I had learned that a dexterous, opposable thumb stood among the hallmarks of human success. We had maintained, even exaggerated, this important flexibility of our primate forebears, while most mammals had sacrificed it in specializing their digits. Carnivores run, stab, and scratch. My cat may manipulate me psychologically, but he'll never type or play the piano.

Examples include the "masculinized genitalia in female hyenas exaptive use of an umbilicus as a brooding chamber by snails the shoulder hump of the giant Irish deer and several key features of human mentality. Marriage and family
Gould was married twice. Technical work on land snails
Most of Gould's empirical research pertained to land snails.

Most of Gould's empirical research was based on the land snail genera Poecilozonites and Cerion. Many of Gould's essays for the magazine Natural History were reprinted in collections such as Ever Since Darwin and The Panda's Thumb. He also contributed to evolutionary developmental biology and has received wide praise for his book Ontogeny and Phylogeny.