All present-day Life on Earth Has A Single Ancestor

Posted on June 21, 2010  Comments (3)

All present-day life arose from a single ancestor

All life on Earth shares a single common ancestor, a new statistical analysis confirms.

Because microorganisms of different species often swap genes, some scientists have proposed that multiple primordial life forms could have tossed their genetic material into life’s mix, creating a web, rather than a tree of life.

A universal common ancestor is at least 102,860 times more probable than having multiple ancestors, Theobald calculates.

For his analysis, Theobald selected 23 proteins that are found across the taxonomic spectrum but have structures that differ from one species to another. He looked at those proteins in 12 species – four each from the bacterial, archaeal and eukaryotic domains of life.

Then he performed computer simulations to evaluate how likely various evolutionary scenarios were to produce the observed array of proteins. Theobald found that scenarios featuring a universal common ancestor won hands down against even the best-performing multi-ancestor models.

Very interesting. Surprising too. As the article points out this doesn’t mean all life ever on Earth evolved from the single ancestor – life that has gone extinct could be from outside this single “tree.”

Related: Viruses and What is LifeEvolution is Fundamental to ScienceBacteria “Feed” on Earth’s Ocean-Bottom Crust

3 Responses to “All present-day Life on Earth Has A Single Ancestor”

  1. Changing Life as We Know ItCurious Cat Science and Engineering Blog : Curious Cat Science and Engineering Blog
    December 2nd, 2010 @ 8:34 pm

    NASA has made a discovery that changes our understanding of the very makeup of life itself on earth. I think my favorite scientific discipline name is astrobiology. NASA pursues a great deal of this research not just out in space but also looking at earth based life.

  2. New Analysis of Primordial Soup Experiment Half a Century Later » Curious Cat Science Blog
    March 26th, 2011 @ 6:58 am

    The simulated primordial conditions used by Miller may serve as a model for early volcanic plume chemistry and provide insight to the possible roles such plumes may have played in abiotic organic synthesis…

  3. Evolution Follows a Predictable Genetic Pattern » Curious Cat Science Blog
    November 1st, 2012 @ 8:44 am

    When things that are true just seem crazy it is a bit disconcerting – like quantum mechanics. It is fun to read stuff that totally shakes up preconceived notions, but even then it is nice once I think understand it to find it sensible…

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