In 2010, researchers pooled 148 studies that followed more than 300,000 people for an average of 7.5 years. People with strong social relationships had 50% greater odds of surviving the study period than the most isolated. The link rivals well-known risk factors such as smoking and drinking, and it held regardless of age, sex or initial health status. It's an association, though: causation is hard to prove.
Remembering is not replaying a recording — it is rebuilding. Each time you recall a memory, it becomes temporarily malleable and can be altered before being stored again. That is why two people can sincerely remember the same event… differently.
In 2003, Johnson and Goldstein compared European countries. Where you must tick a box to become a donor, consent rates ranged from 4% to 28%. Where you're a donor by default unless you opt out, they topped 85%. People aren't more generous on one side; most simply stick with whatever option was chosen for them.