I've always been a history buff. I was just curious if we knew the history of straights and shaving brushes.

Straights

1. The earliest razors are supposedly made of obsidian and flint. But the oldest actual razors that aren't rocks I guess are traced back to Egypt. Are ll razors after that derivatives of that or were copper/bronze razors invented independently? Like these Nordic Bronze Age razors





2. Where either kamisoris or straights inspired by one another? Or is the shape just a coincidence?

Shaving Brushes

1. I can't find much on the history of shaving brushes other than something about the French or Hungarians before them.

2. Taking it even one step further a shaving brush can be considered to be a modified paint brush. Does anybody know if paintbrushes were invented in multiple places or do they trace back to middle China?