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Information about Last Universal Ancestor

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Last universal ancestor (LUA), also LUCA (last universal common ancestor), is the hypothetical latest living organism from which all currently living organisms descend. As such, it is the most recent common ancestor of the set of all currently living organisms. It is estimated to have lived some 3.6 to 4.1 billion years ago[1] .

Misconceptions

The LUA is not hypothesised as:
  1. the first living organism ever.
  2. the most primitive possible living organism.

The hypothesis

At the time when LUA was first hypothesized, construction of cladograms based upon genetic distance between all living cells indicated that there was an early split between the Archaeans and the remainder of life. This was inferred from the fact that, at that time, all known archaeans were highly resistant to environmental extremes such as high salinity, temperature or acidity, and led some to suggest that LUA evolved in areas like the deep ocean vents, where such extremes prevail today. However, since that time, archaeans have been discovered in less hostile environments and are now believed by many taxonomists to be more closely related to Eukaryotes than Bacteria, though this is still a matter of some contention.

It is possible that all of LUA's contemporaries would have since become extinct with only the LUA's genetic heritage living on to this day. However, this suggestion ignores the possibility of horizontal gene transfer. Carl Woese has proposed that there was no individual organism which could be considered a LUA, but rather that the genetic heritage of all modern organisms derives from an ancient community of organisms.[2]

See also

References

1. ^ Doolittle, W. Ford (February, 2000). "Uprooting the tree of life". Scientific American 282 (6): 90–95.
2. ^ Woese, Carl, The universal ancestor, Procedings of the National Academy of Sciences, Vol. 95, Issue 12, 6854-6859, June 9, 1998, [1]


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The origin of life guide
ScienceOrigin of life Universal common descent Last universal ancestor RNA world hypothesis Iron-sulfur world theory PAH world hypothesis
Mythology and religionOrigin belief Tree of life
Plantae
  • Chromalveolata
  • Heterokontophyta
  • Haptophyta
  • Cryptophyta
  • Alveolata

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    • The most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. The term is most frequently used of humans.
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    Life on Earth

    Life on Earth DVD cover

    Picture format 4:3
    Audio format Stereo
    Episode duration 55 minutes
    Executive producer(s) Christopher Parsons

    Presented by David Attenborough
    Music by Edward Williams
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    To help compare orders of magnitude of different times this page lists times between 1017 seconds and 1018 seconds (3.2 and 32 billion years) See also times of other orders of magnitude.
    • Shorter times
    • 3.9 to 4.

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    Cladistics is a philosophy of classification that arranges organisms only by their order of branching in an evolutionary tree and not by their morphological similarity, in the words of Luria et al. (1981).
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    Genetic distance is a measure of the dissimilarity of genetic material between different species or individuals of the same species.

    All of life today is based upon the molecule of inheritance, DNA (deoxyribonucleic acid).
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    Archaea
    Woese, Kandler & Wheelis, 1990

    Phyla

    Crenarchaeota
    Euryarchaeota
    Korarchaeota
    Nanoarchaeota
    ARMAN
    The Archaea (
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    Black smokers are a type of hydrothermal vent found on the ocean floor. The vents are formed in fields hundreds of meters wide when superheated water from below the Earth's crust comes through the ocean floor. It can also be known as a Sea Vent.
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    Bacteria

    Phyla

    Actinobacteria
    Aquificae
    Chlamydiae
    Bacteroidetes/Chlorobi
    Chloroflexi
    Chrysiogenetes
    Cyanobacteria
    Deferribacteres
    Deinococcus-Thermus
    Dictyoglomi
    Fibrobacteres/Acidobacteria
    Firmicutes
    Fusobacteria
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    extinction is the cessation of existence of a species or group of taxa, reducing biodiversity. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point).
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    Horizontal gene transfer (HGT), also Lateral gene transfer (LGT), is any process in which an organism transfers genetic material to another cell that is not its offspring.
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    Carl Richard Woese (born July 15 1928, Syracuse, New York) is an American microbiologist famous for defining the Archaea (a new domain or kingdom of life) in 1977 by phylogenetic taxonomy of 16S ribosomal RNA, a technique pioneered by Woese and which is now standard practice.
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    timeline of the evolution of life outlines the major events in the development of life on the planet Earth. For a thorough explanatory context, see the history of Earth, and geologic time scale. The dates given in this article are estimates based on scientific evidence.
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    The most recent common ancestor (MRCA) of any set of organisms is the most recent individual from which all organisms in the group are directly descended. The term is most frequently used of humans.
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    Superscript text

    Last Common Ancestor (LCA) is the most recent common ancestor of two populations that came to be separated by a species barrier.

    LCA of Humankind


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    origin of life, is the study of how life on Earth might have emerged from non-life. Scientific consensus is that abiogenesis occurred sometime between 4.4 billion years ago, when water vapor first liquefied,[2] and 2.
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    A group of organisms is said to have common descent if they have a common ancestor. In modern biology, it is generally accepted that all living organisms on Earth are descended from a common ancestor or ancestral gene pool.
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    RNA world hypothesis is a theory which proposes that a world filled with RNA (ribonucleic acid) based life predates current DNA (deoxyribonucleic acid) based life. RNA, which can store information like DNA and
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    The iron-sulfur world theory is a hypothesis for the origin of life advanced by Günter Wächtershäuser, a Munich chemist and patent lawyer, involving forms of iron and sulfur. Wächtershäuser proposes that an early form of metabolism predated genetics.
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    The PAH world hypothesis is a biological hypothesis that proposes that the use of polycyclic aromatic hydrocarbons (PAH) was a means for a pre-RNA World basis for the origin of life. As yet it is untested.
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    The Raven and The First Men, showing part of a Haida creation story. The Raven represents the Trickster figure common to many mythologies. The work is in the University of British Columbia Museum of Anthropology, Vancouver.
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    tree of life is a mystical concept, a metaphor for common descent, and a motif in various world theologies and philosophies.

    Conceptual and mythological "trees of life"

    Various forms of trees of life
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