Complex sentence: French's Ph.D. work at Columbia University involved studying under Ralph Linton and Ruth Benedict (he was Benedict's research assistant) and being heavily influenced by the milieu surrounding Franz Boas, who died while French was at Columbia.
Split into simpler sentences: French's Ph.D. work at Columbia University involved studying under Ralph Linton and Ruth Benedict (he was Benedict's research assistant). He was heavily influenced by the milieu surrounding Franz Boas, who died while French was at Columbia.