Grajas, bebés o chimpancés

¿Quién es más inteligente? ¿cómo miden los científicos esa inteligencia? y, sobre todo, ¿cómo puede una graja aprender física cuando a mí me cuesta un mundo?

Physics? It's All the Same to Birds and Babies

By Michael Torrice
ScienceNOW Daily News
9 October 2009

Even with their tiny bird brains, rooks comprehend basic principles of physics at the same level as a 6-month-old baby—and beyond that of chimpanzees—a new study reports. But whether this understanding conveys any advantages remains an open question.

Rooks and other members of the crow family can manipulate tools and solve laboratory puzzles like those of Aesop's fables. Some scientists believe that these feats suggest the birds have a sophisticated understanding of physical principles—an understanding that allows them to solve problems they wouldn't encounter in the real world.

To further test the theory, Christopher Bird, a zoologist at the University of Cambridge in the United Kingdom, and his colleague Nathan Emery of Queen Mary, University of London, "quizzed" rooks on a basic concept of physics they call "support." The duo adapted a standard experiment: Infants and other primates know that an object will fall if something is not holding it up; they stare for longer than normal at images of a ball or banana floating in midair, for example, suggesting they know that something unusual is going on.

Rooks, it turns out, do the same. The researchers set up a peephole for the birds to peer into. (Rooks are natural peeping Toms and will spy through small holes or cracks looking for other rooks.) On the other side were images depicting eggs in various situations, both possible and impossible. Some eggs rested on a table, whereas others floated above it. In a more subtle twist, the researchers added a picture of an egg hovering in the air while its side or bottom touched the table's side.

In all of the image sets, the rooks peeked about 50% longer at the impossible pictures than they did at those with the egg properly supported by the table. Babies gradually develop similar reactions by 6 months of age, whereas chimps grasp only some parts of the concept of support without recognizing the physical impossibility of an egg "supported" by the side of a table. All of this suggests that the rooks have an understanding of even basic rules of physics that go beyond the comprehension of some primates, the scientists conclude online this week in the Proceedings of the Royal Society B.

Comparative psychologist Daniel Povinelli of the University of Louisiana, Lafayette, says he doesn't find the results that surprising. "How could [rooks] not have these interpretations?" he asks, noting that every creature must understand physical laws to survive. "How else would they know how to land on a branch?"

Bird acknowledges that many animals probably understand the basic idea of support, but he points out that the rooks seem to comprehend its nuances better than chimps do. Other researchers have reported crows solving puzzles that require knowledge of support without going through a period of trial and error. "[Rooks and crows] seem to be flexible enough to transfer these rules to novel situations," Bird says, adding that this transfer implies a more general intelligence than simply remembering physical rules.

Estáis invitados

Todos los grupos de 1º D (salvo el 9) tenéis que haber recibido una invitación para administrar este blog. Aceptadla y ya podéis empezar a publicar. Si no la habéis recibido, enviadme un correo haciéndomelo saber. En cuanto al grupo 9, sigo esperando que me envíen su email.

Curar a los ciegos

Los avances de la biotecnología es otro de los temas que nos ocupará a lo largo del año. La lista de enfermedades de origen genético es interminable y algunas de ellas podrían encontrar en la manipulación de ciertos genes una terapia efectiva. Conseguir que los ciegos vean podría ser una realidad en el futuro.

Gene Therapy Helps Blind Children See

By Jocelyn Kaiser
ScienceNOW Daily News
24 October 2009

A single injection of DNA into the eyes of four children born with a blindness-causing disease has given them enough vision to walk without help. The study, published today, confirms that if patients with this disease are given gene therapy early in life, the results can be dramatic.

Several clinical trials in the United States and Europe have been using gene therapy to treat a disease called Leber's congenital amaurosis (LCA), which affects about 3000 people in the United States. Those born with LCA start losing their sight at birth and are completely blind by age 40. Children born with one form, LCA2, have defects in a gene called RPE65 that helps the retina's light-sensing cells make rhodopsin, a pigment needed to absorb light. Without rhodopsin, the photoreceptor cells gradually die.

