Fear of loss of romantic partner and indignation at having been treated unfairly
Most people have experienced jealousy at some point in their life. We usually know how to identify the emotion when it appears in ourselves, and we are fairly good at telling when others experience jealousy on the basis of their actions. But what exactly is jealousy?
On a traditional model in evolutionary psychology, jealousy is an inherited response that once increased our chances of survival. Men, it has been argued, exhibit jealousy primarily in response to sexual threats to the relationships they are in. The reason for this supposedly is that only those of our male ancestors who were the actual father of the children they provided for were guaranteed to have their DNA passed on. Women, on the other hand, exhibit jealousy primarily in response to emotional threats to the relationships they are in. The reason for this allegedly is that only those of our female ancestors who had someone to provide the food for their children had children that would survive, increasing the chance that their DNA would get passed on. This eventually gave rise to men with a sex-jealousy gene and women with an emotional-jealousy gene.
There are many problems with this account of jealousy. One is that it jealousy isn’t equally pronounced in all cultures, which suggests that even if it does have a genetic root, it also has a strong social component. In other words, jealousy is partly cultivated.
As I have argued elsewhere, the evolutionary root of jealousy may not be sexual or emotional competition but the endowment effect. The endowment effect is our inherited tendency to assign greater economic value to something already in our possession than to something that we don’t own. The endowment effect by itself does not fully explain jealousy. The further factor, which is cultural, is the tendency to consider our partners our sexual and emotional property, providing us with exclusive rights to sex and intimacy with them.