Tree of Life | Origins

The Puzzle
In the 1960's, most scientists believed drawing a new tree of life by comparing the genetic codes of different species was too difficult. DNA is very complex with thousands to millions of pieces, and a comparison of the DNA between thousands of species was practically impossible with the current technology.

But Dr. Carl Woese, a molecular biologist in Urbana, Illinois, believed he could change that. To compare different species, he looked at a special chain of genetic material that exists in a very similar form inside every living thing: RNA. He also focused initially on the evolution of the most primitive forms of life, microbes.

For each species he placed on his tree, Woese collected strands of its RNA. Then he developed x-ray photographs of the individual RNA sections, collecting fragments of the organism's genetic code. Comparing thousands of these x-ray photos from different species, Woese began to see how life forms that shared common sections of RNA could form small groups. Eventually these smaller groups could be joined into larger groups. In the end, he had a full tree displaying how the RNA of different species developed since the earliest microbes.

Putting this puzzle together, Woese and other scientists had a better idea of what the genetics of the earliest microbe looked like, but they had no living example to check. A hunt began for the closest living relative of the first life on Earth.

Tree of Life | Origins

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