His specialist knowledge of mammalian dentition led him to pursue the same path with regard to human evolution and he came to be regarded as the world's leading expert on the evolution of human dentition, a reputation secured by the 1922 publication of The Evolution of the Human Dentition.
O seu coñecemento especializado da dentición dos mamíferos levouno a seguir o mesmo camiño con respecto á evolución humana, chegando a ser considerado como o principal experto mundial na evolución da dentición humana, unha reputación asegurada pola publicación en 1922 de The Evolution of the Human Dentition.