The Scientist Who Scrambled Darwin's Tree of Life

 

The Scientist Who Scrambled Darwin's Tree of Life

By Dave Quammen  Aug 13, 2018 ( NYT)

"Scientists studying the evolution of primitive organisms reported today the existence of a separate form of life that is hard to find in nature. They described it as a “third kingdom” of living material, composed of ancestral cells that abhor oxygen, digest carbon dioxide and produce methane.

"They constituted a “third kingdom” of living creatures because they fit within neither of the existing two, the bacterial kingdom (bacteria) and the kingdom of everything else (eukarya), including animals and plants, amoebas and fungi, you and me.

"That image, the tree, defined the shape of evolutionary thinking from Darwin’s time until the 1990s, when new discoveries following from Woese’s rebel initiative suggested that it was inadequate. ... Branches do sometimes fuse. Limbs do sometimes converge. The scientific term for this phenomenon is horizontal gene transfer (H.G.T.).

"Those were just two of three big surprises that flowed from the work and the influence of Woese — the existence of the archaea (that third kingdom of life) and the prevalence of H.G.T. (sideways heredity). The third big surprise is a revelation, or anyway a strong likelihood, about our own deepest ancestry.  We ourselves — we humans — probably come from creatures that, as recently as 41 years ago, were not known to exist. ... Our limb, eukarya, seems to branch off the limb labeled archaea."