There, he took classes in pre-Hispanic history, ethnology, and archaeology with influential teachers as Eduard Seler, Hermann Beyer, and Manuel Gamio, with whom he often debated, posing alternative interpretations.

His rigorous methods of interpretation were evident in his first essay on patolli and other pre-Hispanic games, and it was clear to his colleagues and teachers that a powerful new professional voice had arrived.

[2] Throughout his work, he sought to explain the development of Mesoamerican civilisations in terms of continuity and internal evolution, rejecting earlier theories about cultural change being the result of trans-cultural diffusion.

[3] His notable discoveries include the excavations at Monte Albán, in particular "Tomb Seven",[4] in which several gold pieces and offerings were found (now shown in the Regional Museum of Oaxaca).

His writing on the Zapotecs, based on his work at Monte Albán, proposed that they established hegemony over neighbouring peoples - a theory which was widely criticised at the time, but which was validated by the studies of others after Caso's death.