Bugs was designed with adult proportions

In character design ratio refers to the proportions of the body parts in relations to the rest of the body. Take Bugs Bunny for example. All of his limbs, including ears, are the same height and are in proportion to his head, giving him the look of an adult human. The proportions are based on;

The Golden Ratio – 1.618. This is a ratio that appears not only in design, but nature itself. It is the ratio between any two element. When the smaller section is compared to the larger section it should create a ratio of 1.618. And when those two elements compared to the next larger element you should get the same result. In Bug’s case – Hand x 1.618 = Face x 1.618 = Arms x 1.618 = body. Ergo the section of a person’s leg, the distance from waist to knee and knee to foot, should reach this ratio with the leg itself.

Edna From The Incredibles

Fibonacci Sequence – is another ratio with set mathematic but is a little easier to understand. If you measured up Edna, starting with her feet and worked your way up, you might notice that each section is equal to the sum of the lower two section. This is the Fibonacci Sequence, where every number is equal to the proceeding two numbers, (1, 1, 2, 3, 5, 8, 12, and so on). This sequence also naturally occurs throughout the universe and is very close to the golden ratio. If you divide the larger numbers in the sequence by the proceeding number you will get approximately 0.61. Some of the equations will come out at 0.618, but not enough to claim these as the same rule.

You may be thinking that Edna is a very strangely shaped woman so the Fibonacci Sequence can’t be good for character design. On a normally proportioned character the largest number of the sequence would be used for the distance from the top of the head to the waist. But when Edna was designed, the animators wanted to emphasis her face.

Why?

Face-ism Ratio – which is the ratio of face to body. In photographs where the face takes up most of the frame, (high face-ism ratio), the viewer focuses more on the personality and intellectual attributes of that person. If the photograph has a low face-ism ratio, (the face only take up a small part of the frame and more of the body is shown), then the viewer generally focuses on the physical aspects of the person in the picture.

They want you to want her.

Pixar wanted Edna to appear highly competent, intellectual and worldly. Which they achieved by making face stand out to the audience. Unlike this final character, whose name I don’t know, whose face is proportionally small. The animators have made her legs the main focus as long legs suggest full maturity. They have tried to make this character desirable by giving her long limbs and using the;

Waist to Hip Ratio – which has created a prefered ratio of 0.7 for women and 0.9 for men. This is because of estrogen and testosterone and their effect on fat distribution. High estrogen level result in a low waist to hip ratio, while high levels of testosterone result in a higher waist to hip ratio. We respond to this ratio because they are reasonably indicative of health and reproductive ability.

If you want to know more, the following sites have great information about the mathematics and biases of human proportions;