To Draw a Tree
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Typical infovis methods: treemap, cone tree, hyperbolic viewer.

Other tree drawings: tournaments, genealogy.

Cell differentiation (C. elegans): drawn anterior to posterior on worm.

Evolutionary trees (spindle diagrams): curvature of lines is important!
Thickness represents species population.  History of rock and roll.

Best diagrams don't use space in an arbitrary, abstract way.
Space is used to represent a quantitative variable like time or
population or total sales.

Furbringer: since phenotypic change is not one-dimensional, he drew
a three-dimensional tree and gave cross-sections.  Cross-sections
give Venn-like subsetting relationships.

Evolutionary trees: how to represent uncertainty and consensus?
Non-binary lines, thickness, enveloping trees.

Comparing trees.  co-evolution of symbiotic organisms.

Shape of the tree shows the pattern of evolution: diversify & decimate?
Position humans at the top?  Arbitrary layout decisions affect science.
Iconography of processes reveals modes of thinking not described in text.

Hierarchical databases.  Pivot tables.  Polaris: tree generator.
Star and snowflake schemas.  Data cubes.

Themes: diagrams exist in specific domains, not in a vacuum.

Tversky's principles.  *Congruence Principle*: The structure and
content of the external representation should correspond to the
desired structure and content of the internal representation.
*Apprehension Principle*: The structure and content of the external
representation should be readily and accurately preceived and
comprehended.

Must survey much better the space of designs.  Why so little
intersection between historical illustrations and info vis?
Best metaphors have been refined over time and have stood the
test of time.  Need to understand and appreciate what makes
metaphors effective.  (Heuristics like minimizing space are
too simplistic.)  It takes both creativity and experience,
algorithms and aesthetics, to create new metaphors.  Often, one
element is lacking.  Tufte: "graphical excellence is multivariate",
therefore, mix your metaphors.

Challenge: all the best visualizations are still designed by humans.
But computer-mediated communication is now ubiquitous.  Therefore,
visualizations are regressing.

Distinction between exploratory and persuasive graphics.  Not just
about artists; these were scientists expressing their observations.
Need an understanding of the embedding to do exploratory visualization.

References: Haeckel's History of Creation, Scenes from Deep Time.