [p. 291].
As you saw in the TV programme, use of an anvil and hammerstone involves each hand being used for a different purpose and is one of the most complex examples of tool use observed in animals. A research group from Kyoto University, Japan, is studying tool use by chimpanzees living in Bossou, Guinea. These chimpanzees select two types of stone: large, flat anvil stones and rounded hammerstones. Handfuls of palm nuts are brought for processing to a selected anvil or platform stone. Shallow cavities worn on the anvil stones, and adjacent piles of old nutshells, indicate that they have been in use for a long time. Those who observe this behaviour in the field report a degree of expertise in these animals that far exceeds the proficiency of humans when they first try the technique. What is fascinating is that villagers around Bossou use the same technique: their tools resemble those of the chimpanzees. We will never know whether the chimpanzees learned the technique from the humans or vice versa!
The Bossou researchers investigated how young chimpanzees learn the technique; fine coordination is needed and it takes the young chimpanzees about three to four years to learn the skills. Infant chimpanzees join the group at the nut-cracking area and watch the adults, and play with the nuts and stones. They often play a game that involves putting a nut on a stone and hitting it with a hand or foot. Mothers give their infants kernels of cracked nuts to eat, so the infants learn to associate their play activity with food. Mothers at Tai Forest, Côte d'Ivoire, leave nuts, hammerstones and anvils arranged correctly for use by infants, and sometimes perform nut-cracking in slow motion in front of their offspring - rather like a chimpanzee school. The Dutch primatologist Frans de Waals interprets the infants' behaviour as socially motivated. The young chimpanzees imitate their mothers and have a strong urge to act like her. By doing so, they learn the 'language' and culture of the group. After three or four years of such messing about with nuts and stones, the young begin trying to use the stones as anvils and hammers. The motivation to do so must be very strong; the years of learning often result in little more than crushed fingers, without the reward of obtaining a kernel.
All these observations suggest that we can add tool use to our list of similarities between humans and chimpanzees. Such a skill was formerly regarded as one of the unique attributes of humans - you may be familiar with the phrase: 'Man the tool-maker'.
When Jane Goodall first reported her observations to Louis Leakey (famous for having discovered many of the fossil hominid specimens in Africa), he said: 'Now we must redefine tool, redefine Man or accept chimpanzees as humans'. Of course, there is a distinction to be made between the use of tools (as in chimps) and examples of tool manufacture, on the scale seen in the earliest human settlements. For humans, the design, manufacture and use of complex tools is very much part of our 'culture'. If culture is defined in human terms as complex technology, agriculture, art, science and literature, then clearly animals, including apes, do not appear to have it. But culture need not be defined so narrowly, as I'll argue later. In each human population, or social group, aspects of the population's culture are taught to offspring - the long childhood of Homo sapiens provides plenty of time for cultural learning.
In the TV programme, DA provides us with a glimpse of the spectacular diversity of human cultures.
Watch the TV programme from 29.38-43.40 and jot down notes on how the San bushmen of the Kalahari, the Fulani people of Mali and the Dogon of Mali and Burkhina Faso obtain their food. Drawing on these notes, explain in less than 200 words how the three groups obtain their food, highlighting comparisons where appropriate.
San people rely on wild animals for meat, and hunt in small groups, using the persistence technique. Initially, the men look for tracks of prey animals, e.g. kudu, and follow them. When a herd is spotted, the hunters select their animal and separate it from the herd. Tracking and pursuit may take hours (or days) and requires considerable endurance during the heat of the day. When the kudu shows signs of tiring, a single hunter chases it to the point of exhaustion, finally spearing the collapsed animal. San women collect tubers and plants to supplement the meat.
In contrast, the Fulani are nomadic cattle herders who follow their cattle herds as they migrate seasonally to their traditional grazing areas. In this way, the Fulani always have a large supply of animals available for milk, meat and hides.
The Dogon people are agriculturalists and live sedentary and settled lives in villages, in contrast to the nomadic San and Fulani peoples. The principal crop grown by the Dogon is millet, which is stored in the numerous granaries of the villages. The villagers mark good harvests by celebratory dancing, dressed in large colourful masks.
These three groups - the San, the Fulani and the Dogon, all living on the continent of Africa - have different techniques for obtaining their food, and different ways of life. How a people obtain and prepare their food is a central part of their culture and links with all aspects of life, including tool use, social interactions, and even art. Our own culture relies on agriculture, including plant and animal domestication, for food; like the Dogon, the vast majority of the human population living today have a more sedentary lifestyle, but agriculture is no less significant.
This brief survey, based on a little more than 10 minutes of a TV programme, can do scant justice to the huge range of culture in human populations. But even the briefest of surveys should serve to loosen any preconceptions as to what constitutes culture. You will recall from LoM Chapter 10 DA's mention of orangutans in the forests of northern Sumatra having a unique culture linked to their techniques for feeding on Neesia fruit. You may have been puzzled by his use of the word 'culture' in relation to the feeding behaviour of a great ape. In the early 1950s, the Japanese anthropologist Kinji Imanishi proposed that culture should be defined as a form of behavioural transmission that does not depend on genetics. As apes live in social groups, and take up to 13 years to reach maturity, there is plenty of time for cultural information to be transmitted to younger generations. Imanishi's view of culture is accepted by many biologists now, displacing the earlier view, neatly summarised by the declaration (dated 1959) that 'man and culture originated simultaneously; this by definition'. I've mentioned how infant chimpanzees at Bossou learn from adult members of their group the skills needed for breaking open palm nuts - behavioural transmission is indeed not dependent on genetics. Use of anvils and hammerstones is unusual and has only been observed in a few groups of chimpanzees, including those at Bossou. And ape culture, as with humans, varies from one location to the other. In some areas in which chimps are living, nuts, stones and anvils are available and yet these animals show no signs of developing the palm-nut cracking habit of conspecifics living in Bossou.
Furthermore, behaviours not linked to obtaining food are also observed in particular chimpanzee groups and not in others. You should recall that in the TV programme at 14.12, you saw the Ngogo chimpanzees indulging in handclasp grooming. The behaviour involves one chimpanzee taking the hand of another and then raising the linked hands high into the air, forming a symmetrical A-frame, with the free hand of each grooming the armpit of the other. This posture is typical of a group living at Mahale in Tanzania, but is not seen in a group living on the same side of Lake Tanganyika, 170 km away, in Gombe National Park. Researchers who observed this behaviour conclude that it is cultural, and transmitted through the group along social lines. The handclasp is therefore one of the cultural characteristics that define the Mahale and Ngogo troupes of chimpanzees - manifestations of culture perhaps not fundamentally different in kind from those witnessed in Activity 4.
Now that we have questioned tool use and culture as uniquely human attributes, you may be wondering what is distinctive about humans. In the rest of this study period, I'll be concerned with human attributes that appear to be unique, discussing them in the context of what we know about the evolution of our own species, Homo sapiens.