Etología - Primatología - Evolución Humana - Psicología
A día de hoy, nadie duda que los grandes simios y sobre todo los chimpancés exhiben una serie de comportamientos que pueden calificarse de “inteligentes”. Pero ¿tienen una conciencia de sí mismos? ¿y de los otros? ¿y del mundo que les rodea?
Dada la dificultad de abordar la evaluación de la conciencia animal desde un punto de vista científico, se ha optado por estudiar otro tipo de comportamientos que de manera indirecta puedan proporcionarnos información sobre esta autoconciencia. La capacidad de autorreconocimiento de la propia imagen corporal sería un ejemplo ampliamente utilizado. Si una animal es capaz de reconocer el reflejo de su imagen se considera como una prueba de la conciencia de sí mismo.
A modo de ejemplo, presentamos un pequeño vídeo (http://es.youtube.com/watch?v=X6ffFtn_txo) en el que Juanito, nuestro chimpancé más joven, muestra signos inequívocos de autorreconocimiento de su imagen corporal. En procedimiento utilizado fue mostrar a Juanito su propia imagen a través de la pantalla de una cámara de vídeo. Como podréis ver en el vídeo, Juanito muestra conductas indicadoras de autorreconocimiento como: explorar partes del cuerpo inaccesibles a simple vista (boca, codo), comportamientos autodirigidos (golpearse, inspeccionarse), comportamientos extraños y exagerados, así como el reconocimiento incluso de la imagen de otros individuos de su grupo a través de la pantalla.
Esperamos que disfrutéis del video y que sirva para que todos conozcamos un poco más sobre la inteligencia y el comportamiento de los chimpancés.
Chimpanzees in Senegal make and sharpen spears with their teeth to go hunting. Like our own ancestors they have learned to use tools to kill their quarry more effectively.
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They use their colossal strength to thrust their spears into holes in trees where they suspect nocturnal bushbabies are sleeping.
Anthropologist Jill Pruetz believes she has made a landmark discovery - a species other than humans learning - and passing on - the skills to make a lethal weapon.
The generation of ideas and sharing a skill is a scientific definition of culture.
In another part of Africa a young chimp lowers himself gingerly into a cooling pool and squealing with excitement - in exactly the same way as a human child would. Apes are supposed to be afraid of water but this one is actively using the water as a tool to enjoy a dip.
In controlled laboratory experiments another chimpanzee called Judy quickly learns how to use a complex series of manoeuvres, turning wheels and pulling handles in order, to obtain a piece of fruit from a specially constructed wooden slot machine. But even more remarkably other chimps watch her success and then learn the skill themselves.
Learning by imitation is regarded as an essential skill for culture.
Apes display rudimentary traditions which could be interpreted as culture but are they really bright enough to develop a proper culture?
The apes are all stars of a new film - Ape Genius - which gives a fascinating insight into the depth of intelligence of animals who share 99 per cent of human genes. In it they reveal the skills, reasoning powers and emotions that were once thought to be uniquely human.
The stars include Koko a gorilla who understands sign language, Azy an orangutan maths champion, and Kanzi a bonobo who understands more than 3,000 words of English.
The film demonstrates that apes are more like us than we ever imagined and only the lack of a few mental skills has prevented them making the giant evolutionary development steps taken by their human cousins.
What's the little difference that makes the big difference and how big is the gap between Them and Us?, the film asks.
In west Africa Japanese researchers watch a mother care for sick two-years-old infant. She puts her paw on his forehead in exactly the way as a parent would check for a temperature in a child. As the baby chimp's life ebbs away she cares for him devotedly and when he dies she carries him around on her back for weeks almost refusing to accept that he is gone.
It is impossible to know what she is thinking but not difficult to recognise that she is stricken with grief.
"When I see the scene of the mother looking at the baby, I really recognise the emotional life of chimpanzees are so similar to us," says one of the researchers.
But if apes have the power to reason, learn skills, feel emotion and co-operate in a frenzied tree-top hunt for Colobus monkeys as chimpanzees do, why don't we have a planet of the apes?
The film reveals that although apes will co-operate to obtain food they don't have a shared commitment, they don't have the passion to urge or cheer on a tribe member and they do not have control of their emotions. They are also violent, impulsive and display deadly rivalry.
Although they can be taught to recognise symbols and words they don't have the mental capacity to contribute to a 'conversation' - and they don't make small talk. And most important of all although they can imitate, they can't teach or build on the achievements others have made - unlike more successful humans.
Their mental rocket is on the launch pad but it hasn't taken off, the film concludes.
An area of the brain involved in the planning and production of spoken and signed language in humans plays a similar role in chimpanzee communication, researchers report online on February 28th in the journal Current Biology, a publication of Cell Press.
