Stories
Human Brain May Have Evolved as Two Independent Organs, Study Suggests
- •A new study challenges the prevailing theory of a single progenitor cell giving rise to the entire brain, suggesting the human brain evolved as two independent organs.
- •Researchers at Stanford University found the brain consists of two ancient nervous systems: a primitive part for automatic functions and another for uniquely human capabilities.
- •These two systems develop in parallel, with their cells never intersecting or overlapping, according to findings published in Nature Neuroscience.
- •The discovery could explain difficulties in growing hindbrain neurons in labs, hindering research into diseases like spinal muscular atrophy and amyotrophic lateral sclerosis.
- •Two distinct progenitor cells, expressing 'Otx2' for the forebrain/midbrain and 'Gbx2' for the hindbrain, were identified, confirming their separate developmental paths.
Key Questions Answered
Researchers discovered that the human brain may have evolved as two independent organs rather than from a single progenitor cell. The study shows that the brain consists of a primitive system regulating automatic functions like breathing and heartbeat packaged together with a system capable of higher-level thinking, with cells from the two systems running parallelly and never intersecting.
Scientists identified two different brain progenitor cells during gastrulation. One cell population expresses the gene 'Otx2' and forms the forebrain and midbrain, while another expresses the gene 'Gbx2' and is committed to forming the hindbrain. These two cell populations are mutually exclusive and never overlap from the earliest stages of development.
Previous attempts to grow hindbrain neurons likely failed because researchers tried to coax forebrain and midbrain progenitors into hindbrain cells, which is not possible due to fundamentally different chromatin configurations that lock each cell into its respective fate. This discovery now allows scientists to properly grow neurons from the hindbrain in a petri dish to study diseases like spinal muscular atrophy and amyotrophic lateral sclerosis.
