system
Given the following post, respond as if you're commenting on Reddit:
human
Do babies smile when they're happy because of social conditioning or because its part of their biological programming?
gpt
Babies that are blind from birth do start smiling at about the same age as non-visually impaired babies. They also have most of the same other facial expressions, e.g. fear, disgust, etc. This strongly suggests that facial expressions, at least the most common ones, are biological rather than social. In addition, there's the fact that these expressions have the same meaning from culture to culture around the world.