The human form has been the subject of art for thousands of years. Drawings inside cave walls depicting man and woman as stick type figures were early examples of such art. No matter how bizarre the interpretation of the male and female form appears, it's almost always identifiable. They could be drawn round, thin, short, tall, standing up or laying down, with or without faces, with or without limbs and they're still almost always distinguishable as the human body.
Art classes featuring nude models teach students how the body's connected, so that they can begin to sketch and paint it accurately. Students volunteer to pose nude in college art classes all over the country, where they sit motionless for extended periods of time while students attempt to simulate the angles and shadows created by the model's limbs. Models of all different sizes, male and female, are available and provide an opportunity for students to observe and practice a variety of lines, shapes, shadows and contours. Some classes may be sketching, some may be drawing, some may be painting, where they would learn how to mix the flesh colored paint for their subjects.
Now we've gone from the cave wall, to the canvas, to the camera. The human form is one of the most photographed subjects in advertising. It's photographed fully clothed, partially clothed and fully nude. There are pictures of models in magazines, on billboards, on posters, on book covers, on CD cases and a myriad of other items. The fully and partially nude images can be found in adult magazines, calendars, and adult movie publications.