Love is a mystery.

It is one of the most ancient of all the mysteries, and the most lasting. And one aspect of that mystery is how you can go so quickly from loving someone to absolutely, positively hating their living guts.

Now, neuroscience is explaining that part of the mystery.

A recent study out of the Wellcome Laboratory of Neurobiology took volunteers with a deep hatred for a specific individual and scanned their brains. It’s probably not a shock to learn that the majority of participants chose an ex-lover. Some selected a professional rival, and a small percentage chose a famous political figure.

Researchers then analyzed the neural activity of participants as they gazed upon photos of their Most Abhorred Person in the World (with reactions to people about whom they felt neutral as a control).

The results surprised even the scientists.

They found that the hate circuit includes two parts of the brain found in the sub-cortex: the putamen and the insula. The putamen is a part of the brain scientists already know has to do with contempt and disgust, and may also be involved in the motor system (the part of the brain that controls movement or action). The insula has been shown to be involved in responses to distressing stimuli.

The surprising part? According to neurobiologist and head researcher Professor Semir Zeki, “[T]he network involves regions of the putamen and the insula that are almost identical to the ones activated by passionate, romantic, love.”

In other words, the wiring in the brain associated with hate … is the same as that of love.

“Hate is often considered to be an evil passion that should, in a better world, be tamed, controlled and eradicated. Yet to the biologist, hate is a passion that is of equal interest to love,” Professor Zeki said.

Thus, while love and hate are at seemingly polar opposites in literature and in our common thinking on the subject, physiologically-speaking they are, quite literally, intimately related.

As it turns out, they’re not identical. But even the difference between them is cause for pause: When you scan the brain of someone looking at a person they hate, only a small part of the cerebral cortex (associated with reasoning and judgment) is deactivated; when they’re looking at someone they love, large parts of the cerebral cortex are deactivated.

In plain English, this means your ability to exercise logic and reason is switched pretty far off when you’re in love with someone, but if you hate them, you can exercise better judgment.

According to Professor Zeki, “This may seem surprising since hate can also be an all-consuming passion like love. But whereas in romantic love, the lover is often less critical and judgmental regarding the loved person, it is more likely that in the context of hate, the hater may want to exercise judgment in calculating moves to harm, injure or otherwise exact revenge.”

So: Not only does hell hath no fury like a woman scorned, but once she hates you, she’s thinking a whole lot more clearly.

The lesson here is not, of course, to feel free to hate people you used to love. It is simply to be kind and gentle with yourself if you do notice those kinds of feelings arising. Feeling murderous rage towards your ex doesn’t make you a bad person–if anything, this study demonstrates that there’s only so much you can do about that, given that it’s lighting up the same brain circuitry for you.

The question isn’t whether you feel the hate, it’s what you do with it.

There are lots of ways to stuff down distressing feelings: eating Oreos, watching Netflix, over-exercising, playing video games, even working. It’s harder and less comfortable to sit down and actually feel the feelings. Yet that’s what many psychologists (not to mention mystics) will tell you actually helps you move through and past them, so you can let go and move on.

Love. Hate. Love. Hate.

If they’re that linked in the brain, then it doesn’t just work one way around. If you can go quickly from love to hate, then you can also go from hate to love. And not only love of another. There’s also self-love. Love of nature. Love of humanity.

Just love.

Forgiveness can be a long path, but it’s a worthy one. And forgiveness of others is far easier to attain once you have forgiven yourself.

Maybe, to get there, all you need is love.

Originally published at www.inc.com