When’s the last time you got shivers up your spine? It turns out there’s a scientific reason for this bizarre but universal human sensation.
Spine shivers and goosebumps can be caused by both “good” and “bad” sensations — a scary movie or a sweet kiss. But either way, the phenomenon is caused by the same physiological response.
Your body responds to emotion or stress just like our animal ancestors did. The movement of the arrector pili muscles causes the skin to contract, and that raises your hair. The same thing happened when our animal ancestors felt threatened because their natural response was to try to look bigger than their attackers. The hair fluffed out to achieve that effect.
The same response occurred when our ancestors felt cold – the hairs on their bodies would stand up to provide extra insulation.
In humans, this physiological response results in goosebumps, body hairs sticking straight up, and, yep, shivers down your spine.
Of course, nowadays, we no longer experience this sensation solely when we’re cold or being threatened by a predator. We also experience it whenever something scary, delightful, or otherwise emotionally overwhelming happens suddenly.
The shivers-down-the-spine reaction is controlled by a part of the brain called the hypothalamus. The hypothalamus is also connected to our emotions, so it can trigger a similar physical response whenever we feel any strong emotion, like love or fear. Our bodies are suddenly rushed with adrenaline, which causes goosebumps, sweaty palms, tears, increased blood pressure, or shivers.
So, the next time you watch a scary movie or have an emotional moment and you suddenly shiver, you know exactly why!