He developed Lamarck's and Erasmus Darwin's ideas of transmutation and evolutionism, and investigated homology, even proposing that plants and animals had a common evolutionary starting point.
Desenvolveu as ideas de Lamarck e Erasmus Darwin da transmutación e o evolucionismo, e investigou a homoloxía, mesmo chegando a propoñer que as plantas e os animais tiveran un punto de partida evolutivo común.