Has the Origins of Human Life on Earth Been Discovered?

Discussion in 'Science and Technology' started by Dryson, Aug 17, 2021.

  1. Santaman

    Santaman Vice Admiral Admiral

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    Hmm.. of course iron in metallic form is really rare, it is usually only found as an ore and bound to oxygen, might be why it isn't in our RNA, DNA, ATP, GTP and so on, but is is a really critical element in our bodies, the whole cellular respiration system relies on it.
     
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  2. Dryson

    Dryson Fleet Captain Fleet Captain

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    Therefore, whenever metallic atoms became consumable and digestible by biologicals on Earth, that point should be the moment when life on Earth changed, but not just on Earth.

    The key question is, when would metallic atoms have been the correct portion to be consumed?

    Is there a method of tracking the percentage of metallic atoms found in the human body to a point in Earth's past when the same exact percentage of metallic atoms would have been present on Earth?
     
  3. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    The iron-sulfur world hypothesis proposes that early life may have formed on the surface of iron sulfide minerals in deep-sea volcanic hydrothermal vents. A variation on this hypothesis is that life evolved inside alkaline vents containing membranous metal sulfide cavities. Yet another proposes freshwater hot springs containing clay minerals and metallic sulfides. Having the right environment to develop precursors to the molecules needed for metabolism and encoding genetic information and keeping these stable is the difficult part to model.

    The first life didn't use oxygen in its metabolism - it likely ingested hydrogen sulfide and released sulfate - although other possible anoxic metabolic pathways are known. Aerobic cellular respiration is likely derived from something akin to purple bacteria that had evolved this form of respiration from the sulfur-based form to exploit rising oxygen levels. These bacteria later became co-opted as the mitochondria of eukaryotic cells.

    Early earth didn't have much free oxygen so iron was usually in its Fe(II) state, which is more soluble in water than Fe(III). When cyanobacteria started releasing significant oxygen, the iron dropped out of solution as Fe(III) in iron oxide - hence the banded iron formations formed, peaking about 2.4Ga ago.
    Banded iron formation - Wikipedia
     
    Last edited: Dec 3, 2021
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  4. Santaman

    Santaman Vice Admiral Admiral

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  5. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    Yeah, it does seem like accidental terraforming.

    Living cells use adenosine triphosphate (ATP) molecules to drive many processes. ATP is the molecular unit used to transfer energy within cells. In a way, each ATP works like a battery. It can provide one jolt of energy to power a chemical process before it needs to be recharged. One mole (6.022 x 10^23 molecules) of ATP has a mass of about 0.5 kg and provides the equivalent of 7.6 kilocalories of energy (31.8 kilojoules) or about the calorific content of a stick of celery. The human body uses approximately its weight in ATP each day, which requires each ATP in the body to be recharged about 1000 times. A human body typically contains about 75 grams of ATP. Each cell in the human body is estimated to use about 25 million ATPs per second, or roughly 10^21 per second for the entire body.

    Without oxygen, life would still be using inefficient forms of respiration. Aerobic respiration can turn between 36 and 38 molecules of ADP into ATP for every one glucose molecule. The respiration processes of glycolysis and the Krebs Cycle on their own, without the electron transport chain and ATP synthase in mitochondria, can only produce 4 ATP molecules per glucose molecule by phosphorylation.

    Mitochondrion - Wikipedia
     
    Last edited: Dec 6, 2021
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  6. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    New post to recommend David Deamer's latest popular science book, published last year, on the origin of terrestrial life:

    Origin of Life: What Everyone Needs to Know

    It's only a hundred pages long so it's a short read but it covers all the basics.

    Some of the phosphorus vital for life's molecules might originate from cosmic dust in the solar system:



    Phosphorus is a crucial element, particularly in DNA, RNA, ATP, and phospholipids - along with carbon, nitrogen, oxygen, and hydrogen, of course. Another vital element is sulfur, which is found in fats, bodily fluids, and skeletal minerals and is a key component of proteins such as keratin, insulin, and collagen via the amino acids methionine and cysteine. The abundance of elements in the human body and their biological roles are listed on the following Wikipedia page:

    Composition of the human body - Wikipedia
     
    Last edited: Dec 6, 2021
  7. Dryson

    Dryson Fleet Captain Fleet Captain

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    Would studying melanin help track down the point at which life progressed into sentients on Earth?

    Darker skin tones have more melanin than lighter ones, meaning they’re better protected from the sun. But melanin isn’t immune to all UV rays, so there’s still some risk.

    https://www.healthline.com/health/can-black-people-get-sunburn#sunburn-risk

    Darker skin toned peoples might have been around during a period of when the Earth was forming where there was more UV penetrating the clouds of the Earth. UV penetration protection that would be needed to protect the internal organs from catastrophic damage. As the UV rays subsided, so did the need for more melanin which could then have resulted in an evolutionary shift to lighter toned people. Just like humans shod their hair as the Earth got warmer, so to would humans have shod their skin color when the ozone of the Earth developed enough to block out harmful UV.

