the.com/reciprocity
The invisible debt every favor secretly installs in someone else's conscience.
hardwiredFree samples measurably boost sales through obligation, not taste
global glueEvery known human culture practices some form of gift-return
name originFrom Latin meaning back-and-forth, like a tide
dark sideBribes work by hijacking this exact instinct
animal versionVampire bats share blood with non-relatives who reciprocate