You are having a completely normal day. Walking somewhere you have walked a hundred times before, checking your phone, thinking about nothing in particular. And then you see them — and everything after that happens without your permission.
Your face changes before you know it has. Your heart does not just beat faster; it slams, from around seventy beats a minute to over a hundred, in about one second. That is not a feeling. That is a measurement. Your palms start sweating. Your mouth goes dry. Your stomach turns over.
And you still have not said a single word.
Deep inside your brain sits a small almond-shaped structure called the amygdala. Its job is simple: spot anything important and hit the panic button immediately, before the slower thinking parts of your brain have finished working out what is going on.
Here is the part nobody tells you. Your brain runs the same alarm for your crush that it runs for a tiger walking into the room. Same wire. Same siren. Your body cannot tell the difference between danger and wanting.
The alarm squeezes your adrenal glands, which sit just above your kidneys, and they dump adrenaline into your blood. That is the heart-slam. That is the sweat. Your body is preparing to fight or run away from a person you wanted to say hello to.
Which explains why you did neither, and stood there like a statue instead.
It also explains the stammer. Under that adrenaline surge, blood is redirected toward large muscles and away from the parts of you that were about to form a sentence. So “hi” came out as “h-hey. hello. hi.” Your tongue was never the problem. Your blood supply was.
Dopamine goes first, and it is badly misunderstood. Dopamine is not the happiness chemical. It is the wanting chemical — the one that drives pursuit rather than enjoyment. It is the same system a slot machine exploits. Every glance from them is a jackpot pull, and your brain keeps pulling the lever.
That is why one look can carry you through an entire day. It is why you re-read their one-word reply at two in the morning, fourteen times, zooming in on the word seen and studying the timestamp like evidence. Your brain is not in love yet. It is gambling.
Norepinephrine comes next: pure focus fuel. It puts your whole body on alert. Colours get sharper, time seems to slow, the room comes into detail. You will remember what they were wearing today for the next six years. You cannot remember what you ate for lunch yesterday.
Cortisol drips in underneath the whole thing. That knot in your stomach that everyone calls butterflies? Butterflies is a nicer word for it. It is stress — measurable, chemical stress.
And then something stranger. Researchers measuring people in the early stages of romantic love found their serotonin, the calm chemical, had dropped — to levels normally seen in obsessive-compulsive disorder. Not as a metaphor. The same reading, on the same test.
Which is why you lie awake replaying a four-second conversation, and why estimates suggest people in this state spend as much as eighty-five percent of their waking hours thinking about one person. Your brain has hijacked its own search engine and pointed it at a single face.
While this runs inside, the outside is giving you away.
Adrenaline widens the blood vessels in your cheeks, and you blush. You cannot stop it — blushing is involuntary, and Charles Darwin called it the most human of all expressions, because no other animal does it.
Your pupils widen too. In ordinary light they would stay small; looking at someone you are drawn to, they physically open to take in more of them. Other people find dilated pupils attractive without ever knowing why they do.
And without noticing, you fix your hair in a shop window. You straighten your shirt. Psychologists call it preening. Your body signed you up for a performance you never agreed to, in front of an audience of one.
Out of everyone you have ever walked past — why them?
Your brain built a template years ago and filed it somewhere you cannot reach. Faces you trusted as a child. A voice that sounded like safety. Someone who was kind to you once, at an age when kindness mattered more than you could have said. Some psychologists call this a lovemap.
When somebody matches enough of that hidden template, the alarm fires. You never chose the template. You just run it, the way you run your own heartbeat, without ever being asked.
So why does your body do all of this over one person walking past?
Because the system is old. For your ancestors, finding a partner was not romance; it was survival. The genes that made hearts slam and palms sweat got passed on. The calm, casual ones did not — they did not try hard enough to leave anyone behind.
Which means every single person in your family line, all the way back, felt some version of this. And that embarrassing moment when you spilled your coffee is not you malfunctioning. It only feels like a malfunction. It is two-hundred-thousand-year-old software running exactly as designed. You are not glitching. You are working.
One more thing nobody mentions: the cocktail has an expiry date. The research suggests the chemical chaos runs one to two years at most — your body cannot keep an alarm ringing forever. What replaces it is attachment. Different chemicals, quieter, and a much longer warranty.
Short detours through the parts of being human that nobody explains.
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