I'm in two minds about pinning this. It's a useful tutorial for fashion illustration. However, the illustrations border on promoting anorexia. It would be good if fashion illustration started showing normal rather than elongated and emaciated forms.
Math in nature: The famous Fibonacci sequence, a series of numbers in which each is the sum of the preceding two .), shows up everywhere in nature—in nautilus shells, in pine cones, and now in the structure of cacti.