A group of psychologists believe that emotional insecurity may actually be a survival advantage. So now you can blame evolution for the fact that you've never had a relationship last longer than six months. Thanks, Charles Darwin!

Basically, there are two types of people in the world: Those with "secure attachment styles," also known as "suckers," who believe the world is a fundamentally safe place, and those with "insecure attachment styles," also known as "nutjobs," who know the truth: No one actually loves you, you don't deserve success, and the world is out to get you. Can you guess which one is better at staying in relationships? That's right, the ones who aren't positive that their significant others secretly hate them and think they're ugly.

But even if one type is better at being in a relationship, both types are apparently necessary for collective human survival:

Evolution would have favored a mix of these so-called attachment styles if mixed groups were more likely to survive than groups of only secure or only insecure individuals.

"Secure people have disadvantages," experimental psychologist Tsachi Ein-Dor of the New School of Psychology in Herzliya, Israel, told LiveScience. "They react slowly and then act slowly because they need to first get organized."

In the study, Ein-Dor and his colleagues placed subjects in mixed groups in a room together and then "simulated a fire" by starting a smoke machine. Those with "secure attachment styles," fundamentally trustful of the world, tried to befriend the smoke. Those with "insecure attachment styles" were convinced the smoke was cheating on them. (Actually, the "insecure attachment style" types just noticed the smoke more quickly, and were more likely to leave the room.)

To better illustrate the difference between attachment styles, let's see what the typical reaction to this study from each group would be:

Secure Attachment Style: "Hmm, how interesting! I'm glad all types of people are able to work together to better our collective chances of survival."

Insecure Attachment Style: "I knew I was right to be anxious about Karen."