Evidence of common descent of living organisms has been discovered by scientists researching in a variety of disciplines over many decades and has demonstrated common descent of all life on Earth developing from a last universal ancestor. This evidence explicates that evolution does occur, and is able to show the natural processes by which the biodiversity of life on Earth developed. Additionally, this evidence supports the modern evolutionary synthesis—the current scientific theory that explains how and why life changes over time. Evolutionary biologists document evidence of common descent by making testable predictions, testing hypotheses, and developing theories that illustrate and describe its causes.