Nature’s Newsmaker of the Year for 2009 is Steven Chu, the Nobel-prizewinning physicist chosen by President Barack Obama as US energy secretary. Eric Hand spoke to Chu before the Copenhagen summit about his and the administration’s plans. Cover photo: Steven Chu at the US Department of Energy (Charles Ommanney/ Getty Images)

Many seemingly random or chaotic human activities have been found to exhibit universal statistical patterns. Neil Johnson and colleagues use detailed data sets from conflicts, including those in Afghanistan, Iraq and Colombia, to show that insurgent wars fit into this category, sharing common patterns with each other and also with global terrorism. The cover shows Taliban insurgents in Ghazni province, south of Kabul, in November 2006. (Credit: Veronique de Viguerie/ Edit/ Getty Images)

Most of the excitatory neurotransmissions in the central nervous system, - the events that allow neurons to 'talk' to each other - are mediated by ionotropic glutamate receptors that act by opening a transmembrane ion channel upon binding glutamate, and Eric Gouaux and colleagues this week report the crystal structure of the homotetrameric AMPA-subtype rat GluA2 receptor bound to a competitive antagonist. [Image by Alexander Sobolevsky using PyMOL (DeLano Scientific LLC)]

Three groups report crystal structures of the plant stress hormone abscisic acid (ABA) unbound and in various complexes with its receptors: a fourth paper reports the reconstitution of the ABA signalling pathway in vitro — a first for plant hormones. The cover image shows a desert primrose coping with drought. Picture credit: Alan Kearney/Getty Images.

The possibility of future decline in the Atlantic meridional overturning circulation is central to discussions of climate change. Attention has focused on the reduction in Atlantic deep-water circulation from freshwater inputs in the North Atlantic, but a new high-resolution ocean model study shows that the North Atlantic is already experiencing an opposite effect from the south, with increased transport of warm and salty Indian Ocean waters around the tip of Africa. The cover image shows temperatures and currents at 400 m depth in a high-resolution regional model, nested in a global ocean/sea-ice model. [Cover image: Toni Schröder/ IFM-GEOMAR]

The third and last of Nature’s Darwin 200 special issues marking the Darwin bicentenary focuses on biodiversity and how to preserve it. For a listing of all Darwin-related content from this issue, see the Editorial. All of this content, plus web-only material, is available at www.nature.com/darwin. [Cover: Natural History Museum, London; Artwork by Nik Spencer.]

Femtosecond stimulated Raman spectroscopy of the green fluorescent protein (GFP) chromophore reveals the molecular vibration that drives the proton transfer that lights up biologists’ favourite gene expression marker. Cover graphic: Renee Frontiera.

The cover shows colonies of the bacterium Pseudomonas fluorescens that have evolved the capacity to switch randomly between colony types, enabling them to thrive in a fluctuating artificial environment that constantly favours different colonies. This laboratory demonstration of the evolution of 'bet hedging' illustrates a strategy that may have been among the earliest evolutionary solutions to life in fluctuating environments. Cover photo: Hubertus J. E. Beaumont.