Nerves of sponge?

The unassuming cells of a sea sponge may hold a clue to the origin of the nervous system, according to a paper published next Tuesday, August 5th, in linkurl:Current Biology.;http://www.current-biology.com/ The detection of proneural pathways in the ancient organism suggests that genes for neurogenesis evolved earlier than previously believed. Researchers have widely believed that nerve cells evolved after the divergence of sponges, which lack organs and nervous systems, from the rest of the animal kingdom (bilaterians). But linkurl:Bernard Degnan;http://profiles.bacs.uq.edu.au/Bernard.Degnan.html of the University of Queensland in Australia and colleagues detected the expression of two key components of neuronal differentiation in bilaterians, Notch-Delta signaling and basis helix loop helix (bHLH) genes, in the surface cells of the sea sponge linkurl:Amphimedon queenslandica.;http://www.the-scientist.com/news/display/53271/ "Notch signaling is the most important pathway in neurogenesis," said linkurl:Hugo Bellen,;http://flypush.imgen.bcm.tmc.edu/lab/hugo/index.html a neuroscientist at Baylor College of Medicine, who was not involved in the study. "It's...