El van Gogh oculto.

X-ray reveals mystery portrait.

Phillip Ball


An unknown Vincent van Gogh painting of a woman's head has been revealed with X-ray technology. The painting is thought to have been made in 1884–85, during a period in which he painted several portraits of peasants in the Dutch village of Nuenen. The image was hidden beneath Patch of Grass, an unrelated landscape that van Gogh painted a year or two later when living in Paris.




Earlier X-ray studies revealed a faint, blurry shadow of a figure. But Joris Dik of the Delft University of Technology in the Netherlands and his colleagues have extracted a much sharper image using the Deutsches Elektronen-Synchrotron (DESY) in Hamburg, Germany (J. Dik et al. Anal. Chem. doi:10.1021/ac800965g; 2008). The synchrotron's X-ray beam excites secondary X-rays from elements in the sample at characteristic wavelengths. The researchers mapped the distributions of cobalt, arsenic, lead and other metals in the hidden paint layers — all well-known components of pigments that were available at the time. Although the study did not identify all the pigments in the picture, it enabled the researchers to create the partial colour reconstruction shown here.

Van Gogh often re-used old canvases, partly in an effort to save money. Dik's team speculates that he took the portrait with him to Paris, where it would have seemed sombre and unfashionable in comparison to the Impressionists' works, and so he decided to paint a brighter, more commercial floral scene over it.

La dinamica de la evolucion no siempre produce los mejores organismos.

"La supervivencia del mas fuerte", "la supervivencia del mas apto", "la supervivencia de los mejores"... son variaciones todas ellas de la coda esencial de la evolucion por seleccion natural, que dice que solo los organismos mejor adaptados son los que prevalecen a expensas de aquellos que no portan rasgos adaptados para hacer frente a las presiones del entorno.

Sin embargo, un grupo de investigadores dirigidos por el doctor Matthew Cowperthwaite ha publicado un articulo en la revista de acceso publico PLOS Computational Biology que parece indicar que la evolucion por seleccion natural no siempre produce los rasgos mas optimos, o mejores, sino aquellos que son mas faciles de producir y ademas de forma abundante.

Esto parece sugerir que a largo plazo la evolucion no crea los mejores fenotipos u organismos, sino una gran cantidad de fenotipos con rasgos faciles de diseñar aunque no sean los mejores.

Abastract.
Evolution by natural selection is fundamentally shaped by the fitness landscapes in which it occurs. Yet fitness landscapes are vast and complex, and thus we know relatively little about the long-range constraints they impose on evolutionary dynamics. Here, we exhaustively survey the structural landscapes of RNA molecules of lengths 12 to 18 nucleotides, and develop a network model to describe the relationship between sequence and structure. We find that phenotype abundance—the number of genotypes producing a particular phenotype—varies in a predictable manner and critically influences evolutionary dynamics. A study of naturally occurring functional RNA molecules using a new structural statistic suggests that these molecules are biased toward abundant phenotypes. This supports an “ascent of the abundant” hypothesis, in which evolution yields abundant phenotypes even when they are not the most fit.

Articulo aqui.

Richard Thaler sobre las decisiones que nos guian en la buena direccion.

El auge de la fenomenologia en la filosofia analitica.

Via Leiter Reports.

