Periods are the shedding of the uterine lineing when an egg is not fertilised.
They can occur on any day of the month.
yes
Warm interglacial periods occur every 100,000 years in earth's climate. We are in one right now.
no
no
all periods
No.
no
yes around 11 days after
Periods occur each month not each day Periods last a minimum of 5 days and can range to 7 days.
Several periods of mass extinction