jueves, 19 de febrero de 2009

Ese es medio zurdito

Why Are Some People Left-Handed? An Evolutionary Perspective,Phil. Tran. Biol. Sc.

Excerpts: Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. (...) Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. (...) We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. (...)

martes, 17 de febrero de 2009

Y como no todo es sobre Darwin...

...(no directamente por lo menos.) Un compilado del Complexity Digest:

How The Spider Spun Its Web: ‘Missing Link' In Spider Evolution Discovered, ScienceDaily

Excerpts: New interpretations of fossils have revealed an ancient missing link between today's spiders and their long-extinct ancestors. The research (...) may help explain how spiders came to weave webs. The research focuses on fossil animals called Attercopus fimbriunguis. While modern spiders make silk threads with modified appendages called spinnerets, the fossil animals wove broad sheets of silk from spigots on plates attached to the underside of their bodies. Unlike spiders, they had long tails. (...) caused the paleontologists to reinterpret their original findings. (...)


Historical and Philosophical Perspectives on Contemporary Biology, PLoS Biol

Excerpt: The work of historians and philosophers of science has long benefited from conversations with practicing scientists, but to many scientific researchers, perhaps especially to those engaged in laboratory work, the value that such dialogue might have for their own endeavor is not nearly so obvious. There are of course exceptions, evolutionary biology, for one. Over the last several decades, a tradition of active engagement between historians and philosophers on the one hand, and evolutionary biologists on the other, has become well established (...)


Where Bacteria and Languages Concur, Science

Excerpt: Two articles in this issue mark a substantial advance in our understanding of human population history in the Pacific area. On page 479, Gray et al. (1) report a computational linguistic analysis that offers a detailed and precise scenario for the dispersal and development of the Austronesian languages, and by implication of human populations among the Pacific islands. The authors come down decisively in favor of one of the two major models for the peopling of the Pacific. On page 527, Moodley et al. (2) come to the same conclusion as Gray et al. about the source and trajectory of spread of the human populations in question, based on results from a seemingly unrelated field: the archaeogenetics of human gastric bacterial parasites.


Is Genetic Evolution Predictable?, Science

Abstract: Ever since the integration of Mendelian genetics into evolutionary biology in the early 20th century, evolutionary geneticists have for the most part treated genes and mutations as generic entities. However, recent observations indicate that all genes are not equal in the eyes of evolution. Evolutionarily relevant mutations tend to accumulate in hotspot genes and at specific positions within genes. Genetic evolution is constrained by gene function, the structure of genetic networks, and population biology. The genetic basis of evolution may be predictable to some extent, and further understanding of this predictability requires incorporation of the specific functions and characteristics of genes into evolutionary theory.


The evolution and distribution of species body size, arXiv

Abstract: The distribution of species body size within taxonomic groups exhibits a heavy right-tail extending over many orders of magnitude, where most species are significantly larger than the smallest species. We provide a simple model of cladogenetic diffusion over evolutionary time that omits explicit mechanisms for inter-specific competition and other microevolutionary processes yet fully explains the shape of this distribution. We estimate the model's parameters from fossil data and find that it robustly reproduces the distribution of 4002 mammal species from the late Quaternary. The observed fit suggests that the asymmetric distribution arises from a fundamental tradeoff between the short-term selective advantages (Cope's rule) and long-term selective risks of increased species body size, in the presence of a taxon-specific lower limit on body size.


A Neandertal Primer, Science

Excerpt: The rough draft of the Neandertal nuclear genome may usher in a brave new world of research on these extinct humans, but after 150 years of study, we already know a few things about them.

  • Source: A Neandertal Primer, Michael Balter, DOI: 10.1126/science.323.5916.870, Science Vol. 323. no. 5916, p. 870, 2009/02/13

Especial Darwin 200/150

Comienzan las conmemoraciones, reflexiones y festejos (Happy birthday Charly!).

A continuación algunos enlaces para empezar a palpitar el Año Darwiniano:


The Year of Darwin, Science

Excerpt: Science is celebrating the 150th anniversary of the publication of Charles Darwin's On the Origin of Species and the 200th anniversary of the author's birth with a variety of news features, scientific reviews and other special content, all collected here.


Darwin 200: The other strand, Nature

Editor's Note: This article discusses cultural evolution, and how genes are not sufficient to understand how humanity evolved.
Excerpt: Barely a decade after Charles Darwin published On the Origin of Species, he and his long-time correspondent Alfred Russel Wallace were engaged in a fierce debate. Darwin said that natural selection had shaped the human species just like any other. But Wallace disagreed, arguing that selection alone could not account for the exceptional capabilities of the human mind. "How could natural selection, or survival of the fittest in the struggle for existence, at all favour the development of mental powers so entirely removed from the material necessities of savage men?"


Humanity and evolution, Nature

Excerpt: Although history is not made entirely, or even mostly, by prominent men and women, two great exceptions to that rule were born exactly 200 years ago today, on 12 February 1809: Charles Darwin and Abraham Lincoln.
See Also: Darwin 200 online collection.


Big Year For Darwin, But What Would He Make Of The Climate Change Ahead?, ScienceDaily

Excerpts: Charles Darwin may have been born 200 years ago come Feb. 12, but his theory of evolution remains an everyday touchstone for modern biologists. And while the Origin of Species author might not have known the term "global warming," he wouldn't have been surprised that the environment is changing. He would, however, be astonished by the speed at which it's happening today, researchers believe. "Every species is under temporary permanence," says (...). Darwin would have predicted changes in species' habits and even changes in the environment, but the planet's facing changes that are both drastic and unpredictable. (...)


Darwin 200, Nature

Excerpt: The 200th anniversary of the birth of Charles Robert Darwin falls on 12 February 2009. Darwin was arguably the most influential scientist of modern times. No single researcher has since matched his collective impact on the natural and social sciences; on politics, religions, and philosophy; on art and cultural relations, and in ways that the man himself would never have imagined.