Sean Kelly

In the second volume of her autobiography, La Force de l'age (1960), Simone de Beauvoir describes the evening in the early 1930s during the course of which Jean-Paul Sartre first became passionate about the philosophical method known as phenomenology. Raymond Aron, the young French philosopher, had been in Berlin studying the new philosophical method of Edmund Husserl (1859- 1938). On his return he joined Sartre and de Beauvoir for a drink at the Bec de Gaz in the rue Montparnasse. Beauvoir:
We ordered the specialty of the house - apricot cocktails. Aron pointed to his glass: "You see, mon petit camarade, if you are a phenomenologist, you can talk about this cocktail and make philosophy out of it!" Sartre turned pale with emotion; this was precisely what he had been longing to achieve for years - to describe objects just as he experienced them, and for that to be philosophy.
If this descriptive task really is what undergirds the phenomenological method - and there is much in favour of such a preliminary characterization - then perhaps it is not difficult to explain the notorious rift in the mid to late twentieth century between the so-called analytic and phenomenological camps in philosophy. After all, it is hard to imagine Bertrand Russell paling with emotion before an apricot cocktail. And yet, explanations by way of national character can take us only so far; perhaps we can hope for a more trenchant analysis.
Such an analysis is all the more desirable because the chasm between the camps increasingly seems to have filled itself in. This is no little feat, given how widely it once yawned. By 1958 the situation was so dire that a notorious meeting at Royaumont pitted English-speaking philosophers against their French counterparts in what the young Charles Taylor, then still a prize Fellow at All Souls, described as "a dialogue de sourds".
The determined deafness of that mid- century has now given way to healthy curiosity. Of course, even half a century ago there were books about phenomenology written in English. Herbert Spiegelberg's massive two- volume history of the phenomenological movement was published in 1960, and Fr William Richardson's equally massive volume on Martin Heidegger appeared shortly after, along with a preface by Heidegger himself. But these were attempts to explain the movement - either by a dedicated historical reconstruction of who was saying what to whom, or by an enthusiastic translation of its most prominent oracle. What is notable today, by contrast, is the desire to appropriate phenomenology, to forage among its branches for the tastiest fruit; and along with this desire, the belief - or at least a resolute openness to the possibility - that the phenomenological fruit might offer philosophical nourishment.
Not every recent contribution to the literature, of course, has this admirable, appropriative quality. Indeed, the bookstores seem to be teeming lately with synoptic overviews of Husserl and his method. David Woodruff Smith, in Husserl, one of the most recent contributions, attempts to present the whole of the philosophical work of Husserl at an introductory level. Smith moves briskly, and relatively accurately, through the various aspects of Husserl's thought; but the task he has set himself is Herculean. That is because the real contribution of Husserl's work is not systematic (though Husserl himself certainly had systematic ambitions); it lies rather in the careful and detailed analyses he provides of an enormous range of philosophical domains. The details of these analyses - often shifting over the years, frequently mistaken in interesting ways, but always probing and original - provide one basic source to which contemporary English-speaking philosophers are beginning to turn in their recent discovery of the phenomenological tradition. Despite a brief section on Husserl's legacy at the end of Smith's book, he is unable to prepare the reader for the curiosity about phenomenology that some contemporary analytic philosophers have begun to feel.
From where, then, does this curiosity come? One factor is certainly the lack of unity - or to put a positive spin on it, the pluralism - that now characterizes much anglophone philosophy. Brian Leiter, arguably the reigning sociologist of the discipline, has even announced the "demise of analytic philosophy", on the grounds that the methodological and substantive pluralism of contemporary anglophone philosophy is now so pronounced that it leaves little to demarcate as "analytic" philosophy as such. Perhaps in retrospect it is clear that this lack of unity characterized even the Oxonians at Royaumont. But at least the standard view is that analytic philosophy for much of the twentieth century was unified by the so-called linguistic turn.
There is disagreement, of course, about what the linguistic turn was, but many of the contestants may agree to at least this: that after the linguistic turn philosophy was motivated to resolve, or perhaps to dissolve, or at any rate to address, philosophical problems primarily by analysing the language we have for talking about the domain in question. Consider perception, for example. On the linguistic account, philosophical problems in this domain should be approached not by thinking primarily about the experience of perceiving, but by thinking rather about the language we have for talking about perception. To take one influential instance, Elizabeth Anscombe, writing in the mid-1960s, approached the philosophical study of perception primarily through an analysis of the grammar of verbs used for perceptual report, such as "see". This, surely, is not what paled the emotional Sartre. Indeed, one significant interpretation of the difference between phenomenology and analytic philosophy, defended most prominently by Michael Dummett, formerly Wykeham Professor of Logic at Oxford, is precisely that Husserl's method precludes such a linguistic turn.
I'll explore this claim more carefully in a moment. First, though, it is worth remarking that two distinct, though sometimes related, movements in recent English-speaking philosophy have been predicated on at least an implicit rejection of the linguistic approach. The first is in metaphysics, the second in philosophy of mind. Perhaps it is not surprising that these are the two areas of contemporary anglophone philosophy where scholars have been most eager to explore the phenomenological literature.
In metaphysics, a revival of the pre- Kantian style of a priori argument, along with renewed interest in the modal notions of possibility and necessity, pushed the most prominent English-speaking philosophers beyond the analysis of natural language in the final third of the twentieth century. According to Timothy Williamson, current holder of the Wykeham chair, and one of the leading contemporary metaphysicians, it is, rather, a "subtle interplay of logic and the imagination" that directs most of the best contemporary work. The desire to discover the essential nature of entities in any region of being (material, mental, abstract, mathematical, cultural, and so on), and to do so through thought experiments that test our intuitions about what it takes for an entity to change from what it essentially is, was also at the heart of Husserl's phenomenological method. Such thought experiments are applications of the technique Husserl calls "eidetic variation", and he believed, like many contemporary metaphysicians, that such a technique, when properly applied, gives us the capacity for "rational intuition"; for "seeing", in other words, what things essentially are. Indeed, it was this aspect of Husserl's phenomenology to which the great mathematician and logician Kurt Godel was increasingly attracted towards the end of his life. And it was the application of this technique, among others, that led to Husserl's early work on the metaphysical nature of parts and wholes, work that the eminent contemporary metaphysician Kit Fine has called "perhaps the most significant treatise on the concept of part to be found in the philosophical literature".
If metaphysicians are intrigued by phenomenology, however, it is in the philosophy of mind that it is most likely to make its mark. This is in the first place because one of the primary and most successful objects of phenomenological investigation - as exemplified by Sartre's original encounter - has been our own conscious mental states. But it is not just that phenomenology devoted itself so successfully to describing the subjective character of experience; it is also that, under the influence of the linguistic turn, anglophone philosophy neglected it so much. Indeed, despite its being a central topic of fascination for modern philosophers from Descartes to Kierkegaard, it is only in the past decade or so that the mainstream contemporary English-speaking world has rediscovered the philosophical importance of subjective experience per se.
To be fair, there were notable renegades along the way. In the mid-1970s Thomas Nagel emphasized the significance of the "subjective character of experience", and in the early 1980s John Searle argued that all mental states depend upon a pre-linguistic set of "background" capacities without which they would fail to represent anything at all. In addition, there was challenging work on the phenomenological side from Hubert Dreyfus, the eminent Heidegger scholar and leader of the American phenomenologists. (I worked with both Searle and Dreyfus as a graduate student at Berkeley.) But the decisive split with the linguistic philosophy of the twentieth century didn't enter the main- stream in philosophy of mind until 1996, with David Chalmers's influential book The Conscious Mind. Although Chalmers's work itself focused principally on traditional metaphysical issues concerning the relation between the mind and the body, the ensuing enthusiasm for problems concerning consciousness and perception stimulated an interest, among some philosophers of mind, in various non-traditional problems about the phenomenology of conscious mental states. In this context the classic phenomenological texts by Husserl and such second-generation phenomenologists as Heidegger, Sartre and Maurice Merleau-Ponty have increasingly found their way onto English-speakers'desks.
So what exactly is phenomenology, and what precisely does it have to offer? It is useful to return to Sartre. What excited him so much about the prospect of phenomenology, as we saw, is that it is devoted almost entirely to describing things. Indeed, description is so central to phenomenology in all of its phases that Heidegger could say, in one of his early lecture courses, that "the phrase descriptive phenomenology is, at bottom, tautological". Description stands in contrast to all the other things a philosopher might be doing when engaging philosophically with a given domain: causal explanation, rational reconstruction, transcendental argument, conceptual analysis, theory-building, and so on. The idea behind phenomenology is that simply describing the phenomena, as completely and accurately as possible and without importing into the description unwarranted presuppositions about how the domain described is or must be, is already a devilishly difficult project. And one can see why. If one has tacit presuppositions about what the phenomena of a given domain are like - as one is bound to with any sufficiently interesting domain - then learning to separate out the phenomena as they actually are from one's presuppositions about them will require a certain kind of discipline. The commitment to this discipline was implicit in the famous battle cry of the phenomenologists: "Zu den Sachen selbst!" ("To the things themselves!"). To get a sense for phenomenological description, let us consider again the case of perception.