“Chimpanzee communicative behavior shares many characteristics with human language,” said Jared Taglialatela of the Yerkes National Primate Research Center. “The results from this study suggest that these similarities extend to the way in which our brains produce and process communicative signals.”
The results also suggest that the “neurobiological foundations” of human language may have been present in the common ancestor of modern humans and chimpanzees, he said.
Scientists had identified Broca’s area, located in part of the human brain known as the inferior frontal gyrus (IFG), as one of several critical regions that light up with activity when people plan to say something and when they actually talk or sign. Anatomically, Broca’s area is most often larger on the left side of the brain, and imaging studies in humans had shown left-leaning patterns of brain activation during language-related tasks, the researchers said.
“We didn’t know if or to what extent other primates, and particularly humans’ closest ancestor, the chimpanzees, possess a comparable region involved in the production of their own communicative signals,” Taglialatela said.
In the new study, the researchers non-invasively scanned the brains of three chimpanzees as they gestured and called to a person in request for food that was out of their reach. Those chimps showed activation in the brain region corresponding to Broca’s area and in other areas involved in complex motor planning and action in humans, the researchers found.
The findings might be interpreted in one of two ways, Taglialatela said.
“One interpretation of our results is that chimpanzees have, in essence, a ‘language-ready brain,’ ” he said. “By this, we are suggesting that apes are born with and use the brain areas identified here when producing signals that are part of their communicative repertoire.
“Alternatively, one might argue that, because our apes were captive-born and producing communicative signals not seen often in the wild, the specific learning and use of these signals ‘induced’ the pattern of brain activation we saw. This would suggest that there is tremendous plasticity in the chimpanzee brain, as there is in the human brain, and that the development of certain kinds of communicative signals might directly influence the structure and function of the brain.”
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The researchers include Jared P. Taglialatela, Yerkes National Primate Research Center, Atlanta, GA, Department of Natural Sciences, Clayton State University, Morrow, GA; Jamie L. Russell, Yerkes National Primate Research Center, Atlanta, GA; Jennifer A. Schaeffer, Yerkes National Primate Research Center, Atlanta, GA; and William D. Hopkins, Yerkes National Primate Research Center, Atlanta, GA, Department of Psychology, Agnes Scott College, Decatur, GA.
Science Daily — When trying to understand someone's intentions, non-human primates expect others to act rationally by performing the most appropriate action allowed by the environment, according to a new study by researchers at Harvard University.
The work was led by Justin Wood, a graduate student in the Department of Psychology in the Faculty of Arts and Sciences at Harvard, with David Glynn, a research assistant, and Marc Hauser, professor of psychology at Harvard, along with Brenda Phillips of Boston University.
"A dominant view has been that non-human primates attend only to what actions 'look like' when trying to understand what others are thinking," says Wood. "In contrast, our research shows that non-human primates infer others' intentions in a much more sophisticated way. They expect other individuals to perform the most rational action that they can, given the environmental obstacles that they face."
The scientists studied the behavioral response of over 120 primates, including cotton-top tamarins, rhesus macaques and chimpanzees. These species represent each of the three major groups of primates: New World monkeys, Old World monkeys and apes. All three species were tested in the same way, and the results showed the same responses among the different types.
In the first experiment, the primates were presented with two potential food containers, and the experimenter either purposefully grasped one of the containers, or flopped their hand onto one of the containers in an accidental manner. For all three species, the primates sought the food container that was purposefully grasped a greater number of times than the container upon which the hand was flopped. This indicates that the primate inferred goal-oriented action on the part of the experimenter when he grasped the container, and was able to understand the difference between the goal-oriented and accidental behavior.
In the second experiment, the researchers asked if the primates infer others' goals under the expectation that other individuals will perform the most rational action allowed by the environmental obstacles. Again, the primates were presented with two potential food containers. In one scenario, an experimenter touched a container with his elbow when his hands were full, and in another scenario, touched a container with his elbow when his hands were empty.
The primates looked for the food in the container indicated with the elbow more often when the experimenter's hands were full. The primates considered, just as a human being would, that if someone's hands are full then it is rational for them to use their elbow to indicate the container with food, whereas if their hands are empty it is not rational for them to use their elbow, because they could have used their unoccupied hand.
Developmental psychologists have long understood that young children are able to engage in this type of rational action perception, but scientists have not understood if this ability is unique to human beings, or shared with other animals. This study suggests that this ability evolved as long as 40 million years ago, with non-human primates.
"This study represents one of the broadest comparative studies of primate cognition, and the significance of the findings is reinforced by the fact that these results were consistent across three different species of primates," says Wood. "The results have significant implications for understanding the evolution of the processes that allow us to make sense of other people's behavior."
The findings appear in the Sept. 7 issue of the journal of Science.
The research was funded by the National Institutes of Health, the Guggenheim, and the National Science Federation.
Note: This story has been adapted from a news release issued by Harvard University.
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