India, Sept. 19 -- In a paradigm-shifting revelation that upends centuries of neurological consensus, researchers at Stanford Medicine have discovered that the human brain is not a single, unified organ, but rather two distinct biological systems that evolved independently over 500 million years.

Published in the journal Nature Neuroscience, the landmark study demonstrates that the front and back of the human brain originate from completely separate developmental pathways, sharing no common progenitor cells during embryonic growth.

For generations, the prevailing dogma among neuroscientists held that the brain developed from a single, homogeneous population of progenitor cells early in embryogenesis, radiating outward to form the variou...