Recall that perception played a particularly important role in the epistemology of early modern philosophy as it was developed by Descartes, Locke, Berkeley, Hume and others. In one form or another these empiricist philosophers all believed that we get the thoughts and ideas we have about the world directly from our more fundamental sensations of it; the thoughts are simply "less forceful and vivacious" copies of the images we receive in perception. But this epistemological position carries with it an implicit phenomenological presupposition as well. In particular, the traditional empiricist view, descendants of which have continued to be influential in the twentieth century, takes perception to be the presentation of an image before the mind, an image which can later be copied and stored as an idea. In the twentieth century such an image was often called a "sense datum". Notice that the phenomenological commitment involved in sense- datum theory already goes beyond traditional linguistic-philosophical accounts of perception, since these find the central philosophical features of perception to be discoverable through pure linguistic analysis.
Linguistic philosophers such as Wittgenstein or Anscombe needn't have denied that perceptions have some phenomenological character, of course, but their linguistic technique certainly dissuaded one from focusing on its details. And indeed, one recent position in the philosophy of mind goes so far as to deny any phenomenological features to perception at all. The phenomenologist criticizes the sense-datum theory of perception, as we will see, on the grounds that it gets the phenomenology of perception wrong. But it resists the linguistic approach in a stronger sense, along with the approach that denies any phenomenological features to perception at all, for here the disagreement concerns whether description of the detailed phenomenological character has any essential role to play in a philosophical account of perception.
Sense-datum theories did take seriously the detailed phenomenological character of perception, but different theories of sense data ascribe different phenomenological attributes to them. Still, one phenomenological commitment is common to all sense- datum theories: that the distinctive phenomenological features of the visual sense datum correlate with relevant features of the physical image cast upon the retina. Consider, for example, the much-discussed case of the penny seen at an angle. Since it casts an elliptical image upon the retina, the sense datum one is presented with in the experience of a penny at an angle is said to be elliptical. As the penny rotates towards or away from the perceiver, the retinal image of the penny, and therefore the sense datum correlated with it, changes accordingly; it becomes more or less elliptical.
In addition to this phenomenological feature, sense data are traditionally taken to have epistemological attributes as well. On Bertrand Russell's famous version of the sense-datum theory, for example, one's knowledge of sense data is taken to be "incorrigible": if I take myself to be seeing a red sense datum, for example, then I am - whether or not there is a red object in the world that is correlated with it. This incorrigibility thesis tied modern sense-datum theory back to the epistemological concerns of the early modern philosophers, and much of the discussion concerning sense-datum theories in current anglophone philosophy has focused on these kinds of incorrigibility claims. But for phenomenological purposes, the relevant issue is simpler. In particular, the phenomenologist wants to know whether it is a good description of my everyday experience that when I see a penny presented at an angle I have a perception as of ellipticality.
Husserl thought not. Indeed, Husserl observed that there is an important sense in which when I see the penny presented at an angle - at least if the angle is not too acute - it looks to be round. I can, of course, get myself into the frame of mind in which it appears elliptical - by closing one eye, for example, and focusing on the object in the way one does when trying to draw it in perspective. But it takes a special effort to see the penny in this way, and it is a mistake to think that just because the image on my retina is elliptical therefore I always experience the penny that way. It is interesting to note that there may be people who do see the world in this sense-data-like way. There is some evidence, for example, that savant artists - who are able to draw incredibly detailed scenes in perfect perspective from memory - may rely upon visual images of this projective sort. And neuroscientists have argued recently that, because of a natural misalignment of the eyes, many famous painters were unable to see in stereo. But as interesting as these extreme cases may be, they are striking to us precisely because of how unusual they are. If we are interested in the everyday experience of objects by normal perceivers then, arguably at least, Husserl was right to reject the sense-datum account.
Starting from this very simple kind of example, Husserl was able to draw out a variety of increasingly detailed and wonderful observations about the phenomena of perceptual experience. He noticed, for example, that there is an important sense in which we tend to experience objects as fully three-dimensional: in particular, they look as though they extend beyond what we can see of them from here. You can start to see this by noting that nobody is surprised, when walking around a tree, to discover that it has a backside: in some sense or another our experience of the tree from the front already involves a sense of its "voluminousness". The three-dimensionality of visual experience, however, is notoriously difficult to account for on the sense-datum view. Some sense-datum theorists, like Russell, tried to reduce the experience of voluminousness to a series of beliefs that the perceiver has about the object being perceived. But Husserl was rightly keen to resist this move. After all, I could believe that an object is a mere facade (as I might when looking at the "buildings" on a movie set) but still experience it as three- dimensional.
Husserl also highlighted the temporal dimension of experience. His most famous discussion of this phenomenon began by considering the apparently simple experience of a sequence of notes in a melody. Husserl pointed out, as many had before, that the experience of the later notes in the melody takes place (in some sense or another) against the background of an experience of the earlier notes. But he went on to show that it is exceedingly difficult to describe one's current experience of the earlier notes. In particular, one cannot say, as the sense-datum theorist must, that one hears the earlier notes, or that one has them "before the mind as an auditory image". The reason is that such an account has no obvious way to distinguish between hearing the notes in sequence as a melody and hearing them simultaneously as a chord. Husserl's detailed discussion of the sense in which I "retain" the earlier notes in my current auditory experience without actually "hearing" them is deep and important. It moves beyond Kant's idea that temporal experience is a matter of synthesizing a sequence of images, and it lays the groundwork for Heidegger's existential treatment of temporality. There are many places in Husserl's oeuvre that are inviting to the student of phenomenology, but one could do worse than to begin with the lectures On the Phenomenology of the Consciousness of Internal Time (1893-1917). Husserl's fascinating discussion there could be thought of as an extended rumination on the intuition that T. S. Eliot could only gesture at in "Burnt Norton", when he wrote that "Time present and time past / Are both perhaps present in time future, / And time future contained in time past".
Despite his great talent for describing various features of experience, there were important limitations to Husserl's phenomenology that troubled the second generation of phenomenologists. His focus on objects as we experience them led to an idealistic turn in his metaphysics that was strongly resisted by many of his most prominent students. And his related view that we should be able to bracket all our presuppositions about the world in order to focus exclusively on our experience of it - a method he called the "phenomenological reduction" - was seen by many later phenomenologists as naively optimistic. Still, his voluminous output - he produced more than 40,000 pages of detailed phenomenological description - remains a rich source of ideas for philosophers today.
That said, it is important to emphasize again that the real brilliance of Husserl's work lies more in its details than in its grand scheme. Like a talented poet, Husserl at his best is capable of uncovering aspects of human experience that ring absolutely true in his description of them, even though one has never noticed them before. His special skill lies in a kind of detailed self-reflection that is committed to honesty above all else, and perhaps it is not surprising that some of the most dedicated students of his work have found in phenomenology a religious dimension of the sort one finds in Augustine's Confessions or Pascal's Pensees. It is in the experience of working through the details of phenomenology that this religious, or perhaps poetic, dimension is most easily experienced. For phenomenology done properly requires a certain attitude or stance, a kind of preparation for encountering things as they really are. Eugen Fink, Husserl's final research assistant and sometime co-author, characterized this attitude lovingly when he said that phenomenology is "wonder in the face of the world". Merleau-Ponty thought Fink's characterization was particularly evocative, and perhaps it is appropriate to conclude with Merleau-Ponty's own moving and suggestive account:
Phenomenology's task was to reveal the mystery of the world and of reason . . . . It is as painstaking as the works of Balzac, Proust, Valery, or Cezanne - by reason of the same kind of attentiveness and wonder, the same demand for awareness, the same will to seize the meaning of the world or of history as that meaning comes into being. In this way it merges into the general effort of modern thought.

