The hat tip for this image goes to Carl Zimmer at The Loom, posting about Google Earth as an analogy in his new article that discusses how phylogenies between gi-normous numbers of related organisms can be mathematically and visually represented. The image itself is from this public page from the David Hillis Lab at UT Austin, who it seems may have taken it from this article in Science. The author describes it this way: “A sketch of the tree of life itself is shown on p. 1694. Far from a final answer, it illustrates how complex a unified tree of life will be.” The tree is based on ribosomal RNA, one of many types of molecular phylogenies, each with its own advantages and disadvantages.
Ok, see the stuff that looks like fuzz around the outside of the circle? Those are the names of the organisms whose positions are represented by the spiraling lines. I’ve blown it up a little bit so you can see a fragment of the chart that includes our own dear selves, snuggled comfortably between the common mouse and the Sicilian Worm (which isn’t a worm, but an odd little worm-looking amphibian).
We are one of only four mammals to grace the chart. This chart is only an illustration – really an illustration of the difficulty of mapping more extant species. What’s really mind blowing to me is to know that only four mammal species are included. That means they left out multiple species each of squirrels, raccoons, possums, elephants, giraffes, horses, donkeys, dogs, cats, lemurs, chimpanzees, monkeys, dolphins, whales, … and I could keep going all day – just of one class of organisms extant today. Imagining a picture like this that came anywhere near representing all extant species is an exercise in futility for me. You Are Here becomes a vanishingly small spot.
Oh yeah – you can download, zoom in & print the chart as pdf (if you’re printing, they recommend 54″ wide paper): here.
Update: More comments from Zimmer here.