Chapter 17: The Tree of Life

Systema Naturae

Browsable English translation of Linneaus’ Systema Naturea, or a General System of Nature

(Main Idea: Linnaeus’ classification system has seven levels.)


Interactive cladogram of living things including links showing how to read cladograms

(Main Idea: Cladistics is classification based on common ancestry.)

How Cladograms Are Built

Interactive tutorial in which you build a cladogram and learn about the tools that reveal relationships among organisms

(Main Idea: Cladistics is classification based on common ancestry.)

Molecular Evidence for Relationships

Video explaining how genetic data are used to determine relatedness

(Main Idea: Molecular evidence reveals species’ relatedness.)

Molecular Clock

Program in which you type in any two species and find out how long ago scientists estimate they diverged

(Main Idea: Molecular clocks use mutations to estimate evolutionary time.)

Tree of Life

Interactive ongoing Tree of Life project, in which clicking on a group reveals its subgroups; you can find humans buried in the tree and get a sense of just how diverse life is

(Main Ideas: Classification is always a work in progress. The three domains in the tree of life are Bacteria, Archaea, and Eukarya.)