A couple years back, Mongolian-Swedish twentysomething Yänjaa Wintersoul became IKEA’s first “human catalog.” It was an impressive performance of both human cognition and viral marketing: Yänjaa committed IKEA’s full annual catalog to memory, down to every last Ektorp, Kallax, and Fejka. Yänjaa, a triple world-record-holding memory champion, polyglot, and multi-hyphenate…