miércoles, 23 de noviembre de 2011

Dissecting the Cave Lion Diet



To figure out what these lions hunted, biogeologist Hervé Bocherens and colleagues at the University of Tübingen in Germany, analyzed bone samples from 14 cave lions—found in four caves in France and central Europe—that lived between 12,000 and 40,000 years ago. The team focused on the chemical content of the bone collagen, which is often well-preserved, even in bones tens of thousands of years old. By incinerating a tiny fragment of preserved bone—usually less than a milligram—researchers can identify the molecules inside it and determine an animal's diet.

Scientists have perfected the technique over the years. It was used recently to look at the diet of Neandertals, but this is one of the first studies to use it to look at a nonhuman predator—and the analysis is now sensitive enough to look several steps down the food chain. This enabled Bocherens to determine not only what cave lions ate but also what their prey ate. And that made it possible to tell, for example, whether lions were targeting full-size cave bears or their more vulnerable cubs, because adults and babies eat different diets themselves. "There's a difference between the [chemical] signal of adults and babies," Bocherens says. "Babies drink the milk of the mother."

As it turned out, this distinction was important. Bocherens's analysis, reported in the 6 December issue ofQuaternary International, revealed that the cave lions occasionally ate bear cubs but not adults. Their favorite food, however, was reindeer, which Bocherens and his team determined consumed massive quantities of lichen, much as their modern descendants did. The cave lion diet, Bocherens says, appears to have been much more finicky than that of today's lions, which eat just about anything they can catch.

martes, 22 de noviembre de 2011

Vacas, cerdos, guerras y brujas


E agora un pouco de antropoloxía con Marvin Harris. Este libro sorprendeume gratamente e quero recomendar a sua lectura a tutti. O autor, Marvin Harris, trata de explicar algunhas das costumes máis extrañas da sociedadea partire de bases materiais e económicas.
¿Porque os hindus consideran as vacas sagradas? ¿Porque os xudeos e musulmáns non comen cerdo? ¿Podemos dar unha resposta a aparición do machismo, das guerras, da volencia e consumismo actual estudando tribus primitivas que a simple vista teñen costumes que parecen irracionais? ¿Existe algunha relación entre as bruxas e as tradicións mesiánicas?
As explicacións que ofrece Harris son moi interesantes e polémicas, por iso me gustou tanto o libro, a pesar de todo sempre trata de buscar explicacións racionais os diferentes estilos de vida que trata no libro, o cal me leva a famosa frase: "consistency is better than true"

miércoles, 16 de noviembre de 2011

El gen egoísta e El relojero ciego


Hola Rapaces,

Aqui van un par de libros de divulgación científica escritos por Richard Dawkins sobre a evolucion, son El gen egoísta e a sua continuación El relojero ciego.

Ambos libros están escritos de forma amena e deixando moi claras as bases sobre as cales se apoya a teoría da evolución. En ambos libros trata con moito detalle a función do azar na evolución das especies, xa que este punto suele ser motivo de bastante confusión sobre para os que somo profanos no campo da evolución. Por exemplo esta afirmación (errónea) de Sir Fred Hoyle: “Tengamos en un desguace las piezas necesarias para construir un Boeing 747, desmontadas y desordenadas. Entonces llega un tornado y atraviesa la zona. ¿Cuál es la posibilidad de que después nos encontráramos allí el avión completamente montado y listo para volar?”. La probabilidad de este suceso, es la misma –o incluso mayor- de la que el ADN se formara de manera casual”. Esta mesma frase sería repetida por un premio novel de medicina con respecto o posible orixen do cerebro como órgano complexo formado por selección natural. Se queredes saber onde falla o argumento do 747 recoméndovos leer os libritos!

Enjoy!