Two years ago, the Penn team began a small safety study of the therapy in humans with collaborators at the Children's Hospital of Philadelphia. They injected each patient's worse eye with a modified virus carrying the RPE65 gene. Early results from this trial and a similar study in the United Kingdom published in April 2008 showed that four of six young adults with LCA2 who received the treatment could later sense more light and perform better in an obstacle course.

But the Penn researchers knew from their studies in animals that children should improve even more because they have more intact retinal tissue than adults do. Today in an online paper in The Lancet, their team and collaborators in Europe report full study results for three of the adults they treated earlier and nine more patients, including four children ages 8 to 11. The children gained more light sensitivity than the adults did--their light sensitivity increased as much as four orders of magnitude, versus one--and they made far fewer mistakes in an obstacle course.

The LCA2 trials are a rare success for the field of gene therapy, which has also cured children with the immune disorder known as bubble boy disease. And they should pave the way for treating more vision disorders. "It's an incredible launching pad to be able to target other diseases," says Penn gene therapy researcher Jean Bennett, who led the study.

Re: ¿para qué sirve el apéndice?

Una pregunta que siempre surge al hablar de evolución es por qué seguimos teniendo apéndice si no sólo es inútil sino que, debido a la alta incidencia de casos de apendicitis, podría considerarse altamente perjudicial. Este artículo recién publicado en Journal of Evolution parece aportar luz al enigma.

Evolution:

Not So Useless

Caroline Ash

For humans, the value of having an appendix seems to be negligible and, given the prevalence of appendicitis, having an appendix can even be dangerous. This gut attachment has long been thought to be a remnant of the time when hominids ate a high proportion of plant matter that needed fermentation before digestion. More recently, the appendix has been proposed to play a role in the immune-mediated maintenance of symbiotic bacteria in the gut. On the basis of comparative anatomical and phylogenetic approaches, Smith et al. now contend that the appendix is a specialized organ for harboring symbiotic bacteria essential for health. Diarrhea was a common hazard during hominid evolution. Because the opening to the appendix is constricted, it may escape colonization by bacterial pathogens. Bacterial symbiont reconstitution after diarrhea can be achieved rapidly from the populations harbored in the appendix. Thus, far from being useless, positive selection may well have acted to maintain the appendix.

J. Evol. Biol. 22, 1984 (2009).

primera foto

Como siempre lo más difícil fue la preparación. Los frailecillos, a pesar de su aspecto, no son tontos y no tenían ninguna intencion de colocarse formando un círculo perfecto ni de mirar cada uno hacia un punto distinto. A pesar de todo, el resultado me gusta.

galerías fotográficas

Ya nos contarán Mar, Álvaro, Rocío y Jose cómo crear nuestra galería fotográfica, mientras tanto podéis ir escogiendo vuestras mejores fotografías y poniéndolas en este blog. Dejemos las fotos familiares para otros ámbitos, olvidemos a los amigos y centrémonos en temas más cercanos a esta asignatura como la naturaleza, la tecnología o el medio ambiente. Si alguno tiene inquietudes artísticas en este campo también puede publicar sus obras, aunque en ese caso, todos agradeceríamos una breve explicación sobre lo que estemos viendo.

¿para qué?

Son tantas las posibilidades que nos brinda Internet que es fácil que las perdamos la pista. La única solución es permanecer atentos, enterarnos de aquellas cosas que empiezan a imponerse, probarlas y decidir si son útiles para nosotros.
En esta parte de la asignatura estamos repasando un buen número de esas utilidades. Vosotros sois los protagonistas; exploráis, seleccionáis y nos contáis lo que habéis descubierto.
Este blog sólo pretende ser el punto de encuentro donde todos los que formáis primero D publiquéis los contenidos básicos de cada una de vuestras exposiciones y la prueba objetiva que tenéis que elaborar.
También me gustaría que lo utilizáseis para compartir esos artículos, videos, fotos, páginas web, podcasts, blogs... que, estando relacionadas con esta asignatura, puedan resultar interesantes para todos.

EN MARCHA

Hoy estrenamos este blog. En una próxima entrada explicaremos la utilidad que queremos darle.