Two-billion-year-old enzyme reconstructed (IMAGE) Universität Leipzig Caption This is what a phylogenetic tree looks like whose origin (middle) goes back two billion years. The tips of the branches each represent the enzyme of a modern organism. Credit Diana Smikalla Usage Restrictions No License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.