How food availability could catalyze cultural transmission in wild orangutans

The proverb "necessity is the mother of invention" has been used to describe the source from which our cultural evolution springs. After all, need in times of scarcity has forced humans to continually invent new technologies that have driven the remarkable cumulative culture of our species. But an invention only becomes cultural if it is learned and spread by many individuals. In other words, the invention must be socially transmitted. But what are the forces that drive social transmission?