What Emotions Do Lines Communicate?

In nature, seashells contain tons of lines.

Lines communicate emotion through the different shapes sizes shades and hues they come in. Soft, curved lines used in the drawing of a face may suggest a friendly face that communicates nice or positive emotions. In contrast, straight thick lines, may suggest a more negative or serious emotion.

The top left is a structural drawing, underneath it is an outline drawing,
underneath that is a contour drawing and the top right is a gestural drawing