Redefining Culture -- Chimpanzees and Hunting
One way human culture is often defined is the manner in which humans are able to manipulate their environment through external means -- tools. There are many instances of certain animal populations using pieces of the environment; sticks, stones, branches, etc., as tools to assist with food gathering or opening of seeds, mollusks, etc. However, true tool making is taking an object and manipulating it into something different from its original form for a specific purpose. To do this, scientists have always believed that there was active cognition involved -- the ability to visualize a problem, find and refine a solution, and use that solution as the means to an end. There have been numerous animal experiments looking at the reasons certain stimuli allow for tool making. For example, Wolfgang Kohler placed food just outside a caged chimpanzee's reach, resulting in tool making or other innovations designed to manipulate the environment for the betterment of the individual (Kohler, 1992).
It now appears there is a gap in our understanding of just how far tool making can evolve in non-human species. In a 2007 article from Current Biology, researchers found that a group of chimpanzees from Senegal not only construct tools, they plan their use, and carry out missions with the tools -- the tools happen to be spears, and this is the first account of habitual tool use during vertebrate hunting by nonhumans. The two scholars, Jill Pruetz and Paco Bertolani, have spent their careers studying primate behavior. Pruetz is an environmental biologist and primatologist in the Department of Anthropology, Iowa State University who also does a great deal of work with the National Geographic Society ("Emerging Explorers," 2010). Bertolani is using the savanna work to complete his PhD at Cambridge University in biological anthropology. He is particularly interested in the way ranging patters are associated with contrasting sub-environments (savannas vs. tropical forests) and the way human habitation is encroaching upon those enviroments ("Paco Bertolani," 2010).
The observations on this tribe were recorded during two different 30 days periods, March 2005 and July 2005. The hunts were done by the Chimpanzees fashioning tools in attempts to remove bush babies from cavities in the hollow branches of tree trunks. Several organized steps were taken to prepare the tools, organize the hunt, and sequence a hierarchy to capture the prey once it was extracted. Further, when one tool did not work adequately, the chimpanzees alternated (trimmed) that tool or changed it in some way to be more effective. While Chimpanzees do not normally hunt for meat, this behavior was common enough in this particular tribe to lead the researchers to assume that they had acquired a taste for this type of meat. However, unlike other food gathering patterns, and possibly due to the size of the prey, very little food sharing occurred. Tool making techniques and learning, though, were commonly shared by adults to younger chimps, who then attempted to emulate that behavior (Pruetz and Bertolani, 2007).
This, of course, confirms earlier studies by the famous Chimpanzee researcher, Jan Goodall, who showed that not only could Chimpanzees construct and use tools, but that they were far from the consistently peaceful vegetarians of lore (Public Broadcasting Corporation, 1996).
Tool Making in the Animal World - For a number of years anthropologists debated the definition of culture. Some defined culture as the ability to format language, some by learned or imitative behavior, and some by tool making. One debate in the subject focuses on whether the acquisition of tool-making helped transform primitive humans into modern humans by increasing cognitive function, or whether the transformation of environments (we adapt environments to us) triggered more robust and complicated tool making. In a way, it is similar to the chicken and the egg argument, but the idea that using technology to change our environment and habits (e.g. fire, cooking, and stone tools) did put primitive humans at a decided advantage against other species (Garner, 2009). For humans, the dietary and safety advantages that tools caused from Homo Habilis to Homo Erectus and beyond are clearly evolutionary forward steps because of the use of tools; better food, greater chance of making a kill instead of just scavaging, more efficient processessing of that food, more amino acids and fats that allow for greater cognitive development, and so on (Munkittrick, 2009).
However, if culture is learned behavior, immitative behavior, or tool making then many animals have culture and we cannot place humans at the top of the hierarchy. Primate species show common cognitive skills: evidence of tribe and object-permanance, cognitive mapping, categorization of objects, creative problem solving, tool making, and organizational behavior. They share social skills, have kinship and rank, recognize third-party social relationships, predict future behavior and cooperate in complex problem solving scenarios (Tomasello, 1999).
In addition, scientists note that it is not just primates who use tools for getting food, grooming, shelter building, and more. These species include birds, cetaceans, elephants, otters, and even octopi. Tools, of course, may be defined in numerous ways: an object that is modified to fit a purpose or make a change in the environment (Hauser, 2001); the use of objects other than the animal's own body to extend their physical influence in the world (Jones and Kamil, 1973); or, an object carried with the intent for future use and/or manipulation (Finn, Tregenza and Normal, 2009).
Non-human tool use implies that the animal has knowledge of the relationships between objects, the environment, and potential effects. We can make the distinction, though, between behaviors and species that use a tool for a single purpose but are unable to adapt that tool to a different set of problems. An example of this would be numerous birds who use certain tools as part of foraging, but are inflexible with the same tool in other situations. This is a far cry from looking at a stick, finding a particular shape, pulling it apart, sharpening it, honing it to a point, and using it to hunt. Of the species that have been observed to use sophisticated or repetitive tools, we find that there are really five major groups: Primates, Cetaceans, Elephants, Birds, and the Octopi.