Sonrisas genuinas (sonrisas Duchenne) y la percepcion de la generosidad y la sociabilidad en las caras.

El rostro humano es un sistema simbolico-semiotico que emite señales con informacion social (y no-social tambien, como pistas de salud, enfermedad...) de forma continua.

Interpretando adecuadamente estas señales podemos obtener una gran cantidad de informacion: la edad, el genero, el atractivo, el estado emocional, los deseos, las intenciones, y otros rasgos complejos de personalidad, como la confianza o la generosidad, a partir de la estructura fisica de la cara, aunque todavia desconozcamos en que estructura fisica en concreto de la cara descansa la atribucion de la confianza.

En filosofia hay un problema epistemologico y metafisico que se llama el problema de las "otras mentes".

Este problema versa sobre si es posible conocer la mente de los demas, sus estados mentales (problema epistemologico), y si en realidad hay otras mentes (problema metafisico).

Como es obvio el problema metafisico, no es verdaderamente un problema real. Como ibamos a ser nosotros los unicos que sentimos, pensamos... Hay otras personas que piensan y sienten igual que nosotros. Es un poco solipsista pensar que mas alla de nuestra mente no hay nada.

Pero el problema epistemologico todavia sigue siendo un obstaculo. No podemos conocer que es lo que realmente puede estar pensando otra persona, "leer su mente" con total exactitud y certeza. Pero por un momento piensa en lo dificl que resultaria coordinar, identificar y resolver los probelmas de un grupo o sociedad, si realmente no tuvieramos, por aproximada o cercana que fuera, una minima idea de lo que otros estan pensando: como habria evolucionado el hombre y llegado a donde ha llegado.

Para hablar un lenguaje nos tenemos que poner de acuerdo en los referentes de nuestras palabras, para cazar tenemos que coordinar nuestros movimientos y ataques, para resolver los problemas de la comunidad y crear politica tenemos que persuadir, convencer, y esto conlleva el reconocimiento de la diferencia en los intereses, para interactuar socialmente, para enamorarnos... necesitamos hacer hermenutica social constantemente.

Este es el resumen del articulo de Marc Mehu, el experto en ciencia facial Anthony C. Little, y el gran psicologo evolucionista Robin Dunbar.

Abstract.
Although Duchenne smiles have been shown to have a social signal value, there is
limited evidence as to whether this effect generalises to most positive attributes, or whether it is restricted to a particular social domain. As opposed to non Duchenne smiles, Duchenne smiles involve the activity of facial muscles in the eye region (orbicularis oculi). The hypothesis that Duchenne and non-Duchenne smiles produce different responses in receivers was tested in a face perception experiment. People were asked to rate neutral and smiling faces on ten attributes: attractiveness, generosity, trustworthiness, competitiveness, health, agreeableness, conscientiousness, extroversion, neuroticism, and openness to experience. Results showed that the type of smile had a stronger impact on the ratings of generosity and extroversion. The difference between neutral and smiling was larger when faces showed a Duchenne than a non-Duchenne smile, though the effect of smile type on attributions of generosity appeared to be restricted to male faces. Therefore the Duchenne marker shows some specificity to judgements of altruism and sociability.

