Why Zebras Don't Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping

by Robert M. Sapolsky

Apples have waists that are bigger than hips, producing a “waist-hip ratio” (WHR) that is bigger than 1.0, while pears have hips that are bigger than waists, producing a WHR that is less than 1.0.