Life modeling is holding poses (usually between 1-30 minutes) in the presence of artists while completely or partially nude.
Rendering an image of the human form is one of the oldest known arts in the world. Ancient cave drawings would invariably contain drawings of humans. Great artistic masters would spend time studying and rendering the human form… they considered the practice essential to their craft. Every art program in modern academia requires its students to learn figure drawing, the skills are so basic and important.
Models sometimes pose with clothes on. These poses are called “draped.” But most often, the model is completely nude. This affords the artist the ability to see the muscular structure spread upon the skeletal structure. One can paint a landscape and get proportions wrong, but the human form must be rendered correctly.
In this one specific arena, the normal societal structures against open nudity are suspended. The model disrobes, strikes a pose, and then holds perfectly still… whilst artists look upon him/her with great focus, and attempt to render a likeness.
I have a coin that I carry called a tetra drachum. It’s an ancient coin from the reign of Alexander the Great, struck more than 300 years BC. On one side is a portrait of Hercules wearing a lion skin cap, and on the obverse side is a full figure of Zeus with a staff and eagle. Even here, over 2300 years ago, there were artists who sculpted from the figure.
To pose for artists in the nude is an old craft and an honorable one.