A rare find of Neanderthal fossils or subfossils shows that early Neanderthals were small-brained and developed larger brains independently of the line that led to us.
As best we can tell, humans and Neanderthals diverged from a common ancestor about 500,000 years ago, a species called Homo heidelbergenesis. Modern humans appeared in Africa some 300,000 years later, a time when Neanderthals were already romping around Europe and Asia.
These skulls are 430,000 years old. They have a small braincase but in other respects have Neanderthal characteristics.
…the Neanderthal trait of an elongated and rounded brain case came later.