early hominid?

Discussion in 'Human Science' started by sculptor, Oct 20, 2017.

  1. iceaura Valued Senior Member

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    No, we don't. The footprints in Crete are of fully bipedal hominins.
    Or the closer to Africa the more human-like the ape.
     
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  3. Gawdzilla Sama Valued Senior Member

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    And two sets of footprints prove that two groups walked in those areas. They imply a few things, but not anything that stands on its own merits except the information that can be gleaned for the footprints themselves.
     
    Last edited: Oct 26, 2017
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  5. sculptor Valued Senior Member

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    Interesting what millions of years of evolution and a few thousands of miles of migration will show us?
     
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  7. iceaura Valued Senior Member

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    No evidence of migration of individual non-bipeds, or even non-bipedal species, appears. Evidence of the northernmost extension of the range of chimpanzee progenitors appears - back when Europe included some prime ape habitat.
     
  8. Yazata Valued Senior Member

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    There's new evidence of the reality of that leakage that I was hypothesizing about:

    http://science.sciencemag.org/content/358/6368/eaai9067


    Abstract
    The traditional “out of Africa” model, which posits a dispersal of modern Homo sapiens across Eurasia as a single wave at ~60,000 years ago and the subsequent replacement of all indigenous populations, is in need of revision. Recent discoveries from archaeology, hominin paleontology, geochronology, genetics, and paleoenvironmental studies have contributed to a better understanding of the Late Pleistocene record in Asia. Important findings highlighted here include growing evidence for multiple dispersals predating 60,000 years ago in regions such as southern and eastern Asia. Modern humans moving into Asia met Neandertals, Denisovans, mid-Pleistocene Homo, and possibly H. floresiensis, with some degree of interbreeding occurring. These early human dispersals, which left at least some genetic traces in modern populations, indicate that later replacements were not wholesale.


     
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  9. Write4U Valued Senior Member

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    7,887
    Apparently Robert Hazen was correct in his proposition that life may not have had a single origin but that on an earthlike planet with the combinatory richness of available chemicals, space, time, and climate, the probability of life originating in several places or at different times might well have been possible.

    He estimated that during the lifetime of earth there may have been some 2 trillion, quadrillion, quadrillion, quadrillion chemical interactions and even if life is a rare event, these numbers would almost surely produce sufficient numbers of bio-chemicals resulting in the formation of self replicating strands of bio-polymers in several different places, which also may account for the bio-diversity we find today among species, even if such an event would occur once every 100 billion, quadrillion, quadrillion, quadrillion
    chemical interactions, there would still be 20 separate, but identical events.

    At deep ocean vents we find organisms which do not need sunlight, cuttlefish have greenish blood because the don't use iron as the oxygen carrier in their blood cells, lobsters DNA grows 2 complete but opposite halves which is completely different than the instructions contained in the DNA of most other animals.

    While the physiology of the LUCA (last universal common ancestor) is assumed to be the origin of all life on earth, it is possible that all life on earth did not necessarily come from a single point of origin but that LUCA may have formed in several different locations or times and have no direct connection to each other except a fundamentally similar bio-chemistry, which chemically is not impossible. Chemical interactions are the same throughout the universe under similar but not necessarily identical conditions. Hazen noted that chemical reactions take place in outer space by various types of radiations splitting atoms or even forming bio-molecules from chemical reactions to such radiation bombardments. From Wiki
    IOW, the bio-chemistry which produced the first self replicating bio-organisms LUCA on Earth may not necessarily have had a single point of origin, but could have occurred spontaneously in several locations, each giving rise to separate evolution of unrelated species, still having similar but unrelated origins.

    I know this is speculative, but considering the enormous variety of life on earth, to me this does not sound like pure woo, but may well be a distinct possibility.

    Can anyone comment why this could not have happened that way?
     
    Last edited: Dec 13, 2017
  10. Gawdzilla Sama Valued Senior Member

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    We don't have the burden of proving a negative. So, why would it happen that way?
     
  11. Write4U Valued Senior Member

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    Because it is a real possibility, which has been completely discarded by a false assumption that a specific chemical event can only happen in a specific singular location. Check out Robert Hazen lecture on "Chance, Necessity and the Origins of life"

    Start watching @ 25:00 into the clip to avoid the introduction.
     
  12. Yazata Valued Senior Member

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    4,897
    Sure, it certainly sounds possible. A lot depends on how we define 'life'. Life today, even the simplest bacterial life, is the end-product of what must obviously have been a long combination of hugely complex and still unknown origin-events. Life has its genetic code, its cellular morphology (cellular membranes, cell walls etc.), the system of protein synthesis with its mRNA, tRNA, RNA editing processes and ribosomes/ribozymes., elaborate energy metabolism and cellular synthetic operations, and all the rest of it. You don't just throw a bunch of chemicals together, shake them up and get something like that. It really looks like something that originated step-by-step.