Primates -- We know chimpanzees now make weapons and hunt for prey. They have been observed for decades using sticks and reeds as probes for collecting ants and termites -- and manipulating the stick so it fits in the hole better. West African Chimpanzees use stones to open nuts, clubs to break into bee hives and stay a distance away from the angry bees. They will make sponges with leaves for grooming, use sticks to measure water distance, and when presented with a false threat (stuffed leopard, for instance), will often become agitated and make clubs and spears to kill the leopard (Cohen, 2010).
Birds -- Parrots and vultures often use rocks to open eggs or drop bones on a rock to break them. Crows use sticks, much like Chimps, to extricate ants and termites from their hole, seagulls will often drop oysters on hard surfaces to break them, and gulls will sometimes use pieces of food to bait fish. Ravens, surprisingly, are one of only a few species to make their own toys, and have been observed breaking off twigs and cloth to play socially (Emery, 2006).
Cetaceans -- Dolphins and whales have long been the subject of interspecies communication, but many have been seen using manipulatives to hunt for food. Bottlenose dolphins will often tear off pieces of sponge and wrap the sponge around their nose to protect it from abrasions while they scour the sea floor. Dolphins will also use manipulatives to both play and hunt -- for instance, they will "blow bubbles" to form rings that trap prey. The larger whales are less likely to use manipulatives due to their size, but have been shown to communicate complex location, emotion, and organizing behaviors (Krutzen, Mann, Heithaus et al., 2005).
Elephants -- Despite their size, elephants often show a remarkable ability for tool making, despite having no hands. Instead, they are quite dexterous with their trunks, using it like an arm, and the tip like a vice grip or pliers. They dig holes to drink water, will often rip off bark and shape it to cover the hole, then covering that with sand to avoid evaporation, later returning and "reopening" the cache. They use branches to swat flies, scratch themselves, or manipulate the environment. And, in areas in which farmers have an electric fence surrounding a field, elephants will often take larger rocks and drop them on the fence at straegic locations to ruin the electrical charge. We do know that elephants have been "trained" for years to help humans with logging and other taks, but it appears that elephants use this behavior in the wild. And just to prove that elephants can think beyond the present, an Indian elephant was pulling logs out of a truck to make a fence. The elephant continued to follow commands with the exception of one hole in which the elephant simply would not lower the log, but held it in mid-air. When the driver looked in the hole, he found a dog sleeping inside -- and only when the dog was chased away would the elephant place the log into the hole (Holdrege, 2001).
Octopi -- Suprisingly, octopi have been shown to use tools. The will retrieve discarded coconut shells, manipulate them, and then reassemble them to use as a makeshift shelter (Coghlan, 2009). Other octopi will use Jellyfish and Portugese Man o War tenticles that they shear as their own weapon. They are the only invertebrates known to use tools and show surprising cognitive ability in mazes, food training, and even handler recognition (Jones, 1963).
Implications - Research into this new discovery is important because it redefines what it means to be "human," as well as implications about the evolution of violence and hominid predation. Finally, an understanding of non-human "culture" may help in answers questions about other intelligent species and human interaction with them.
That the Chimpanzee tribe would be sophisticated enough to carry out a hunt with tools implies several things. First, that the Chimpanzee was aware that they would have greater success in imagining a manipulative that would assist them in a preconceived notion. They would need to imagine the way the Bushbabies hide, and then extrapolate that into finding a tool they could easily manipulate into assisting them in a particular behavior. But it is not just any manipulative that the pick, the pick the best branches that have the best shapes, strip the leaves off them, and actually sharpen the points to make them far more effective weapons than simply using a stick. In fact, these Chimpanzees completed four or more steps to manufacture their tool. They were also able to decide which side branches should be stripped off in order to strengthen the manipulative and also make it less unweildly. They are also able to determine the relative size of the tool in relation to themselves, and adjust the tool accordingly -- in other words, unlike humans, one-size tool does not fit all (Pruetz, 112).
Indeed, studies of chimpanzees show that there is less socialization bias and a predisposition towards innate vs. environmental origins, as politically incorrect as this may seem. Male and female chimpanzees, like humans, considering there is less than a 2% differentiation on our genetic structure, differ. Genetics between the sexes are different, so is anatomy, neurology, and hormonally; yet in studies of chimpanzees these differences to do not necessarily indicate a strict dictum of solid behavior from each. For example, in the wild, female chimpanzees tend to be less competitive, more nurturing, conciliatory, and supportive of older, or weaker individuals. Males are certainly more competitive to pass on their genetic structure, but also depend upon cooperation in the wild, yet continually vie for a hierarchical challenge. Male chimpanzees have different social strategies than females, and yet, when combined, their society typically functions in balance. These behaviors, extrapolated, are likely to have remained similar in proto-humans, thus giving rise to the notion that many behaviors are "wired in" or at least genetically habitual (De Waal, 2007, 195-6).
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