All life on Earth (bacteria, archaea, eukarya) is thought to have evolved from a common ancestor, or last universal common ancestor (LUCA). What do we know about the characteristics of LUCA based upon extant life?

  • 4
    $\begingroup$ Wikipedia's article does a pretty fair job of summarizing the likely nature of the LUCA. $\endgroup$
    – mgkrebbs
    Commented Mar 20, 2012 at 4:35
  • 1
    $\begingroup$ Seems rather broad at the moment. Perhaps one should constrain the question? $\endgroup$
    – bobthejoe
    Commented Apr 15, 2012 at 18:54

1 Answer 1


Carl Woese has much to say on this subject, including:

“The ancestor cannot have been a particular organism, a single organismal lineage. It was communal, a loosely knit, diverse conglomeration of primitive cells that evolved as a unit, and it eventually developed to a stage where it broke into several distinct communities, which in their turn become the three primary lines of descent [bacteria, archaea and eukaryotes].”

There is a 2000 Scientific American article by W.F. Doolittle that discusses much of Woese's (and others') work understanding this question.

Also, see a couple of Woese articles here and here.


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