Hello future psychology buffs! Let's dive into the riveting world of reciprocal altruism. Picture this, you are at a pool party and someone you've never met before falls into the water, gasping for air. You are a good swimmer, so you dive in to save them. Now, this act may look like an act of heroism but guess what? It also has an evolutionary advantage! 😮

This big term 'reciprocal altruism' was coined by the amazing Robert Trivers in 1971. In simple terms, this means you do something nice for someone (even a stranger) and they'll likely do something nice for you in return. Kind of like, "scratch my back, I'll scratch yours". Or in our example, "save me from drowning today, I might save you from a runaway trolley tomorrow." It's not always about self-sacrifice; it's also about ensuring your own survival, because help comes when you need it most. 🤔

There's a catch, though. Some sneaky people might take advantage of your good nature, accepting your help but never returning the favor. Trivers calls these folks 'cheaters.' If they're caught, they might get excluded from the group, meaning no more help for them. It's like the kid in class who always asks to borrow your notes but never shares his chocolates. 🍫