The human brain may actually be two separate organs, according to a new study from Stanford scientists. The research suggests the brain develops from two distinct cellular systems, and that evolution may have fused together two ancient nervous systems with very different jobs.

The discovery also allowed researchers to grow human hindbrain neurons in the lab, a step that could open new avenues for studying brain development and disease. The findings point to a more complex evolutionary history for the human brain than previously assumed.

If confirmed, the work could reshape how scientists understand the brain's basic architecture and its origins.