Darwin is famous for his Tree of Life hypothesis, and we talked yesterday about how his ideas predict the science of ecology (here is that Wikipedia definition):
Ecology (from Greek: οἶκος, "house" ; -λογία, "study of") is the interdisciplinary scientific study of the interactions between organisms and their environment. Ecology is also the study of ecosystems. Ecosystems describe the web or network of relations among organisms at different scales of organization. Since ecology refers to any form of biodiversity, ecologists can conduct research on the smallest bacteria to the global flux of atmospheric gases that are regulated by photosynthesis and respiration as organisms breath in and out of the biosphere. Ecology is a recent discipline that emerged from the natural sciences in the late 19th century. Ecology is not synonymous with environment, environmentalism, or environmental science.
The only image in the original On the Origin of Species is a tree diagram representing Darwin’s model for the theory of evolution. It looks like this (kind of like a musical score):
The first draft of his Tree of Life is a sketch in the little black notebook B (now at Cambridge University), from July 1837. The text reads:
Case must be that one generation then should be as many living as now. To do this & to have many species in same genus (as is) requires extinction.
Thus between A & B immense gap of relation. C & B the finest gradation, B & D rather greater distinction. Thus genera would be formed. — bearing relation (page 36 ends - page 37 begins) to ancient types with several extinct forms.
And here is that sketch on the body of a contemporary Darwin devotee (below), found at the site of Michael D. Barton ("Darwin's bulldog," writing from Bozeman, Montana), Dispersal of Darwin. Looks a bit like a wound with stitches.
There are many more Darwin tattoos, including those over at the Discover blog. Here's an impressive one of the portrait variety: "Got it at Darwin City Tattoos, in Darwin, Australia. The artist is Blue aka Mat Selwyn."