900 Years of Tree Diagrams, the Most Important Data Viz Tool in History. Trees are a data viz tool that has outlived empires and endured huge upheavals in the arts and sciences.

So, you can read a tree diagram like a picture story of evolutionary history. The trunk of the tree is the ancestral line, made up of generation after generation of the same type of organisms.

The tree diagram, in particular, has its roots in the Middle Ages. “In Medieval Europe, 800 years ago, visual communication was critical,” Lima says, drawing from his book, which examines the ...