( d which endow every type of neuron wit...)The origin of the brain lies in a worm

"Our findings were overwhelming," says Alexandru Denes, who carried out the research in Arendt's lab. "The molecular anatomy of the developing CNS turned out to be virtually the same in vertebrates and Platynereis. Corresponding regions give rise to neuron types with similar molecular fingerprints and these neurons also go on to form the same neural structures in annelid worm and vertebrate."

"Such a complex arrangement caould not have been invented twice throughout evolution, it must be the same system," adds Gáspár Jékely, a researcher from Arendt's lab, who contributed essentially to the study. "It looks like Platynereis and vertebrates have inherited the organisation of their CNS from their remote common ancestors."

The findings provide strong evidence for a theory that was first put forward by zoologist Anton Dohrn in 1875. It states that vertebrate and annelid CNS are of common descent and vertebrates have turned themselves upside down throughout the course of evolution.

"This explains perfectly why we find the same centralised CNS on the backside of vertebrates and the bellyside of Platynereis," Arendt says. "How the inversion occurred and how other invertebrates have modified the ancestral CNS throughout evolution are the next exciting questions for evolutionary biologists."