Charles Darwin's theory of descent with modification by means of natural selection has stood the test of time, with new discoveries in genetics and the mathematical basis of natural selection providing ever growing evidence for the theory. This focus issue of Nature Reviews Neuroscience — sponsored by the Wellcome Trust — celebrates the contribution of Darwin's ideas to our current understanding of the evolution of the nervous system. The articles in this special issue discuss the molecular, cellular and structural changes that have contributed to CNS evolution and their functional consequences.
Reviews
The origin and evolution of synapses
Tomás J. Ryan & Seth G. N. Grant
doi:10.1038/nrn2717
Nature Reviews Neuroscience 10, 701-712 (2009)
Tracing the phylogeny of the molecular components of synapses, Ryan and Grant speculate on the core components of the last common ancestor of all synapses and posit that the diversification of upstream signalling components contributed to increased signalling complexity later in evolution.
Considering the evolution of regeneration in the central nervous system
Elly M. Tanaka & Patrizia Ferretti
doi:10.1038/nrn2707
Nature Reviews Neuroscience 10, 713-723 (2009)
What allows some species, but not others, to regenerate their nervous system? In this Review, the authors compare CNS regeneration among vertebrates looking for clues that might explain how this ability might have emerged or been restricted through evolution.
Evolution of the neocortex: a perspective from developmental biology
Pasko Rakic
doi:10.1038/nrn2719
Nature Reviews Neuroscience 10, 724-735 (2009)
Focusing on mammalian species, Pasko Rakic uses evo–devo studies to model how gene mutations may have affected neuron number and neuronal migration, which in turn may have contributed to the species-specific expansion and elaboration of the cerebral cortex.
Chordate roots of the vertebrate nervous system: expanding the molecular toolkit
Linda Z. Holland
doi:10.1038/nrn2703
Nature Reviews Neuroscience 10, 736-746 (2009)
By comparing developmental gene expression and neuroanatomy of vertebrates and the basal chordate amphioxus, Linda Holland sheds light on the molecular changes that may have facilitated the evolution of the vertebrate brain.
Perspectives
Sleep viewed as a state of adaptive inactivity
Jerome M. Siegel
doi:10.1038/nrn2697
Nature Reviews Neuroscience 10, 747-753 (2009)
In this provocative Perspective, Jerry Siegel shows that many aspects of sleep differ greatly between species and conditions, such that a universal, vital function of sleep is unlikely. He argues that sleep benefits animals simply by increasing the efficiency of their activity.
MicroRNAs tell an evo–devo story
Kenneth S. Kosik
doi:10.1038/nrn2713
Nature Reviews Neuroscience 10, 754-759 (2009)
MicroRNAs have crucial regulatory roles at the post-transcriptional level and are emerging as key players in the development of the nervous system in many species. In this Opinion article, Kosik discusses how these non-coding transcripts could drive evolutionary change.