Abstract:

The origin of the nervous system remains one of the most exciting and unsolved questions in animal evolution. How and in what animals did the first neurons come into place? And how did animals progress from a simple nerve net, as is still observed in some marine animals such as jellyfish, to the most complex centralized nervous systems and brains, as found for instance in octopus or human?  And what were the behaviours requiring and driving this complexification?

In recent years, the molecular characterization of neurodevelopment and the sequencing and comparative analysis of cell types in a variety of organisms has yielded compelling new insights into nervous system evolution. Our laboratory is working on several marine animal model systems that are especially suited to infer ancestral states of nervous system complexity: sponges, sea anemone, annelid, amphioxus, lamprey and shark. In my lecture, I will focus on recent results from the marine annelid Platynereis dumerilii to unravel ancestral features that existed in the famous ancestor of animals with bilateral symmetry, the urbilaterian, and discuss first insight into the step-wise emergence of nervous system centralization.