The human brain has been found to be two distinct organs that evolved independently over millions of years.
A research team, led by Stanford Medicine, said it was previously believed that a single “progenitor cell” gave rise to the entire brain.
This model suggested all parts of the brain shared a common developmental origin.
The new research shows that the brain actually consists of “two ancient nervous systems cleverly packaged together”.
The first part regulates basic functions like heartbeat and breathing.
The second is the more complex area that makes us “distinctly human” and capable of “poetry, mathematics and wondering about our own origins”.
“The discovery could help explain why scientists have struggled for decades to grow certain types of brain cells in the laboratory,” a study report by Stanford Medicine said.
“It opens new avenues for studying devastating diseases that affect the brain stem, such as spinal muscular atrophy (also known as SMA) and amyotrophic lateral sclerosis (also known as ALS or Lou Gehrig’s disease).”
The study, led by associate professor of developmental biology Kyle Loh, and supported by Carolyn Dundes and Rayyan Jokhai, was published in the latest Nature Neuroscience journal
“We’ve shown for the first time that the front of the brain arises from a totally different progenitor cell than the back of the brain,” Dr Loh said.
“Our discovery means that we can now grow neurons from the back of the brain, the hindbrain, in a petri dish and study their functions.”
The researchers reviewed more than 550 million years of species evolution.
They found the same two-origin brain pattern in chickens, zebrafish and acorn worms living on the ocean floor.
“Our research suggests that evolution took two existing neural systems and pushed them together spatially,” Dr Loh said.
“Having the brain as one organ would probably be more efficient, but we rely on this primordial way to make the brain as two separate pieces.”
The full research report is The Conversation
