Tiny sea creatures upend notion of how animals’ nervous systems evolved

Amy Maxmen in Nature:

A study of some of the world’s most obscure marine life suggests that the central nervous system evolved independently several times — not just once, as previously thought¹.

The invertebrates in question belong to families scattered throughout the animal evolutionary tree, and they display a diversity of central nerve cord architectures. The creatures also activate genes involved with nervous system development in other, well-studied animals — but they often do it in non-neural ways, report the authors of the paper, published on 13 December in Nature.

“This puts a stake in the heart of the idea of an ancestor with a central nerve cord,” says Greg Wray, an evolutionary developmental biologist at Duke University in Durham, North Carolina. “That opens up a lot of questions we don’t have answers to — like, if central nerve cords evolved independently in different lineages, why do they have so many similarities?”

More here.