A new evolutionary link

by Half banana 8 Replies latest watchtower beliefs

  • Half banana
    Half banana

    That heroic labeller of living things, the 18th century Swede Carl Linnaeus, painstakingly grouped into discrete categories everything which grew breathed or moved. His meticulous ranking of “kinds” made the scientific examination of the living world a whole lot easier. His legacy is greatly valued and his system is still universally used today.

    However as time has unfurled, a problem arose in the observation that nature does not always agree with the human desire for rigid boundaries -- of what makes a family, genus or species. It has been observed that nature is actually a lot more fluid in its relationships.

    In the last quarter of a century there has been a new direction in taxonomy (posh word for scientific classification). We have an increasing understanding of the genomes of living things including the human species (which are multi-celled eukaryotes) down to single celled bacteria (prokaryote) and by learning the DNA of everything, we now have a scientific arbitrator to sort out which really belongs to which taxon (i.e. rank or species). It is the DNA which determines the degree of connectedness of one species, genus or family to another. It is the essential nuts and bolts of taxonomy and the essence of how evolution is described.

    Armed with this new genome tool a marvelous discovery has been made at the humble end of the ladder of life. Sometimes the “connectedness” of one branch of life is puzzling because of not having apparent genetic links but if evolution is true then they must exist.

    How did the archaic single celled critters evolve into more complex life? Well, over simplified here for the sake of brevity; some of the single celled animals arranged all their DNA into a nucleus and then (trumpet fanfare) clumped together to form multi-celled critters (some jellyfish and corals still use this method of being a composite or colony of different animals). There are also wonderful living demonstrations of other primitive cells which coalesce only when short of nourishment. (e.g. Dictyostelium discoideum- a favourite in micro biological circles!) Are you still with me?

    Nature was unwittingly exploring diversity by mutation and chance encounters due to wind movement and climate change, with chemicals, rocks, gases and divergent genomes. We have evidence such as the mitochondrial cells even in us, we have taken on board as it were, alien life and incorporated it into our hominine genome. Some of you Trekkies will remember the “symbionts”, yes humans have actual microscopic symbionts functioning in every one of our cells and so did the early forms of complex life. Symbiotic life, absorbed because it was useful to the host and later adopted as part of the geneome.

    This understanding (admittedly my crude description of it) gives a part explanation to the matter of how increasing complexity arose in the earliest, single celled life which was the only game in town for billions of years.

    Recently Japanese researchers according to New Scientist, have found something else. Noticing a familiar DNA signature in a marine deposit they were struck by the fact that it came from a prokaryote, the DNA was previously identified only with more complex life. Bingo! As unlikely this chance find is, they seem to have found that rarest avian: a missing link, i.e. the genetic inheritance factor between the prokaryote and the eukaryote. This is DNA from one of the simplest life forms which ultimately connects it to all which followed including mammals and therefore us. It is exactly what evolution theory would predict.

  • Jofi_Wofo
  • JimmyYoung

    You mean they found the dumb gene that Democrats come from?

  • cofty

    Half Banana - Do oyu have a link to the discovery by the Japanese scientists that you refer to please?

    Endosymbiosis is a classic example of how science works at its best. It was rejected for many years until Lynne Margulies (wife of Carl Sagan I think) and her colleagues mustered sufficient evidence.

  • iwantoutnow

    COFTY - She was Carl's first wife, divorced in 65, Ann Druyan was Carl's wife till he died.

  • Half banana
    Half banana

    Cofty, I read it in a recent New Scientist. I'll give details when I have found it again.

  • Phizzy

    Thanks Half Banana, a clear and understandable exposition for a dumbass like me. I love seeing Science in action this way, the more we get to understand the more advancement to better things is possible.

    It is also pleasing to me that yet another silly argument by Creationists has been done away with. The Theory of Evolution just gets stronger with each discovery in the field.

  • Half banana
    Half banana

    @ CoftyThe information on the Japanese scientific finding was in the 25th Jan New Scientist, p16.

    Today's issue, 1st Feb, has a lot to say on endosymbiosis, especially how RNA from viruses get transmitted to eukaryotes by splicing inside a host cell, p16.

    But on p44 is Colin Barras' article "Meet your long lost ancestors". It also refers to the Asgard microbe (Prometheoarchaeum syntrophicum) which the Japanese found and cultivated, and speculate that its 'tentacle' structures could have been used to incorporate bacterial genes. I haven't mentally digested the article yet but it importantly discusses the matter of kingdoms ranking and the possibility of a three or two domain tree instead of four going all the way back to archaea.

  • cofty

    Thank you HB. Great stuff.

    I love to hear about developments in early life research.

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