* To Startle the Threat: When we make terrifying faces, we try to startle and scare away the threat. This can be an effective deterrent against predators and other dangers.

* To Communicate Fear: Our facial expressions communicate our emotions to others. When we make terrifying faces, we signal to others that we are in danger or afraid, which can prompt them to help.

* To Relieve Tension: Screaming and making terrifying faces can help to relieve tension and release pent-up emotions, which can be physically and mentally beneficial.

* To Express Pain: Screaming and making terrifying faces can also be a way to express severe physical or emotional pain.

Additional Insights:

* Babies start to make terrifying faces around 7-8 months of age when they develop self-awareness and the ability to understand emotions.

* Research suggests that certain brain areas, such as the amygdala, hypothalamus, and prefrontal cortex, are involved in the production of terrified faces.

* Screaming and making terrifying faces can be part of a 'fight or flight' response, an automatic reaction to life-threatening situations.