Ernst Haeckel's "Tree of Life" from his 1879 book The Evolution of Man, which depicts a literal interpretation of Charles Darwin's metaphorical description of the pattern of universal common descent. In early evolutionary thought, humans were considered the pinnacle of evolution, and thus "Man" is at the crown of the tree. In the modern synthesis, evolution is understood to be an ongoing process with no defined endpoint. The tree of life is still considered valid for eukaryotes, but prokaryotic life forms are capable of horizontal gene transfer, meaning that the concept gives an incomplete picture of life's evolution.Restoration: Ragesoss