The ‘green-eyed monster’ brings on strong feelings that can include fear, insecurity and anger, and in extreme cases lead to violence.
Scientists have now pinpointed jealousy in the monogamous mind giving them new insight into the emotion that keeps couples together – and also tears them apart.
They found two key areas of the brain are stimulated by jealous feelings – the cingulate cortex and lateral septum – which are geared toward maintaining a bond in the face of external challenge.
The team found feeling jealous could actually be an evolutionary advantage, and we may have inherited it from our ancestors because it helps us protect resources such as our homes and children.
Scientists have pinpointed jealousy in the monogamous mind giving them new insight into the emotion that keeps couples together – and also tears them apart (stock image)
Little is known about the biology of jealousy and its role in the evolution of long-term pair bonding.
Although it can be an unpleasant emotions it can also play a positive role in social bonding by signalling a relationship may need attention and can be important for keeping a couple together.
‘Feeling jealous could be an advantage evolutionarily because our adult romantic relationships often involve resources that could be threatened by an outsider’, Dr. Karen Bales from the University of California told MailOnline.
Researchers studied coppery titi monkeys, a monogamous primate where adults form a strong pair bond.
‘For a titi monkey, these resources include a shared territory, joint care of infants, etc. (not that different from the resources in a human relationship, actually)’.
The neurobiology of pair bonding is critical for understanding how monogamy evolved and how it is maintained as a social system.
‘Jealousy is especially interesting given its role in romantic relationships – and also in domestic violence’, said Dr Bales , who authored the paper with Dr Nicole Maninger.
Titi monkeys form an attachment with their partner, show mate-guarding behaviour and become distressed when separated – similar to a romantic relationship in people.
The researchers induced a ‘jealousy condition’ in male monkeys by placing them in view of their female partner with a stranger male.
Scientists studied bonded titi monkeys which show mate-guarding behaviour and become distressed when separated – similar to a romantic relationship in people (stock image)
After 30 minutes of viewing – during which the behaviour of the males was filmed – brain scans were performed to see which areas were activated by each condition.
Researchers also measured the levels of various hormones thought to be involved in pair bond formation, mating-related aggression, and social challenge.
There are two areas of the brain that are activated by feelings of jealously.
The first is the cingulate cortex which is an area of the brain that is often activated by social pain – for example, being excluded from a social activity.
‘Jealousy is an emotional reaction to a form of social rejection where our relationship is being threatened by an outsider (and as adults, our pair bonds are often the strongest relationships we have)’, Dr Bales said.
‘Feeling jealous could be an advantage evolutionarily because our adult romantic relationships often involve resources that could be threatened by an outsider’, she said.
‘So, it makes sense that the cingulate would also be involved in jealousy’.
The second part of the brain that is activated is the lateral septum, a brain area that across many species, is involved in social recognition as well as in some types of aggression.
‘In our studies of titi monkeys, we have seen that it is involved in other aspects of pair bonding including the formation of the pair bond and reactions to short separations from the pair-mate’, said Dr Bales.
‘Jealousy is an emotion that is geared towards preserving the pair bond, so it makes sense that the lateral septum is also involved here’.
The jealous males showed hormonal changes as well, with elevated levels of testosterone and cortisol.
Those who spent the longest time looking at their pair mate next to a stranger male showed the highest level of cortisol, an indicator of social stress.
The rise in testosterone was expected due to its association with mating-related aggression and competition.
The question remains as to whether jealousy is the same in female titi monkeys as in males.
‘A limitation of our study is that we only looked at males,’ said Dr Bales.
‘Sex differences in the neurobiology of social behavior may ultimately explain questions like why more boys than girls have autism, and why men and women act differently in romantic relationships.’