Tangling the Tree

I’ve been fascinated by this picture since I first saw it over the weekend. It’s a hint of how we may be visualizing life in years to come. As Darwin was trying to figure out how new species could evolve from old species, he began to think of evolution as a tree. He scribbled some simple branches in a notebook, and then published a more elaborate one in The Origin of Species. Darwin didn’t actually put any animals or plants on the branches of these trees; he was just thinking about the process itself. Today, though, evolutionary trees are a common sight in scientific journals, whether scientists are reconstructing the origin of a new strain of HIV or are trying to figure out how animals evolved from single-celled ancestors. But scientists have also realized that drawing trees is harder than it once seemed. Evolution, at its heart, is about changes ...