Fast Company - René Descartes’s dog, Monsieur Grat (‘Mister Scratch’), used to accompany the 17th-century French philosopher on his ruminative walks, and was the object of his fond attention. Yet, for the most part, Descartes did not think very highly of the inner life of nonhuman animals.
The biologist Lewis Held at Texas Tech University believes that there could be a 'deep homology' in apparently diverse structures across species that served common functions, such as the eye. Rather than seeing these as instances of 'convergent evolution', where features pop up separately, Held and others have found evidence of certain shared underlying genetic scaffolds that produce these features in their various forms.