Rejections are the most common psychological injury we encounter in daily life. They range in 'potency' from mild such as when friends fail to share our Facebook posts, to truly devastating, such as being blindsided by divorce or being shunned by our families. The one thing all rejections have in common is -- they hurt! Indeed, the expression 'hurt feelings' is one we tend to associate almost exclusively with rejection, as do cultures around the world.

So, what exactly happens in our brains that makes rejections so painful?

To answer that question, scientists placed people in fMRI scans (functional MRIs show what happens in the brain when someone performs a specific task), and had them play a computerized ball-tossing game with two other people. The game was rigged such that subjects always got excluded (i.e. rejected) by the two other players after a couple of rounds of tosses.

We know from previous fMRI studies that physical pain typically activates two types of regions in the brain; one associated with the 'distress' of physical pain -- an affective (emotional) component, and the other with the physical sensation of pain -- a somatic (sensory) component. Getting rejected in the computerized ball-tossing game caused activation of the same network of brain regions that supported the affective (emotional) component of physical pain but not those that supported the physical-sensation (sensory) component.

Of course, getting rejected by two unseen strangers in a computerized game is pretty mild as far as rejections go. What happens in our brains when the rejection we experience is really meaningful?

To that end, people who recently experienced an unwanted and painful breakup were placed in the fMRI scanners while looking at photographs of their ex-partners and thinking about the intense rejection they experienced (in case you were wondering, yes, they were well compensated). Sure enough, this time even the regions of the brain that supported the sensory (physical sensation) component of physical pain became activated.

In other words, the same pathways in the brain get activated when we experience meaningful rejections as get activated when we experience physical pain -- hurt feelings actually hurt.

The question is why did our brains evolve a response to rejection that mimics physical pain so closely?

The answer lies in our hunter gatherer past. When we lived in small nomadic groups, being ostracized from our tribes was akin to a death sentence, as no one survived very long alone. Therefore, our brains developed an early warning system (rejection) to alert us when we were at risk for being kicked out of our tribe. Those who experienced rejection as more painful were also more likely to correct their behavior, avoid getting kicked out of the tribe, and therefore more likely to survive and pass along their genes.

Rejection is unique in this way. The emotional distress caused by other common psychological injuries such as failure or guilt pales in comparison with the sheer emotional pain associated with most rejections. Keep that in mind the next time you experience a rejection. The pain you feel does not mean you are needy or weak -- it just means you're wired that way.