Correct answer: Papillary lines.
Comment: The project aims to compile biometric data for each of India's more than one billion residents. Due to hard labor, many farmers have effectively worn away the fingerprint patterns on their fingers.
Okay, let's try something easier...
In Jean-Jacques Annaud's film, priests in the 20th century devise a way to demonstrate the power of God to African tribes. The natives had never encountered X before, so some of them collapse. Later, the priest demonstrates a miracle, raising his hands to the sky for a moment to make it more convincing. Name X.