Oh, so you’ve heard of this thing called “science” before?
We can get some idea of what their brains looked like based upon imprints left on the inside of the skull. We can get an idea of relative intelligence based on artifacts, like tools and art. If you know that cranial volume dropped, but you can see imprints indicating more folds, and you can see cave art indicating more sophisticated culture, and more advanced tools, then you know with reasonable certainly that you’re looking at a more intelligent creature despite the smaller brain.
This is just an educated guess. No one really knows why it happened. All we have is a handful of fossilized skulls to base this on.
While I’ll take their educated guess over my own musings, that doesn’t mean they’re absolutely correct. No one knows for certain.
Oh, so you’ve heard of this thing called “science” before?
We can get some idea of what their brains looked like based upon imprints left on the inside of the skull. We can get an idea of relative intelligence based on artifacts, like tools and art. If you know that cranial volume dropped, but you can see imprints indicating more folds, and you can see cave art indicating more sophisticated culture, and more advanced tools, then you know with reasonable certainly that you’re looking at a more intelligent creature despite the smaller brain.
Has anyone thought of asking evolution? Its a theory not a guess.