14 DAY TRIAL // For adapting to the environment, organisms have two choices: to change their physiology or to change their behavior, through genetic changes or learning; it is a trade between mutation and innovation. Innovation can be cultural if it propagates to other individuals or groups, maintains along the generations, beyond that of its discoverer and presents a certain degree of stability in its execution by various "users".
We tend to see the apes as having culture, because they are so close to us, but so far, only the chimpanzee display regular cultural innovations in the most various situations. Gorillas very rarely use tools (last year a female was seen throwing sticks towards enemies) and orangutans are very discrete in what concerns the technique. Orangutans too break sticks for getting insects or seeds covered by prickly villosities. Chimps are not only more expressive and very similar to us in their manifestations (greetings, hugs, kisses, sighs, friendly touches on the back, and others).
Technical innovations allow the achievement of large amounts of food, which is more varied or more qualitative. This involves tools, like grass straws, twigs and sticks, which chimps introduce into cavities for getting ants, termites, bee honey and seeds, but also for examining gaps, wounds or objects they fear. Chimps use sticks and leaves for whipping dust, ants, or for brushing. Large leaves are employed for individual hygiene (like cleansing themselves of blood, urine and so on). For cracking nuts, chimps use stones or woods.
But not all use the same mechanisms to get to the same result. In the west, chimps prefer the "hammer-anvil" system (in Ivory Coast, Sierra Leone, Liberia and Guinea), while in the east, termite fishing is the main cultural activity. In Gombe National Park (Tanzania, on the shores of the Lake Tanganyka) chimps eat palm nuts by crashing them against a tough surface, without using the hammer-anvil system, even if they have the necessary raw matter. This means that it is not a question of environment. Chimps in the Tai Forest (Ivory Coast) never use leaves as serviettes, even if this is common amongst the eastern chimps. During the dry season, Fombe chimps introduce leaves into tree cracks to absorb the water stored inside.
Fishing Macrotermes termites ( a savanna genus) is common amongst chimps of Gombe, but in Tai, those termites do not exist, and local chimps eat another 5 types of insects without using the tool system.
Both Tai and Gombe chimps use sticks for catching ants, but differently. Tai chimps use long sticks they introduce into the nests of magnans ants. When the ants have ascended 10-15 cm (4-6 in) on the stick, they spin rapidly the stick, grab it with their mouth and put it out. Gombe chimps wait till the ants have ascended 30 cm (12 in), then they pass the stick through their closed palm. The mass of ants remaining onto their palms is rapidly put into their mouths. The technique is 4 times more efficient than that of the Tai chimps. The fact that Tai chimps do not use sticks for fishing termites may be a sign chimps cannot generalize.
In 2007, researchers have found, for the first time, proofs that chimps dig by using tools in order to eat tubers, roots, and bulbs, in the Ugalla Forest Reserve of western Tanzania, a dry woodland savanna harboring a small chimpanzee population in a habitat very different from the wet forests. Sticks were worn and bore a hard soil crust on one top, a sign they had been used for digging.
Unlike what was previously believed, the diggings were executed during the rainy season which was rich in food, thus tubers were not a last solution for food. Chimps are known to chew tubers and spit out tough fibers. Some of the plants dug by chimps are also used by locals as food or medicine.
Processing a tool, like breaking a twig, its cleaning and flattening at one tip, may suggest that the animal has a minimal representation of the shaped object.
Social innovations are rare, and they refer to the display parades of the males, which throw or beat branches or launch stones towards targets, like other monkeys do as well. They are linked to strategies of "power taking" or opportunism inside the group. Any chimp uses "alliances", "plots" and "flatters" for achieving power, like deparasitizing the coat of a "boss".
Hunting (even if chimps do not use tools for this) can be a social innovation. Plant food makes 75 % of the diet of the chimps, while vertebrate preys represent less than 1 %, but hunting is an important social fact for chimps.
Favorite preys are monkeys, but, if in Gombe this is mostly a solitary activity, in Tai this is mostly a collective action. In both places, prey is shared, that's why, in Gombe, it is more advantageous to be spectator than hunter, while, in Tai, being a hunter comes with many social advantages. Thus, in Gombe, individualism is encouraged, while, in Tai, the cooperation is. This is explained by the ecology in various areas: in Gombe, trees are no taller than 15 m (50 ft), favoring the individual hunting of the monkeys. In Tai, the prey can take refuge up to 50 m (166 ft), and individual action have less success. Also, the way the victims are killed and consumed differs. In Gombe, preys are suffocated, in Tai they are hit against trunks or stones (just like nuts). To reach the bone marrow or the brain, the Tai chimps use sticks they introduce into the bones and the skull.
A 2006 research shocked when it found chimps using tools for hunting. Chimpanzees hunt bare-handed, from baboon offspring to warthog piglets and colobus monkeys, but, in the Senegalese savanna, scientists recorded, on 22 occasions, wild chimpanzees designing "spears" from sticks, to kill small primates named lesser bush babies (a kind of lemurs).
The chimpanzees broke off a branch at one or two ends and, frequently, sharpened one end with their teeth. The tool was jabbed into tree hollows where bush babies sleep. The "spears", on average, were about 24 inches (60 centimeters) long and 0.4 inch (11 millimeters) in circumference. In one case, a chimp was seen successfully extracting, with the spear, a bush baby, which was subsequently torn apart and eaten, but the researchers could not say if the small primate was already dead or not. What made the discovery even more remarkable was who the hunters were: predominantly mature females and immatures/youngsters between two and ten years old.
Another social innovation was observed on wild chimps in the West African village of Bossou in the Republic of Guinea: males steal desirable fruits from local farms and orchards to get the best sex partners. Possessing a sought-after food item, such as papaya, appears to draw even more positive attention from the females. The chimpanzees at Bossou use crop-raiding as an opportunity to obtain and share desirable foods. Fruit-stealing males shared most of the loot with females of reproductive age; especially with a female (within the group) which is extremely attractive for the male chimps, taking part in the majority of consortships (where a chimpanzee couple retreats to the periphery of their community for the male to be able to receive exclusive access to mating). A consortship increases a male's chances of fathering the offspring, as otherwise, both males and females are highly promiscuous, in many cases a female mating with several males at a time. Cultivated plant foods were shared much more frequently than wild plant foods at Bossou, even if getting them meant risky raiding crops, that induced anxiety in the males (rough scratching and other symptoms of anxiety), due to their exposed locations and the human presence.
In chimps, the most important knowledge (and innovation) transmission is made from mother to offspring. The young is suckled until the age of 3 years and keeps staying with his mother even when she has another young. In chimp communities, females are those who migrate to other communities, so that the behavior specific to one community can be later found in another, in cases when female infiltrations have occurred. Dominant females tend to care more of the male offspring, increasing their chances of survival. Males can fight fiercely for mating rights, and this way the mother ensures her lineage. A young male chimp benefiting of prolonged maternal care and a dominant mother had high chances of having a high rank social status.
Even if this is far from human culture, it represents the first cultural manifestations we shared with chimps since we had a common ancestor 5-4 million years ago. In fact, 2 million years ago, human culture was by no means superior to that of the chimps.