I just discovered retrospectacle, a blog by a neuroscience graduate student. She has a variety of good posts like in her “Science Vault” series (Multi-nippled sheep of Alexander Graham Bell, Coffee as treatment for the Plague) as well as in general, but the post I wanted to point you toward has a bit on ancient Egyptian medical understandings of neurological disorders at the bottom.
Reading about things like that makes me appreciate cultural ratchets like databases a whole lot. Sometimes gaining knowledge is surprisingly cheap and can be done without the aid of modern technology (although not necessarily easily). But it’s pretty easy to lose, and then people keep spending time rediscovering it.
A more problematic aspect of the same issue, of course, is that without a cultural ratchet, we can’t keep track of all the knowledge we keep discovering that is inaccurate. So we invent and disprove and invent and disprove the same mistaken but attractive notions again and again throughout history. And again and again within an individual culture, if we don’t have a way of spreading that knowledge.