Jealousy is seen as a negative force. It's the main fuel for crimes of passion and is linked with brutality, including domestic violence, and even murder. But the great psychologist Sigmund Freud believed that it's not only normal, it's actually desirable to feel jealous. And like all other emotions it's developed to give us the best guess at what's happening in our lives.
The thinking is that the emotions systems developed to give us instant solutions to commonly experienced problems in our environment. That meant that very quickly the whole body could respond. So it's not just a thought thing but that literally the emotions play an important role in coordinating the internal functions; heart rate, respiration, muscle tension and the like. So these developed really to give us very instant kinds of solutions to commonly experienced – either threats or opportunities – in our environment; things that related to surviving in comfortable ways.
People are at their healthiest and at their happiest when they're involved in satisfying relationships; whether we're talking about childhood or we're talking about adulthood. Engaging in satisfying relationships is associated with all kinds of wonderful things; lower cardiovascular threat, greater immune system response, greater wellbeing. And so what jealousy does is it alerts you and impels you to the threat that your relationship is going to be lost. I like to call jealousy a social emotion as opposed to kind of a more basic emotion. And most of us accept the view that we have basic emotions like anger and fear that impel us to flee a danger or to attack a conflict. Social emotions are emotions that you're going to see in social species like humans, and what they do is help us navigate our social landscape, much as more basic emotions help us navigate the physical one.
The main point about jealousy is it's not just about, is my partner having sex with someone, or is my partner saying 'I love you' to someone – because that only happens in terms of romantic relationships at a certain stage of one's life. It's really about protecting valued relationships at all stages of life, because you have to be successful as a child in protecting relationships to reach sexual maturity. And then you have to be able to form relationships with romantic partners as well as with other individuals to help you succeed in life, and it's the grand total of that that I think makes you lead a very adaptive life, both in terms of propagating your genetic material, but also in terms of having a life well lived.
All humans at kind of a very innate level have the capacity to feel jealous, and will feel it when they sense that the relationship is being threatened, but that's the integral part. What determines when you feel that your relationship is being threatened, that varies a lot by cultural, by social learning, by past experiences. So think about your friends, you co-workers. Some individuals may react incredibly jealously when their partner simply smiles at someone else, and other people that doesn't bother them at all. And I think that is related to how the actions by their partner make them feel about themselves. Some people who have different secure levels of attachment may be more or less jealous by a certain act. And some cultures allow certain interactions between men and women that other cultures proscribe, and I think as we grow through our lives we're constantly tuning our threat detection mechanisms, so to speak, based on our past experiences and based on our culture.