Charles Darwin's original "tree of life" model has undergone a major overhaul, and it's now more complicated than ever.

A group of scientists from the University of California, Berkeley have revised the tree of life diagram, revealing a much more complex diversity of life on Earth.

The new diagram shows not only the relationships between living and extinct organisms — as described by Darwin in his book On the Origin of Species — but also a trove of newly discovered bacteria and microorganisms.

Hidden Microbial Biodiversity

Trees of life are traditionally built upon three main trunks: eukaryotes, bacteria and archaea. Eukaryotes include animals and plants, while archaea, like bacteria, are single-celled microorganisms that live in extreme environments.

Biologists who have been looking to add new branches to the tree have often become unsuccessful in doing so because of the difficulty of creating some of the odd microorganisms in laboratories.

Rather than trying to isolate them individually in petri dishes, however, Berkeley scientists have resorted to sequencing their genomes, accurately including about 1,000 new types of bacteria that exist for a short while in inhospitable places. Some of these places include the Atacama Desert in Chile and the boiling hot springs at the Yellowstone National Park.

Much of the microbial biodiversity that Berkeley scientists discovered remained hidden until this incredible genome revolution.

The revised tree of life shows the enormous number of organisms on our planet. The branch that represents all known plants and animals is separated in the bottom right of the model, while the rest depicts invisible bacteria and microorganisms.

Most of the organisms cannot be cultured and isolated because they cannot live on their own, researchers said.

Why is the Tree of Life Important?

Jill Banfield, a professor of Earth Science at Berkeley, said the new rendering of the tree offers a fresh perspective on the history of life itself.

"The tree of life is one of the most important organizing principles in biology," she said.

With that, the new illustration will be helpful to biologists who investigate microbial ecology, to biochemists who are searching for new genes, as well as to researchers who study earth history and evolution.

The new tree of life is published in the journal Nature Microbiology on April 11.