    Other factors - Dark-skinned people need six times more sun than white-skinned people to get enough Vitamin D. On the other hand, they have less chance of developing skin cancer.

    https://www.mn.uio.no/fysikk/english/research/news-and-events/news/2011/why-skin-colours-differ.html

    Although darkly-pigmented skin absorbs about 30 to 40% more sunlight than lightly-pigmented skin, dark skin does not increase the body's internal heat intake in conditions of intense solar radiation.

    I was thinking that dark toned people might have also have been darker due to the need of protecting the body from harmful UV along with absorbing more heat from the Sun so that when the humans huddled close together in caves, before the discovery of and mastery of fire, to keep warm, thus putting early humans at a point in Earths evolution somewhere around the time when the Ozone was only partially formed as well as being in places where humans face hot days and cold nights.

    The question is, did darker toned people of the past retain heat for much longer periods of times during colder weather while radiating heat during the day?
     
  8. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    From molecular evidence, the Haplorhini (dry nosed) and the Strepsirrhini (wet nosed) primate clades probably diverged between 63 and 74 million years ago. We don't know what the crown group was but its unlikely to be much older. The radiation of mammals followed the mass extinction event at the end of the Cretaceous, 66 million years ago. No primate fossils are known prior to the beginning of the Eocene, 56 million years ago. In any case, that's a lot more recent than the development of multicellular eukaryotic life, perhaps 600 to 700 million years ago, or life itself, perhaps 3.5 to 4.0 billion years ago. The Hominid family arose between 15 and 20 million years ago and the genus Homo about 2.5 million years ago. Homo sapiens sapiens is the new kid on the block, thought to have evolved sometime between 160,000 and 90,000 years ago in Africa.

    Skin colour affects body temperature. Humans living closer to the Equator have more melanin in the skin, which makes the skin darker, protects it from UV damage and increases sensitivity to heat. Heightened heat sensitivity acts a warning to avoid exposure to sunlight.
    Team discovers that skin color affects skin sensitivity to heat, mechanical stimuli (medicalxpress.com)

    However, melanin also restricts vitamin D synthesis so humans farther from the Equator, where exposure to sunlight is reduced, tend to have less melanin in their skin. This is a bigger driving factor for survival than retaining or losing heat - after all, we handy humans can fashion clothes to keep warm or shed them to cool down by sweating, which we are very good at - unless you're Prince Andrew.

    Regarding the adaptive effects of melanin production on human evolution, here's one paper on the subject:
    The evolution of human skin coloration - PubMed (nih.gov)

    However, there are many more research papers on the subject as cited on that webpage. All I can do is suggest that you spend time to read the literature extensively so that you can hone your thesis.
     
    Last edited: Dec 17, 2021
  9. 'Q'

    'Q' Lieutenant Commander Red Shirt

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    Since darker skinned folk originally came from equatorial region, UV exposure was not the only driver. One thought is that darker skin was also beneficial against fungal and mold infections that are more prevalent in hot, humid climate zones.
     
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  10. Dryson

    Dryson Fleet Captain Fleet Captain

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    ...we handy humans can fashion clothes to keep warm or shed them to cool down by sweating...

    Humans, at one point in time in the past, would have walked around naked, all of the time, until the need for clothing arose due to colder climates.

    Could humans have had a starting point sometime when the continents were still fairly close together? At what point in the continental drift of the continents would humans have needed to wear clothes to survive the ravages of cold nights?
     
  11. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    The Atlantic Ocean widens by about 25 miles per million years. That's pretty slow going. It would have only widened by some 100 miles since the time that Australopithecus evolved, just over 4 millions years ago. Altitude above sea level, local climate variation, and the ice ages would have had a greater effect as would the Messinian salinity crisis between 5.96 and 5.33 million years ago when the Mediterranean Sea dried up due to the closure of the predecessor to the Strait of Gibraltar. It can also get pretty chilly at night if there is no cloud cover - even near the Equator.

    Fire as well as clothes can also be used to ward off the cold. It's though that the means of making fire were invented somewhere between 700,000 and 120,000 years ago. The first use of clothes is estimated to be some 170,000 years ago, round about the end of the second-to-last ice age. The Neanderthals perhaps were wearing clothes over 400,000 years ago.

    When did humans first start wearing clothes? - BBC Science Focus Magazine
     
    Last edited: Dec 19, 2021
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  12. Dryson

    Dryson Fleet Captain Fleet Captain

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    (CNN)The oldest family tree in the world has been reconstructed through the analysis of ancient DNA taken from a Stone Age tomb in Britain, according to a new study published Wednesday.