Articulo aqui.

Cita del dia.

"Para estar bien seguros, debemos sostener lo siguiente: lo que ante mis ojos aparece como blanco, debo considerarlo negro, si la jerarquía de la Iglesia lo considera así"
-Ignacio de Loyola-

Antropogenia: lo que nos hace humanos.

La pregunta qué es ser humano, qué nos hace humanos, qué nos hace únicos, o nos diferencia del resto de animales, es una pregunta filosófica arcaica hundida en los albores de aquellos tiempos en los que el ser humano empezo a cuestionarse a si mismo y lo que le rodeaba.

Pero es una pregunta filosofica que esta enredada en la utopia cognitiva de las respuestas sin (dis)solucion.

Hasta ahora.

Para Aristoteles la razon o el logos (lenguaje)y la construccion del espacio social (zoon politikon) es la diferencia, para Platon la inteligencia discursiva que nos libra de las meras apariencias del mundo sensible, de la caverna donde todos estamos encadenados... Descartes penso que era la conciencia del yo, la existencia de nuestra subjetividad mental, un reino mucho mas alla de lo material.

Podriamos recorrer los distintos pasajes de la historia de la filosofia o de las ideas, y darnos cuenta que ninguna de estas respuestas es incorrecta, pero tampaco completa y suficiente, demostrandonos lo complejo que es dar una definicion ultima de lo que hace humano a un ser humano.

No obstante, la capacidad para la cooperacion (la manipulacion del mundo social en favor de nuestros intereses), el uso de herramientas (la manipulacion del mundo fisico en favor de nuestros intereses) y el lenguaje (a veces erroneamente confundido con la racionalidad. Es posible la cognicion y el pensamiento inteligente sin palabras [Bermudez 2003]) son varios fenomenos que ningun psicologo cognitivo negaria como parte de los ingredientes de la receta humana o piezas del puzzle que nos hace ser lo que somos.

El reputado glicobiologo (la glicobiologia es el estudio de los azucares y su rol en las funciones celulares) Ajit Varki tiene una fijacion por el detalle mucho mas fino y preciso que sus predecesores, y sumandose a la larga tradicion filosofica de cuestionarse los orignes del ser humano, Varki tambien nos propone qué nos hace humanos.

Lo que nos hace humanos es la ausencia de una pequeña molecula, una version del acido sialico llamada Neu5Gc. Los seres humanos tenemos otra version, la Neu5Ac.

Esta molecula pequeña es la "GRAN" responsable de que las funciones en el cerebro humano hayan evolucionado del modo en que lo han hecho, en el preciso momento en que lo hicieron y por qué.

Esta molecula esta presente en el linaje mamifero, y por supuesto en todos los primates, excepto en el ser humano moderno.

Pero en su momento, una especie de hominido si que poseyo esta molecula. La mutacion que diferencio a nuestros ancestros comunes del ser humano moderno ocurrio hace unos 2 o 3 millones de años con el H. Erectus.

Varki trabaja con el paleontologo español Juan Luis Arsuaga (miembro del equipo descubridor del H. Antecessor) en el analisis bioquimico de los restos fosiles de Atapuerca para determinar si su teoria es valida, en la medida en que si demuestran que el H. Antecessor no tenia presente esta molecula, la antropogenia (el origen del hombre) quizas se deba a esta "gran" pequeña molecula.

La unica forma de que esta molecula este presente en el organismo humano es mediante la ingesta de carne y productos lacteos.

Pero una de las terribles consecuencias para el organismo humano de tener que tomar prestado de fuera esta molecula es que de la dieta en carne y productos lacteos (rica en esta molecula Neu5gc) nos lleva a la emergencia de tumores, enfermedades cardiovasculares ,artritis, o asma.

La leccion moralizante, o moraleja, es como siempre: una de cal y otra de arena.

Gracias a la revolucion en la dieta somos lo que somos y nuestro cerebro es como es (somos lo que comemos como diria aquel)

Pero tambien nos desprotegimos, y a diferencia del chimpanze que no tiene cardiopatias o dolencias de huesos y articulaciones, nosostros si.

Recientemente, gracias a una donacion, Varki dirigira, junto a otros cientificos (entre ellos Fred H. Gage), el nuevo centro de investigacion y educacion en antropogenia (siglas en ingles CARTA para Center for Academic Research Training in Anthropogeny).

Cita del dia.

"La ideologia politica puede corromper la mente, y la ciencia"
-E.O. Wilson-

La historia y destino del Universo segun George F. Smoot.

Neuroimagen transcultural: la cognicion dependiente de la cultura.

Examinando las funciones cognitivas de gente europea y americana (occidentales) y gente de Korea, Japon, y China (asiaticos) los investigadores Shihui Han y Georg Northoff, han encontrado substratos neuronales dependientes de la cultura.

Utilizando un enfoque denominado "neuroimagen transcultural" estos investigadores han demostrado la dependencia cultural explicita de varios de los correlatos neuronales de la cognicion humana, es decir, el bagaje cultural influye en las funciones cognitivas de alto y bajo nivel.

Los occidentales piensan de forma analitica mientras que los asiaticos piensan de forma mas holistica.

Durante una tarea de percepcion visual los americanos fueron mejores detectando estimulos mas salientes (mas llamativos) que los asiaticos, y ademas fueron menos influenciados por informacion contextual.

Estas variaciones en la cognicion y comportamiento tambien se han observado en la cognicion social (los mecanismos cognitivos que median la interacion y el comportamiento en relacion con otros).

Por ejemplo, en un juego de interaccion social, los asiaticos mostraban estar en mejor consonancia con los deseos e intenciones de su pareja de interactuacion que los americanos.

Las variaciones cognitivas y comportamentales tambien se reflejan en la clasificacion de objetos. Los chinos organizan categorias de objetos de una forma relacional. Por ejemplo, agrupan "monos" con "bananas" porque infieren y razonan que los monos comen bananas, luego agrupan "monos" y "bananas" conjuntamente.

