It was long ago that poly­the­ism, as the sto­ry comes down to us, gave way to monothe­ism. Human­i­ty used to have many gods, and now almost every reli­gious believ­er acknowl­edges just one — though which god, exact­ly, does vary. Some pop­u­lar the­o­ries of “big his­to­ry” hold that, as the scale of a soci­ety grows larg­er, the num­ber of deities pro­posed by its faiths gets small­er. In that scheme, it makes sense that the grow­ing Roman Empire would even­tu­al­ly adopt Chris­tian­i­ty, and also that the gods it first inher­it­ed from the city-states of ancient Greece would be so numer­ous. Through our mod­ern eyes, the var­i­ous immor­tals invoked so read­i­ly by the Greeks look less like holy fig­ures than a cast of char­ac­ters in a long-run­ning tele­vi­sion dra­ma. Or maybe it would have to be a soap opera, giv­en that most of them belong to one big, often trou­bled clan. Hence the struc­ture of Use­fulCharts’ Greek Mythol­o­gy Fam­i­ly Tree, explained in the video above. Also avail­able for pur­chase in poster form, it clear­ly dia­grams the rela­tion­ships between …