Is there really a thin line between love and hate? Scientists explore the age old question

The line between love and hate is often described as painfully thin. This is a peculiar concept given the two polar opposite definitions of the words one can find in any dictionary. It seems logical to me that the similarity may arise from the fact that love and hate are so often felt for the same person at different times, rather than an inherent similarity between these emotions.

For example, being excruciatingly close to losing love in a romantic relationship can so easily teeter on the edge of loathing. Tempestuous relationships between siblings often flicker between jubilant affection and animosity, when the line between joking about a delicate subject and exposing a deeply sensitive area becomes a little too blurred. When our dearest friends are openly disapproving of our clearly masochistic behaviours that we won’t accept are unhealthy for us, even if we inwardly know they are correct, it is common for appreciation of their sentiments to lead to resentment. In essence, it seems to me that you can only truly hate someone if you once loved them.

Although science does not yet hold the answer to many questions regarding human emotion, there has been evidence that I am incorrect, and that the two emotions are in fact, intrinsically linked. Professor Semir Zeki, co-author of a study entitled ‘Neural Correlates of Hate’ states that ‘to the biologist, hate is a passion that is of equal interest to love’. In this study, Zeki and John Paul Romaya, scientists at University College London, used a functional MRI scanner in 17 normal human subjects as they viewed the face of a person they claimed to feel intense hatred towards. These were all past lovers or work rivals, excluding one famous politician. They also viewed faces of acquaintances for whom they had neutral emotions.

‘To the biologist, hate is a passion that is of equal interest to love’

The study found a unique pattern of brain activity in the context of hate that was stimulated when people saw the faces of their enemies, termed the ‘hate circuit’. However, this pattern shared two areas of activity that correlated with love, that were stimulated when participants viewed the face of a romantic or maternal lover in a previous study. These structures were the putamen (a round structure located at the base of the forebrain) and the insula (part of the cerebral cortex folded deep within each hemisphere).

This link may be the neurological reason why love and hate seem to overlap so much in life. It punctuates that although they are seemingly opposite, both emotions can lead to the same behaviours. Both love and hate have led individuals to commit bold, heroic, courageous and evil actions. Intriguingly, the scientists found the level of activity in the ‘hate circuit’ correlated with the intensity of hatred the participants declared. In other words, hatred could be objectively quantified. This may have implications in the legal system concerning malevolent crimes, as an fMRI scanner could potentially be used to elucidate the depth of hate a perpetrator felt for a victim. However, considering the hate and love circuits overlap, are all crimes where heightened emotions are involved simply ‘crimes of passion’?

Earlier research has implicated the putamen as both the part of the motor system that translates thoughts into actions, and in the perception of disgust and resentment. This seems logical, as the putamen could be involved in preparing an aggressive response in the context of love, for example in warding off a romantic rival. The insula has previously been shown to be involved in the brain’s response to emotionally distressing stimuli. This also makes sense, as feelings of distress can be elicited by seeing both individuals we hate, as their presence may sadden or exasperate us, and those we love, for example if we no longer hold their affection.

The most striking and perhaps surprising part of Zeki and Romaya’s research to me however, is not that hate and love are tangled together. It is that the main difference in the two brain patterns activated was that areas of the frontal, temporal and parietal cerebral cortices – linked to judgement and reasoning – deactivate in love compared to hate.

This is surprising to me, given that both hate and love seem to be all-consuming passions. Nevertheless, it implies that people in love make less rational decisions, and are less judgemental of their partners, whereas focus and logic are maintained in behaviour towards an enemy. ‘It is more likely that in the context of hate the hater may want to exercise judgment in calculating moves to (cause) harm’, Zeki suggested in a statement. Could this possibly mean that if someone is a more rationally inclined and pragmatic individual they are more innately driven to feel hatred? On the other hand, if someone is generally less logical in their approach to life, do they fall in love more easily? These questions remain unanswered.

Another aspect of hate this research does not seem to explain is how hatred can be directed towards entire groups of people, whilst love is often steered toward specific individuals in our lives. We rarely claim to love all people of a particular social group or ethnicity, whereas groups defined by their race, gender, social, political or cultural background are often detested as a collective. Perhaps Zeki will address these various aspects of hate in future research.

Overall, this research shows we are less critical and less rationally inclined when it comes to those we may be infatuated by, lust after, or platonically cherish. This could all be taken to mean we really do let our hearts rule our heads. We really are fools in love.