De nuevo, las diferencias cognitivas se han podido observar en la representacion numerica, y la autoconciencia o representacion del yo.

En este ultimo campo, psicologos sociales en sus estudios de campo han ido recopilando distintas estrategias de contruccion del "yo" en funcion de la cultura.

Por ejemplo, los asiaticos tienen una nocion del "yo" mas interdependiente mientras que los americanos una nocion del "yo" mas independiente, indivdiualista y autonoma que les lleva a construir sociedades mas comunitarias para el primer caso, y mas individualistas para el segundo.

Estos investigadores con el uso tecnicas de neuroimagen para probar las diferencias culturales en los mecanismos de la cognicion, han confirmado estas observaciones hechas por los psicologos sociales.

Los occidentales son mejores en recordar palabras que describen rasgos personales (palabras que se refeiren a ellos mismos) que palabras que describen rasgos de otras personas (aunque sean cercanos a ellos como familiares, amigos etc.)
Los asiaticos recordaban las palabras para cado caso, igual de bien.


Teniendo en cuenta todos estos resultados los investigadores prueban la existencia de correlatos neuronales de la cognicion dependientes de la cultura y los contextos socioculturales.

Y presentan un nuevo enfoque, la "neuroimagen transcultural", por el cual describen los sistemas neuronales invariantes a la cultura y los sistemas neuronales sensibles a la cultura (cómo la cultura modela la anatomia funcional de multiples niveles de procesamiento cognitivo).

Del mismo modo, aportan mas datos sobre el rol de la plasticidad en la cognicion.

Articulo aqui.

Cita del dia.

"El sentido de la vida es improbabilidad estadistica a escala colosal"
-Richard Dawkins-

Las ultimas investigaciones neurotecnologicas en ESOF 2008 (Euroscience Open Forum).

Cita del dia.

"Se un filosofo pero en medio de toda tu filosofia sigue siendo un hombre"
-David Hume-

Entrevista a Jesse Prinz.

Pincha en las imagenes de Jesse Prinz (arriba a la derecha) o Will Wilkinson (abajo a la izquierda)

Cita del dia.

"Odio las citas"
-Ralph Waldo Emerson-

Economia y cerebro.

Via Mind Hacks.

Neuroeconomics

Do economists need brains?
Jul 24th 2008 | NEW YORK
From The Economist print edition

A new school of economists is controversially turning to neuroscience to improve the dismal science


FOR all the undoubted wit of their neuroscience-inspired concept album, “Heavy Mental”—songs include “Mind-Body Problem” and “All in a Nut”—The Amygdaloids are unlikely to loom large in the annals of rock and roll. Yet when the history of economics is finally written, Joseph LeDoux, the New York band’s singer-guitarist, may deserve at least a footnote. In 1996 Mr LeDoux, who by day is a professor of neuroscience at New York University, published a book, “The Emotional Brain: The Mysterious Underpinnings of Emotional Life”, that helped to inspire what is today one of the liveliest and most controversial areas of economic research: neuroeconomics.


In the late 1990s a generation of academic economists had their eyes opened by Mr LeDoux’s and other accounts of how studies of the brain using recently developed techniques such as magnetic resonance imaging (MRI) showed that different bits of the old grey matter are associated with different sorts of emotional and decision-making activity. The amygdalas are an example. Neuroscientists have shown that these almond-shaped clusters of neurons deep inside the medial temporal lobes play a key role in the formation of emotional responses such as fear.

These new neuroeconomists saw that it might be possible to move economics away from its simplified model of rational, self-interested, utility-maximising decision-making. Instead of hypothesising about Homo economicus, they could base their research on what actually goes on inside the head of Homo sapiens.

The dismal science had already been edging in that direction thanks to behavioural economics. Since the 1980s researchers in this branch of the discipline had used insights from psychology to develop more “realistic” models of individual decision-making, in which people often did things that were not in their best interests. But neuroeconomics had the potential, some believed, to go further and to embed economics in the chemical processes taking place in the brain.

Early successes for neuroeconomists came from using neuroscience to shed light on some of the apparent flaws in H. economicus noted by the behaviouralists. One much-cited example is the “ultimatum game”, in which one player proposes a division of a sum of money between himself and a second player. The other player must either accept or reject the offer. If he rejects it, neither gets a penny.

According to standard economic theory, as long as the first player offers the second any money at all, his proposal will be accepted, because the second player prefers something to nothing. In experiments, however, behavioural economists found that the second player often turned down low offers—perhaps, they suggested, to punish the first player for proposing an unfair split.

Neuroeconomists have tried to explain this seemingly irrational behaviour by using an “active MRI”. In MRIs used in medicine the patient simply lies still during the procedure; in active MRIs, participants are expected to answer economic questions while blood flows in the brain are scrutinised to see where activity is going on while decisions are made. They found that rejecting a low offer in the ultimatum game tended to be associated with high levels of activity in the dorsal stratium, a part of the brain that neuroscience suggests is involved in reward and punishment decisions, providing some support to the behavioural theories.

As well as the ultimatum game, neuroeconomists have focused on such issues as people’s reasons for trusting one another, apparently irrational risk-taking, the relative valuation of short- and long-term costs and benefits, altruistic or charitable behaviour, and addiction. Releases of dopamine, the brain’s pleasure chemical, may indicate economic utility or value, they say. There is also growing interest in new evidence from neuroscience that tentatively suggests that two conditions of the brain compete in decision-making: a cold, objective state and a hot, emotional state in which the ability to make sensible trade-offs disappears. The potential interactions between these two brain states are ideal subjects for economic modelling.

