Conversation so far:
Where did Terence Mckenna first study?
Terence McKenna enrolled in the University of California, Berkeley and was accepted into the Tussman Experimental College
did Terrence Mckenna graduate from UC berkeley?
In 1972, Terence McKenna returned to U.C. Berkeley to finish his studies and in 1975, he graduated with a degree in ecology, shamanism, and conservation of natural resources.
what did Terrence Mckenna do between 1965 and 1972?
In 1965, Terence McKenna enrolled in the University of California, Berkeley. In 1969, McKenna traveled to Nepal and in 1971, McKenna traveled to the Colombian Amazon
Where did Terrence Mckenna study shamanism?
Terrence McKenna Studied shamanism in Nepal

Question: when did he return to the united states?
Self-contained rewrite: when did Terrence Mckenna return to the united states?