Insects, worms, vertebrates, and brachiopods all have central nervous systems, but they are organized in different ways. New research suggests that there is no common ancestor they share that had a central nervous system; it evolved separately in each group.

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Insects, worms, vertebrates, and brachiopods all have central nervous systems, but they are organized in different ways. New research suggests that there is no common ancestor they share that had a central nervous system; it evolved separately in each group.