Already, neuroeconomics is giving many economists a dopamine rush. For example, Colin Camerer of the California Institute of Technology, a leading centre of research in neuroeconomics, believes that incorporating insights from neuroscience could transform economics, by providing a much better understanding of everything from people’s reactions to advertising to decisions to go on strike.

At the same time, Mr Camerer thinks economics has the potential to improve neuroscience, for instance by introducing neuroscientists to sophisticated game theory. “The neuroscientist’s idea of a game is rock, paper, scissors, which is zero-sum, whereas economists have focused on strategic games that produce gains through collaboration.” Herbert Gintis of the Sante Fe Institute has even higher hopes that breakthroughs in neuroscience will help bring about the integration of all the behavioural sciences—economics, psychology, anthropology, sociology, political science and biology relating to human and animal behaviour—around a common, brain-based model of how people take decisions.

Mindless criticism
However, not everyone is convinced. The fiercest attack on neuroeconomics, and indeed behavioural economics, has come from two economists at Princeton University, Faruk Gul and Wolfgang Pesendorfer. In an article in 2005, “The Case for Mindless Economics”, they argued that neuroscience could not transform economics because what goes on inside the brain is irrelevant to the discipline. What matters are the decisions people take—in the jargon, their “revealed preferences”—not the process by which they reach them. For the purposes of understanding how society copes with the consequences of those decisions, the assumption of rational utility-maximisation works just fine.

But today’s neuroeconomists are not the first dismal scientists to dream of peering inside the human brain. In 1881, a few years after William Jevons argued that the functioning of the brain’s black box would not be known, Francis Edgeworth proposed the creation of a “hedonimeter”, which would measure the utility that each individual gained from his decisions. “From moment to moment the hedonimeter varies; the delicate index now flickering with the flutter of the passions, now steadied by intellectual activity, low sunk whole hours in the neighbourhood of zero, or momentarily springing up towards infinity,” he wrote, poetically for an economist.

This is “equivalent to neuroeconomics’ brain scan,” notes David Colander, an economist at Middlebury College in Vermont, in an article last year in the Journal of Economic Perspectives, “Edgeworth’s Hedonimeter and the Quest to Measure Utility”. Later economists such as Irving Fisher, Frank Ramsey (who proposed a utility-measuring machine called a “psychogalvanometer”) and Friedrich von Hayek would discuss the role of the complex inner workings of the brain. Hayek cited early advances in neuroscience to explain why each individual has a unique perspective on the world.

The reason why economists in the late 19th century and much of the 20th put the rational utility-maximising individual at the heart of their models was not that they thought that economics should avoid looking into the brain, but because they lacked the technical means to do so, says Mr Colander. “Economics became a deductive science because we didn’t have the tools to gather information inductively. Now, better statistical tools and neuroscience are opening up the possibility that economics can become an abductive science that combines elements of deductive and inductive reasoning.”

The big question now is whether the tools of neuroscience will allow economics to fulfil Edgeworth’s vision—or, if that is too much to ask, at least to be grounded in the physical reality of the brain. Studies in the first decade of neuroeconomics relied heavily on active MRI scans. Economists’ initial excitement at being able to enliven their seminars with pictures of parts of the brain lighting up in response to different experiments (so much more interesting than the usual equations) has led to a recognition of the limits of MRIs. “Curiosity about neuroscience among economists has outstripped what we have to say, for now,” admits Mr Camerer.

A standard MRI identifies activity in too large a section of the brain to support much more than loose correlations. “Blood flow is an indirect measure of what goes on in the head, a blunt instrument,” concedes Kevin McCabe, a neuroeconomist at George Mason University. Increasingly, neuroscientists are looking for clearer answers by analysing individual neurons, which is possible only with invasive techniques—such as sticking a needle into the brain. For economists, this “involves risks that clearly outweigh the benefits,” admits Mr McCabe. Most invasive brain research is carried out on rats and monkeys which, though they have similar dopamine-based incentive systems, lack the decision-making sophistication of most humans.

One new technique being used by some neuroeconomists is transcranial magnetic stimulation, in which a coil held next to the head issues a low-level magnetic pulse that temporarily disrupts activity in a certain part of the brain, to see if that changes the subject’s preferences—for example, for a particular food and how much he is willing to pay for it. However, this tool, too, has only limited applicability, as it cannot get at the central temporal node of the brain where much basic reward activity takes place.

Still, Mr Camerer is confident that neuroeconomics will deliver its first big breakthroughs within five years. Likewise, Mr McCabe sees growing sophistication in neuroeconomic research. For the past four years, a group of leading neuroeconomists and neuroscientists has met to refine questions about the brain and economic behaviour. Researchers trained in both neuroscience and economics are entering the field. They are asking more sophisticated questions than the first generation “spots on brains” experiments, says Mr McCabe, such as “how these spots would change with different economic variables.” He expects that within a few years neuroeconomics will have uncovered enough about the interactions between what goes on in people’s brains and the outside world to start to shape the public-policy agenda—though it is too early to say how.

The success of neuroeconomics need not mean that behavioural economics will inevitably triumph over an economics based on rationality. Indeed, many behavioural economists are extremely pessimistic about the chances that brain studies will deliver any useful insights, points out Mr Camerer with regret.

However, Daniel Kahneman, a Princeton University psychologist who in 2002 won the Nobel prize in economics for his contribution to behavioural economics, is an enthusiastic supporter of the new field. “In many areas of economics, it will dominate, because it works,” says Mr Kahneman.

Even so, “we are nowhere near the demise of traditional neoclassical economics,” he argues. Instead, insights from brain studies may enable orthodox economists to develop a richer definition of rationality. “These traditional economists may be more impressed by brain evidence than evidence from psychology,” he says; “when you talk about biology either in an evolutionary or physical sense, you feel they have greater comfort levels than when you start to talk about psychology.”

