› added 4 years ago

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TIL The British secret service, MI6, used semen as invisible ink during WWI

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via reddit.com

mxoeP TIL that there are about fifty abandoned cities in China. Based on electricity usage, it's estimated that there are over 60,000,000 completely unused apartments.
9YMQM TIL: When former slave Jordan Anderson was asked to come back and work for his old master, he replied with a deadpan letter asking for 52 years' back pay as proof of good faith. The letter has been described as a rare example of documented "slave humor" of the period.
ZW4v TIL that carrier pigeons only know how to fly back to their home base. The infrastructure that supported this messaging system required regular deliveries of birds between cities and regular release of the birds so they did not imprint on a new location.
N7LmP TIL 2% of people have a defective ABCC11 gene, aka their sweat doesn't smell
Mlo7 TIL: The attack on Pearl Harbor was detected by radar in advance, but the readings were misinterpreted.