Fun archaeo-dentistry fact -
for thousands of years, most humans in wheat agriculture societies had terrible teeth because of the stone dust from millstones like this persisting into the finished bread.
until the industrial era, when we could make steel grinders.
thanks, modern steel industry!
that’s not arbitrary - the hour hand of a clock mimics the shadow of a sundial.
it makes sense, in the northern hemisphere, where 90% of people live.