Y7bmW TIL that gum disease can be contagious. The bacteria that cause gum disease can pass from person to person. While you can't catch gum disease through brief casual contact, repeated and long-term contact through saliva (such as kissing) may increase your risk for periodontal disease.
BgYVb TIL that on the tape on which the beating of Rodney King was recorded, the footage is preceded by rubberneck recording of a film which was shooting nearby: Terminator 2, showing Schwarzenegger getting on a bike and riding away
rNbd0 TIL the Kaktovik numeral system is a base-20 Alaskan numbering system
NXJw8 TIL that Zambia’s Barbra Banda is the only footballer to score 3 hat-tricks at the Olympic Games — and was on the losing end each time
l7bMG TIL that US American trains are required to have bullet proof glass (specifically up to .22 calibre) on their locomotives
8eOxL TIL Napoleon's prowess in battle was so legendary, the Trachenberg Plan was drafted to specifically avoid facing Napoleon in battle while instead targeting his marshals and generals separately
P1DOJ TIL of Cistercian numerals, in which a single glyph can represent any integer from 1 to 9,999.
epbmE Today I learned the term carnal knowledge is an archaic euphemism for sexual intercourse.
VBblm TIL the glow in blue grottos is caused by sunlight that enters a cave through an opening being reflected on brightly colored seabed, with the water filtering out all wavelengths except for the blue ones.
X0bmP TIL there are glaciers in Africa
R5yV4 TIL that it is unknown how to properly pronounce "Halley's Comet"
wo4dP TIL that Rudolph the Red-Nosed Reindeer was first published in a booklet given out by the Montgomery Ward department store. They had been buying and giving away booklets for Christmas every year, and thought making their own book would save money.