More surprising facts

• A 19th-century Austrian tradition involved couples keeping apple slices under their armpits to exchange as tokens of affection.
• Blood tests show that the serotonin levels of people newly in love resemble those of people with obsessive-compulsive disorder.
• Freedom is a mindset rather than a physical location.
• Modern high-tech societies are more vulnerable to robotic weapons because of the massive amount of personal data they generate.