Why is the number-one rule of small talk is to get the other person talking about himself or herself? Because humans adore gabbing about themselves, so much so that 30 to 40 percent of our speech is limited to describing our own experiences and opinions. Not surprisingly, we're even more self-disclosing on social media, with around 80 percent of tweets, status updates and selfies (obviously) sharing what we had for lunch and other scintillating and showoff-y personal details.
To better understand why humans spend so much time fluffing our own feathers, so to speak, a team of Harvard psychologists looked a fMRI brain images of participants while talking about themselves. It turns out, our brains like us talking about ourselves as much as we do. During self-disclose, the mesolimbic dopamine system, often nicknamed our neurological "reward" center, shows increased activation, similar to what happens when we eat tasty food, receive money, or spot an attractive lady or gent strolling down the sidewalk. Further confirming how much we innately enjoy humble-bragging and whatnot, the Harvard study participants also were likelier to opt to talk about themselves than accept a cash reward, as I explain in more detail in this SMNTY video:
In the study discussion, the psychologists explain:
"In an ultimate sense, the tendency to broadcast one's thoughts and beliefs may confer an adaptive advantage in individuals in a number of ways: by engendering social bonds and social alliances between people; by eliciting feedback from others to attain self-knowledge; by taking advantage of performance advantages that result from sharing one's sensory experience; or by obviating the need to discover firsthand what other already know, this expanding the amount of know-how any single person can acquire in a lifetime. As such, the proximate motivation to disclose our internal thoughts and knowledge to others around us may serve to sustain the behaviors that underlie the extreme sociality of our species."
In other (and less academic) words, we show off in order to survive.