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In the 1990’s the philosopher Haddaway posed a critical question: What is love? This Valentine’s Day, many of us will experience love and companionship. We like to think of love as an amorphous, idealistic quality, but there are serious biological underpinnings. What is the biology behind love, and is the heart really where love lies (spoiler: maybe?)

We know that the brain directs our physical actions, but for the brain to come up with an idea, it needs input from the outside world. Interestingly, the brain can’t sense anything directly. If someone were to open up your skull and have a poke around, you would undoubtedly have a weird bit of sensation, but you wouldn’t experience the feeling of touch on the brain. We need special sensors (usually located on the skin) to feel things like touch. Indeed, our brain relies on signals coming in from all over the body to tell us about the outside world. Interestingly, we also rely on signals to tell us about the inside world – what we are experiencing. The brain interprets signals from the body, and we can experience that interpretation as an emotion.

As an example: your heart beats automatically all day, every day, at a hopefully regular interval of around once a second. When you see a scary event, such as a wild lion charging you, your brain and body respond in sync. The heart rhythm changes, beating much faster to provide your muscles, sensory organs, brain, etc., extra oxygen in order to move fast. But this effect isn’t strictly rational. After we escape from the lion, we still feel “amped up.” This effect can last for thirty minutes or so, and the reason for the long-lasting effect is complicated. Our autonomic nervous system – the one in charge of things we don’t consciously control – has kicked into action. This pathway acts like cupid, shooting cortisol through our body and activating special nervous system pathways that take a while to cool down. But our brain also looks at the state of our body to interpret our emotional state. If our palms are sweaty, we’re breathing heavily, and our heart is racing, the brain interprets that as being amped up and decides we’re still pretty excited or scared. The brain is in charge of deciphering which emotion we’re feeling, but the body lets us know how strongly we’re feeling that emotion.

This is why we sometimes still feel the need to continue an argument after the other party has conceded. It’s why telling someone to “calm down” doesn’t work – but taking some deep breaths does. Meditation, stretching, exercise, and sleep all affect our emotional state because the brain looks at the condition of the body and tries to figure out how it’s feeling. In addition, a healthy heart that can respond well to changes may increase a person’s emotional regulation. Does it do this with love as well?

According to neuroendocrinology researcher Robert Sapolsky, it does! The science may not be entirely clear, but the easiest way to be certain of this is by looking at the irrationality of love. Love doesn’t make sense, and it’s so strong that we base enormous portions of our life just on this single emotion. Love is the basis of countless pieces of art, works of literature, grand buildings, and justifications for war. When we experience love – that fluttering of the heart, the excitement and elation, the involuntary smile on our face, and the giddiness so high that our mouths stop working and we say embarrassing, cheesy things – it’s the body to blame. Our heart races when we’re in love and the brain sees this as a huge exciting event – because it is. Just seeing the person we love can change our heart rate. Physical touch from a loving partner can help lower our heart rate in response to stressful situations. And the long-term effects of companionship sometimes include a partial synchronization of our heart rhythms.

We can thank our hearts for at least some of what we call love. This Valentine’s day, get your heart racing with a partner or loved one, and keep that heart beating strong!

By Benton Lowey-Ball, BS Behavioral Neuroscience

Ditzen, B., Neumann, I. D., Bodenmann, G., von Dawans, B., Turner, R. A., Ehlert, U., & Heinrichs, M. (2007). Effects of different kinds of couple interaction on cortisol and heart rate responses to stress in women. Psychoneuroendocrinology, 32(5), 565-574. https://doi.org/10.1016/j.psyneuen.2007.03.011

Kandel, E. R., Schwartz, J. H., Jessell, T. M., Siegelbaum, S., Hudspeth, A. J., & Mack, S. (Eds.). (2000). Principles of neural science (Vol. 4, p. 980). New York: McGraw-hill.

Mather, M., & Thayer, J. F. (2018). How heart rate variability affects emotion regulation brain networks. Current opinion in behavioral sciences, 19, 98-104.

Sapolsky, RM. (various works)