In this respect, Mr Kahneman’s Princeton colleagues and neuroscience-bashers may be making a mistake in bundling behavioural economics—soft mind science—and neuroeconomics—hard biology—together. “It is far easier to argue for mindless economics than for brainless economics,” he says.

Sexo y cerebro.

Hay una gran cantidad de rasgos fisicos sexualmente dimorficos en el linaje primate, incluido el ser humano, es decir, rasgos que difieren en tamaño, forma, estructura y fisiologia basica segun que sexo los posea, ademas de diferencias en comportamiento reproductivo, secrecion hormonal, habilidades espaciales, verbales para el caso del ser humano etc.

En neurociencia y otras areas de la ciencia cognitiva es un debate perenne si las diferencias sexuales existentes en la cognicion (atencion, memoria,inteligencia...) se deben a factores medioambientales o geneticos (nature/nurture)

La investigadora Elena Jazin y colaboradores de la Universidad de Uppsala han investigado las diferencias existentes en la expresion genetica de una region del cerebro fundamental para la realizacion de funciones de alto nivel, o procesos cognitivos, la corteza.

Mediante un enfoque evolutivo, comparacion interespecies de cerebros femeninos y masculinos del macaco (macaca fascicularis), titi comun (Callithrix jacchus) y ser humano (homo sapiens),los investigadores, partiendo de la hipotesis de trabajo de la existencia de diferencias en la expresion genetica sexualmente dependiente y que estas diferencias son funcionalmente relevantes y altamente conservadas en la evolucion primate, hallaron en el cerebro (de las tres especies) genes especificos envueltos en la construccion de la arquitectura funcional de la corteza.

Este patron de expresion genica viene a ser seña caracteristica de la corteza cerebral (los genes principales que muestran un dimorfismo sexual en las tres especies son el XIST y el HSBP1) y conservan un paton de expresion sexualmente dimorfico en las tres especies, no encontrandose sobreexpresado en los cerebros femeninos de dichas especies.

Este trabajo, dicen los investigadores, puede arrojar luz a la psiquiatria biologica o el estudio de los genes, moleculas y sus anormalidades vistas como responsables de los desordenes psiquiatricos, porque puede aportar datos sobre la prevalencia y susceptibilidad a padecer condiciones psiquiatricas segun el sexo.

Articulo aqui

Cita del dia.

"El cerebro humano empieza a funcionar desde el momento en que naces y nunca para hasta que te pones en pie para hablar en publico"
-George Jessel-

Pintura y cerebro.

El arte se crea a partir del cerebro. Cualquier disfuncion cerebral influye en la forma en que el artista crea su imagineria y su estilo. A lo largo de la historia de la pintura no ha habido pocos casos de artistas que padeciendo desordenes en las rutas visuales (miopia, cataratas, astigmatismo)o en el cerebro per se a consecuencia de trastornos psiquiatricos (van Gogh), su arte ha alcanzado un estilo peculiar y genuino.

Renoir, Degas, Cezanne, Pissarro, Degas, Dufy, Derain, Braque, Vlaminck, Rodin, Segonzac y Matisse eran miopes (Trevor-Roper, Patrick D. 1988).


Renoir pintaba sus cuadros con mayor detalle en aquellas partes mas cercanas a él que en aquellas mas distantes, y aunqnue esto normalmente se ha interpretado como un compromiso con el manifiesto impresionista, esto realmente se puede ver como un sintoma de miopia que ademas se agudizo con el paso del tiempo. Ademas sabemos que Renoir renego de llevar gafas o lentes toda su vida.

El Greco era astigmatico. El astigmatismo caracterizado por el aplanamiento de la curvatura de las lentes, le hizo pintar sus figuras pictoricas de forma alargada (Marmor y Ravin 1997).

Monet padecia de cataratas y se sabe que las cataratas distorsionan la percepcion del color.


Munch sufio una hemorragia interna en el ojo en 1930, y experimento con drogas para testar los limites de las imagenes, y por supuesto todo ello influyo en su arte.

La pregunta que surge para cualquier aficionado o academico de la historia del arte es: hasta que punto la estragia pictorica, el estilo o la adherencia a una escuela con un manifiesto concreto es fruto deliberado del compromiso teorico o intelectual con las ideas sobre el arte, personales o culturales del momento al que se pertenece, o es fruto de los deficits cerebrales (el componente interpretativo del arte) o visuales (el componente perceptor), en definitiva, de la estructura de tus procesos cognitivos. Mas poeticamente formulada la pregunta: el artista elige su arte, o el arte le elige a él.

La imagen es de un cuadro de Milton Avery.

Habilidad locomotora en animales y robots.

Este es el resumen de un articulo original de investigacion del profesor Auke Jan Ijspeert sobre el desarrollo de patrones centralizados de actividad neuronal oscilatoria capaces de producir patrones coordinados necesarios para la lacomocion, y como del estudio de estos mecanismos biologicos en los sistemas nerviosos de los animales se puede crear robots con propiedades locomotoras biologicamente inspirados.

Abstract.

The problem of controlling locomotion is an area in which neuroscience and robotics can fruitfully interact. In this article, I will review research carried out on locomotor central pattern generators (CPGs), i.e. neural circuits capable of producing coordinated patterns of high-dimensional rhythmic output signals while receiving only simple, low-dimensional, input signals. The review will first cover neurobiological observations concerning locomotor CPGs and their numerical modelling, with a special focus on vertebrates. It will then cover how CPG models implemented as neural networks or systems of coupled oscillators can be used in robotics for controlling the locomotion of articulated robots. The review also presents how robots can be used as scientific tools to obtain a better understanding of the functioning of biological CPGs. Finally, various methods for designing CPGs to control specific modes of locomotion will be briefly reviewed. In this process, I will discuss different types of CPG models, the pros and cons of using CPGs with robots, and the pros and cons of using robots as scientific tools. Open research topics both in biology and in robotics will also be discussed.

Articulo aqui.