Charles Darwin famously created a sketch of an evolutionary tree in a notebook in 1837, and used the expression 'tree of life' in his 1859 book, On the Origin of Species.

"As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever-branching and beautiful ramifications."

Later, in the late 19th century, Ernst Haeckel popularised the use of tree diagrams to show evolutionary relationships of organisms further in his publications that attempted to organise all life on Earth.

Nevertheless, tree diagrams had been used to organise knowledge before Darwin. In the early 1800s botanists such as Antoine-Nicolas Duchesne and Nicolas Charles Seringe used branching diagrams to describe plants. Even far back in history, the ancient Greek philosopher, Aristotle had ranked animals and plants in his History of Animals in the fourth-century BCE.

The tree of life today

Early approaches to organising the present and past diversity of life in tree diagrams relied on physical characteristics of organisms. Today, scientists can also use molecular data, such as genes and proteins, to shed light on the relationships of organisms. The tree of life presented in the Museum's display is just one way to represent how all known life is connected through evolution. This representation keeps changing as our understanding on the relationships between organisms improves.