A commonly used put-down is “stop being so emotional”, and it often carries sexist undertones. But what’s wrong with being emotional? And, anyway, the command above is usually wrapped up in an emotion itself, such as anger or cold indifference.

Science is making new discoveries about the nature of emotions. For example, it is linking human feelings to specific areas of the brain that "light up" when scanned. But "the answer to the question 'What is an emotion?' lies not only in our biology or private psychological histories," says Dr Tiffany Watt Smith, author of The Book of Human Emotions: An Encyclopedia of Feeling, from Anger to Wanderlust. "The way we feel is also enmeshed in the expectations and ideas of the cultures in which we live."

Watt Smith has been carefully documenting emotions from around the world at a research centre at Queen Mary University of London. “There are 154 emotions in the book, but there might have been many more,” she says, providing today’s idea: “Approaching emotions as first and foremost biological facts misrepresents what an emotion actually is.”

René Descartes thought there were only six core emotions, and if the movie Inside Out can be believed, there are only five. You’ve identified more than 150. How so? 

“The idea that our messy, complicated emotional lives are constructed out of just a handful of fundamental feelings has been around for over 2,000 years. Today, evolutionary psychologists argue that a few emotions evolved specifically to protect us from harm – like disgust – or help forge communities – like happiness – and that therefore these building block or ‘basic’ emotions are the same for all people around the globe.

"The problem with this kind of approach is that it ignores the role that our culture plays in shaping our emotional responses. Fear might seem like an irreducible emotion of our most animal selves. But the Pintupi, whose home is in the deserts of western Australia, speak of as many of as 15 distinct sorts of fear, for instance the fright that makes you jump up and look around you (nginyiwarrarringu); the creeping dread that a rival is seeking revenge (ngulu); and the terror felt when malevolent spirits are around (kanarunvtju). Is one of these more 'basic' than another?"

If you were to add just one more emotion to the Inside Out line-up – joy, sadness, fear, anger and disgust – to better represent the human condition, what would it be? 

“What about an emotion like nostalgia? It’s a kind of sadness, of course, but also wistfulness, a longing for something lost. And it can be pleasurable too. I often try to savour the moments I feel nostalgic, in the same way I do when I feel joy or pleasure. Actually, in the 17th century, nostalgic longing was thought very dangerous too; it was sometimes so powerful it could kill you (the last person thought to have died of nostalgia succumbed in 1914). So it’s not easy to put emotions into boxes.

“Anyway, to your question, I’d add an obscure emotion to the list. Maybe it doesn’t sum up the human condition as such, but it’s fun to think what would happen if it did: basorexia, a sudden urge to kiss someone.”

Who discovers emotions: neuroscientists or poets?

"Poets. The neuroscientist Giovanni Frazzetto has written poignantly about the limits of physiological knowledge when it comes to understanding emotions. He could show you a brain or point to an fMRI scan, and many of us, myself included, would feel a sense of wonder and astonishment at how much science can tell us about ourselves. But this knowledge can seem rather remote when we're, say, in the midst of a white-hot rage, or experiencing the strangely 'formal feeling' of grief that Emily Dickinson wrote about.

“Understanding the brain can tell us a lot, but not much about what our emotions mean to us and why they feel as they do. It’s in this sense that poets ‘discover’ emotions. They find a vocabulary for them. They make emotions vivid, real and relatable, and we use their words to help us understand our emotions and where they come from – and that helps us feel less alone.”

What’s the newest emotion you’ve come across?

“I’m quietly thrilled when hard-to-pin-down feelings earn new titles. Like Fomo (fear of missing out), something I suffer from constantly. Discovering this word was quite a relief, it meant that other people were struggling with an overload of opportunities too. When we bother to name an emotion, it can tell us a lot about our shared preoccupations.”

In philosophy and science, reason and emotion are traditionally presented as opposites. Are the best academics not very emotional?

“In the last two decades a great deal of research has been dedicated to breaking down this perceived opposition. Emotions have been shown to play important roles in apparently cold moments of rational decision-making.

“And as for academics, well, as in any profession, we have our share of psychopaths. But the rest of us are very emotional. There are the excitements and frustrations of new research, the thrill of making discoveries, the pleasure of seeing a student succeed, rivalries with colleagues, terror as deadlines loom. Without all of this, it’s hard to imagine how anyone would motivate themselves.”

MODERN EMOTIONS

• Ringxiety: Mistakenly sensing that your mobile phone is going off.
• Torschlusspanik: The agitated, fretful feeling we get when we notice time is running out (from the German: "gate-closing panic").
• Cyberchondria: Anxiety about "symptoms" of an "illness" fuelled by internet "research".
• Malu: Being flustered in the presence of someone of higher status (from Indonesia).
• Pronoia: A strange, creeping feeling that everyone's out to help you.

From The Book of Human Emotions