    The various ingredients of those many steps might have originated separately, in rather different circumstances, sure. But I think that the whole origin process that resulted in the first living bacteria-like cell only seems to have gone all the way to completion once (here on Earth).

    The thing is, all life on Earth, from crude bacteria to human beings, all have DNA, RNA, employ the same 20 amino acids (more or less, out of some 500 known aminos total), generally speaking the same basic genetic code, generally the same protein synthesis mechanisms, and share many other chemical similarities in common (such as common energy metabolism pathways). That suggests to most observers that all of it derives from a common origin. If there were multiple totally separate origins of living cells, one would probably expect deeper and more fundamental differences in the cellular biology and chemistry.

    But that being said, the fundamental chemistry isn't 100% the same from organism to organism. There's lots of small variation in the genetic code for example, especially in mitochondrial DNA. I'm not entirely sure what to make of that, though I'm inclined to think that it is more likely the result of small differences appearing subsequent to the origin events than to totally separate origin events. Wikipedia says, "despite these differences, all known naturally occurring codes are very similar. The coding mechanism is the same for all organisms: three-base codons, tRNA, ribosomes, single direction reading and translating single codons into single amino acids."

    https://en.wikipedia.org/wiki/Genetic_code#Alternative_genetic_codes

    https://en.wikipedia.org/wiki/List_of_genetic_codes
     
    Last edited: Dec 13, 2017
  13. Gawdzilla Sama Valued Senior Member

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    I'm sure something was overlooked. I don't think we'd agree on what that is.
     
  14. Write4U Valued Senior Member

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    7,887
    I agree the formation of viable bio-organisms are indeed "rare" events. But if we consider that some (2billion, quadrillion, quadrillion, quadrillion) chemical interactions have taken place from among some 4 thousand discovered chemical compounds using relatively few elements such as carbon, oxygen, hydrogen, it is no longer a matter of extremes but rather a relatively wide range of probabilities. And as Hazen observed, biochemical reactions need not be step by step processes, the formation of fundamental cellular constructs seems to be easy and polymer structures are not rare either, it is a matter of combining already existing relatively complex bio-chemical polymer systems under the right conditions which most likely existed almost universally on earth at that time. And as Hazen said, these combinations are not necessarily the only way to arive at a viable structure. He cited three possible ways of replication methods, from which he selected RNA as the seemingly the most effective way of transferring information, but by no means the only way.

    This is why Hazen was confident there is other life dispersed throughout the universe, because of the combinatry richness on other planets which have similar fundamental chemicals over large spaces and time frames as earth. From the billions of galaxies containing trillions of stars and planets, I believe that life elsewhere has a high probability, which itself would prove that life on earth might have started at several sparate locations on earth itself.
     
  15. RADII Registered Senior Member

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    136
    Not sure why you felt compelled to add anything regarding star-forming regions. Life generally could not arise in an active nursery because the radiation would just be too extreme. Additionally, molecular clouds are either destroyed in, or not even associated with the gaseous clouds that evolve into stellar objects. Not saying 'life' couldn't evolve in a molecular cloud (said definition of 'life' having to be more than broad), but a molecular cloud could have been a source of material for panspermia, I guess...
     
  16. Write4U Valued Senior Member

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    7,887
    I think I get the gist of what that is, but if a scientist who along with many other scientists has made a lifeime study of chemicals and their possible interactions, I tend to give that more weight than any other assumption by individuals. I am not trying to negate Darwin's theory. Just that the possibility of bio-chemistry at several locations during the lifetime of earth is a distinct possiblity. You know that about 95% of all organisms once inhabiting the earth are now extinct?

    In fact that would address the theist's claim that no definitive evolutionary chain from a single location can be formed. Maybe there were several locations, where forms of life originated.
    It is an entirely reasonable argument, IMO.
     
    Last edited: Dec 14, 2017
  17. Write4U Valued Senior Member

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    7,887
    I never said that life could exist in nebular clouds, just bio-chemicals andpossibly even chemical polymers may have formed in such clouds.
    Hydrogen, Oxygen, Carbon (all essential for life as we know it) are just a few of the earliest bio-chemicals which formed relatively shortly after the BB and are now abundant elements throughout the universe.
    Watch the Hazen clip.
     
    Last edited: Dec 14, 2017

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