Sept 6, 2010
By SINDYA N. BHANOO
In humans, the cerebral cortex, the tissuelike
outermost layer of the brain, is thought to play a critical role in creative
and analytical thinking.
But just how this portion of the brain
evolved has remained a mystery.
Now researchers report that something
resembling a cerebral cortex exists in the marine ragworm, a small creature
with ancient roots that has not changed in hundreds of millions of years.
The findings appear in the journal Cell.
Read a summary
'You can say that the topography is so similar that the human and worm
must come from a common ancestor,' said
Detlev Arendt, a researcher at the European Molecular Biology Laboratory
and one of the study's authors.
To conduct their study, Dr. Arendt
and his colleagues used a technique called cellular profiling to determine
what genes were turned on and off in the cells of the ragworm's brain. This
sort of profiling provides a molecular footprint for each cell.
Remarkably, the molecular footprint in certain parts of the ragworm's brain,
known as mushroom bodies, had a very similar footprint to the cerebral
The mushroom bodies are thought to control the worm's olfactory
senses, and may have helped the common ancestor of ragworms and humans to
find food while crawling across the seafloor.
'Now that we have
paved the way to study these mushroom bodies, we can try and understand what
this brain structure is doing,' Dr. Arendt said. 'What is it capable of
doing, and was it important to catching prey?'