    Researchers extracted DNA from the bones and teeth of 35 individuals buried at Hazleton North long cairn in the Cotswolds-Severn region, England. They found that 27 of them were close biological relatives and were from five continuous generations of a single extended family.
    The group lived around 3700-3600 BC -- approximately 5,700 years ago. Researchers discovered that most of those buried in the tomb were descended from four women who had children with the same man.

    https://edition.cnn.com/2021/12/22/uk/worlds-oldest-family-tree-scli-scn-intl-gbr/index.html?utm_source=fbCNN&utm_medium=social&utm_term=link&utm_content=2021-12-23T07:01:02&fbclid=IwAR04EyPRVSbrgZplDJV1dOxWZbFe1wIDo2P-QP9yEKzApZyCpANKoVWOreI

    The empire of Sumer is the earliest known civilization.

    I went down this list and here are the Top Five civilizations that are closest to Sumer within 3,000.

    https://en.wikipedia.org/wiki/List_of_empires


    1. Assyria at 2,500 years https://en.wikipedia.org/wiki/Assyria
    2. Akkadin at 2,334 years https://en.wikipedia.org/wiki/Akkadian_Empire
    3. Manchuko at 1934 years https://en.wikipedia.org/wiki/Manchukuo
    4. Belgian at 1,901 years https://en.wikipedia.org/wiki/Belgian_colonial_empire
    5. Babylon at 1,900 years https://en.wikipedia.org/wiki/Babylonian_Empire


    Sumer (/ˈsuːmər/)[note 1] is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is also one of the first civilizations in the world, along with ancient Egypt, the Caral-Supe civilization, the Indus Valley civilization, the Minoan civilization, and ancient China. Living along the valleys of the Tigris and Euphrates, Sumerian farmers grew an abundance of grain and other crops, the surplus from which enabled them to form urban settlements. Proto-writing dates back before 3000 BC. The earliest texts come from the cities of Uruk and Jemdet Nasr, and date to between c. 3500 and c. 3000 BC.[1]

    This newest discovery will put the ancients of the UK well into the Iron Age along with the top five oldest empires during the Iron Age.

    The environment of the Earth during the Iron Age could be used as a determinate. Being that humans had started to use iron tools 5,700 years, at least, if we are able to detect a planet that is habitable with the JWST, and then compare the environments and age of the planet to the Earths and then, roll back the habitable planets time line of evolution until the environment patterns are similar to Earth's during the Iron Age, we could at least expect to find Iron Age castes of humans.

     
    Last edited: Dec 23, 2021
  13. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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  14. Nerys Myk

    Nerys Myk Worf In the 23rd Century Premium Member

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    Looks like he confused the start date with the duration.
     
  15. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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    Really, it's not worth taking the time to type our responses.
     
  16. Dryson

    Dryson Fleet Captain Fleet Captain

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    The dates I listed are years, B.C.

    Lions live in savanna regions which have temperatures between 20 and 30 degrees Celsius.
    Yes, lions shed in the spring to get a thinner coat to help keep cool.


    Humans don't have fur any longer because humans have evolved to build houses to live in that block out harmful UV and keep us warmer compared to the lions that live outdoors, all of the time.

    If humans still lived outside and only had caves to live in, would we still have some fur covering for sleeping during the night to keep us warm? Would we shed our fur during the hotter times of the year?

    Could humans have evolved before modern day lions did?
    Could lions have migrated from a region of the Earth that was colder, much colder than the Savanna?

    Could lions have chased humans out of colder regions into much warmer regions. Science has already proven that lions will attack and eat a human as if the human was a gazelle and not a last resort meal.

    Man-eating lions studies indicate that African lions eat humans as a supplement to other food, not as a last resort. In July 2018, a South African news website reported that three rhino poachers were mauled and eaten by lions at Sibuya Game Reserve in Eastern Cape province, South Africa.

    Ah...

    The first signs of hairlessness were seen about 1.2 million years ago with the Homo erectus species that started to lose more and more of their fur and develop their skin pigment.

    https://historyofyesterday.com/why-...f hairlessness,and develop their skin pigment.

    So, 1.2 million years the pigment of humans was still developing.

    What would the environment of the Earth have been like 1.2 million years ago? Hot? Cold? High UV saturation?
     
  17. Asbo Zaprudder

    Asbo Zaprudder Admiral Admiral

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  18. Nerys Myk

    Nerys Myk Worf In the 23rd Century Premium Member

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    No, they weren't look the articles you linked.
     
  19. Santaman

    Santaman Vice Admiral Admiral

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    ^^ He's like a science terminator, can't reason with it, can't use logic on it.. :p
     
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  20. Finn

    Finn Bad Batch of TrekBBS Premium Member

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    :cardie:

    No. Just no.