Selección del "Complexity Digest"

Irremediable Complexity?, Science

Excerpt: Many of the cell's macromolecular machines appear gratuitously complex, comprising more components than their basic functions seem to demand. How can we make sense of this complexity in the light of evolution? One possibility is a neutral ratchet-like process described more than a decade ago, subsequently called constructive neutral evolution. This model provides an explanatory counterpoint to the selectionist or adaptationist views that pervade molecular biology.

• Source: Irremediable Complexity?, Michael W. Gray, Julius Lukeš, John M. Archibald, Patrick J. Keeling, and W. Ford Doolittle, DOI: 10.1126/science.1198594, Science Vol. 330 no. 6006 pp. 920-921, 2010/11/12

Denis Dutton: A Darwinian theory of beauty, TED.com

About this talk: TED collaborates with animator Andrew Park to illustrate Denis Dutton's provocative theory on beauty -- that art, music and other beautiful things, far from being simply "in the eye of the beholder," are a core part of human nature with deep evolutionary origins.

• Source: Denis Dutton: A Darwinian theory of beauty, TED.com, 2010/11
• VIDEO - Watch this talk

Life is physics: evolution as a collective phenomenon far from equilibrium, arXiv

Excerpt: Evolution is the fundamental physical process that gives rise to biological phenomena. Yet it is widely treated as a subset of population genetics, and thus its scope is artificially limited. As a result, the key issues of how rapidly evolution occurs, and its coupling to ecology have not been satisfactorily addressed and formulated. The lack of widespread appreciation for, and understanding of, the evolutionary process has arguably retarded the development of biology as a science, with disastrous consequences for its applications to medicine, ecology and the global environment. This review focuses on evolution as a problem in non-equilibrium statistical mechanics (...)

• Source: Life is physics: evolution as a collective phenomenon far from equilibrium, Nigel Goldenfeld and Carl Woese, arXiv:1011.4125, 2010/11/18

Selección de "Noticias Complejas"

What Is Epigenetics?, Science

Excerpt: The cells in a multicellular organism have nominally identical DNA sequences (and therefore the same genetic instruction sets), yet maintain different terminal phenotypes. This nongenetic cellular memory, which records developmental and environmental cues (and alternative cell states in unicellular organisms), is the basis of epi-(above)"genetics.

• Source: What Is Epigenetics?, Guy Riddihough and Laura M. Zahn, DOI: 10.1126/science.330.6004.611, Science Vol. 330. no. 6004, p. 611, 2010/10/29
• VIDEO - What Is Epigenetics?

Is Life Impossible? Information, Sex, and the Origin of Complex Organisms, Evolution

Excerpt: The earliest organisms are thought to have had high mutation rates. It has been asserted that these high mutation rates would have severely limited the information content of early genomes. This has led to a well-known “paradox” because, in contemporary organisms, the mechanisms that suppress mutations are quite complex and a substantial amount of information is required to construct these mechanisms. The paradox arises because it is not clear how efficient error-suppressing mechanisms could have evolved, and thus allowed the evolution of complex organisms, at a time when mutation rates were too high to permit the maintenance of very substantial amounts of information within genomes. Here, we use concepts from the formal theory of information to calculate the amount of genomic information that can be maintained. (...)

• Source: Is Life Impossible? Information, Sex, and the Origin of Complex Organisms, Joel R. Peck, David Waxman, DOI: 10.1111/j.1558-5646.2010.01074.x, Evolution Volume 64, Issue 11, pages 3300�"3309, 2010/11

A map of human genome variation from population-scale sequencing, Nature

Excerpt: The 1000 Genomes Project aims to provide a deep characterization of human genome sequence variation as a foundation for investigating the relationship between genotype and phenotype. Here we present results of the pilot phase of the project, designed to develop and compare different strategies for genome-wide sequencing with high-throughput platforms.

• Source: A map of human genome variation from population-scale sequencing, The 1000 Genomes Project Consortium, DOI: 10.1038/nature09534, Nature 467 , 1061"1073, 2010/10/27

Diversity of Human Copy Number Variation and Multicopy Genes, Science

Excerpt: Copy number variants affect both disease and normal phenotypic variation, but those lying within heavily duplicated, highly identical sequence have been difficult to assay. By analyzing short-read mapping depth for 159 human genomes, we demonstrated accurate estimation of absolute copy number for duplications as small as 1.9 kilobase pairs, ranging from 0 to 48 copies. (...) These data identify human-specific expansions in genes associated with brain development, reveal extensive population genetic diversity, and detect signatures consistent with gene conversion in the human species. Our approach makes ~1000 genes accessible to genetic studies of disease association.

• Source: Diversity of Human Copy Number Variation and Multicopy Genes, Peter H. Sudmant, et al., DOI: 10.1126/science.1197005, Science Vol. 330. no. 6004, pp. 641 - 646, 2010/10/29

Genome size, self-organization and DNA's dark matter, Complexity

Abstract: Chromosomes exhibit several features indicating that its spatiotemporal dynamics is self-organized. It has been recently suggested that a negative correlation between genome size and mean chromosome number would also be a fingerprint of selforganization, related to how human language is organized at the level of words and syllables. However, the vast dominance of non-coding DNA in eukaryotic genomes should prevent an interpretation of genome/chromosome size based on functional trade-offs related to information storage and transmission. Moreover, the reported negative correlation is shown to be an inevitable consequence of the definitions of chromosome and genome length and it is thus unrelated to any type of special generative process.

• Source: Genome size, self-organization and DNA's dark matter, Ricard V. Solé, DOI: 10.1002/cplx.20326, Complexity Volume 16, Issue 1, pages 20"23, 2010/09-10

The Origins Of Modern Biodiversity On Land, Phil. Trans. B

Excerpt: Comparative studies of large phylogenies of living and extinct groups have shown that most biodiversity arises from a small number of highly species-rich clades. To understand biodiversity, it is important to examine the history of these clades on geological time scales. This is part of a distinct phylogenetic expansion view of macroevolution, and contrasts with the alternative, non-phylogenetic equilibrium approach to the history of biodiversity. The latter viewpoint focuses on density-dependent models in which all life is described by a single global-scale model, and a case is made here that this approach may be less successful at representing the shape of the evolution of life.

• Source: The Origins Of Modern Biodiversity On Land, M. J. Benton - mike.bentonbristol.ac.uk, DOI: 10.1098/rstb.2010.0269, Phil. Trans. R. Soc. B, 2010/11/27:558, 3667-3679