What did life on earth look like 4 billion years ago?
What did life on earth look like 4 billion years ago? This photo shows fossil-like rock found in Australia containing hints of life from 4.1 billion years ago. Life on a near primordial Earth may have been around 4.1 billion years ago, 300 million years earlier than thought, hints a chemical fossil-like rock found in Australia. It also gives more hope for life elsewhere in the universe. (Bruce Watson/PNAS/AP)
What did life on earth look like 4 billion years ago?
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Scientists have found fossil-like hints that some kind of life existed on Earth 4.1 billion years ago. Back then the planet was a mere volcanic toddler. That's 300 million years earlier for life to pop up than previously thought.
 
Not only does that change the way scientists thought Earth was like soon after it formed 4.5 billion years ago, but it also gives them reason to theorize that life itself is more plentiful throughout the universe. That is because it seemed to start up so quickly.
 
Researchers examined tiny grains of the mineral zircon from western Australia's Jack Hills and scientists chemically dated them to when Earth was barely 400 million years old. Inside one of the grains, they found what they call a "chemo-fossil" or a certain mix of carbon isotopes. This is according to a study published in the journal Proceedings of the National Academy of Sciences.
 
Think of it as "the gooey remains of biotic life or anything more complicated," said study co-author Mark Harrison, a UCLA geochemistry professor.
 
There are different types of carbon with different weights. This carbon residue had a higher percentage of the lighter type of carbon.  It's what scientists usually find in remnants of life, the same as if your finger decayed, Harrison said. There are rare cases where this particular carbon signature wouldn't be from life. But they are exceedingly unusual and only in certain situations.
 
Harrison theorizes that the carbon is from a colony of tiny organisms of some unknown type. Life existing 300 million years earlier than science thought is the most logical and simplest explanation. But "this is not smoking gun evidence," Harrison said.
 
The common thinking of early volcanic Earth is that it was too molten.  The belief has been that there was not enough liquid water for life to take hold this early. But, Harrison said, there's no physical evidence for this theory. What the zircon shows is "the Earth by 4.1, 4.2 billion years ago was basically behaving like it is today."
 
"This is what transformative science is all about," said Stephen Mojzsis, a University of Colorado scientist who wasn't part of the research. "If life is responsible for these signatures, it arrives fast and early."
 
S. Blair Hedges of Temple University, who also wasn't part of the study, said Harrison's findings make sense. The accelerated timeline of life fits with his own genetic tracking work.
 
"If life arose relatively quickly on Earth," Hedges wrote in an email, "then it could be common in the universe."

Source URL: https://www.tweentribune.com/article/tween78/what-did-life-earth-look-4-billion-years-ago/

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CRITICAL THINKING QUESTION
Why does the presence of water factor into scientists thinking about life on earth?
Write your answers in the comments section below


COMMENTS (36)
  • josepht-2-bar
    10/29/2015 - 10:55 p.m.

    It makes the scientist not believe that there was life on Earth before there was enough water to sustain life. "The common thinking of early volcanic Earth is that it was too molten. The belief has been that there was not enough liquid water for life to take hold this early. But, Harrison said, there's no physical evidence for this theory. What the zircon shows is "the Earth by 4.1, 4.2 billion years ago was basically behaving like it is today." I think it is interesting because know scientists have found out that there was life a lot earlier than they thought.

  • carlym-4-bar
    10/30/2015 - 12:34 a.m.

    The presence of water factor into scientists thinking about life on earth because everything that is alive, needs water to survive, so finding evidence of water that dates back about 4 million years ago is incredible. In the article it says, "The belief has been that there was not enough liquid water for life to take hold this early." This explains how the scientists use to think that there wasn't enough water to support life, but because of new research, they are finding out that there was more water.
    I found this article very interesting because I never knew that there could be a possibility that there was life on earth 4 million years ago. 4 million years is very large compared to how long humans have been on earth.

  • peterk-lam
    11/02/2015 - 02:27 p.m.

    Something in this article I found interesting was the fact that we don't know exactly how life on Earth started.

  • alexh6-sch
    11/03/2015 - 08:57 a.m.

    How can scientists find what the earth looks like if they only have fossils of life from 4 billion years ago.

  • andrewb-wes
    11/04/2015 - 12:23 p.m.

    Scientist think that with out water there won't be any life on earth because organism need water to survive without water plant will die animals will die everything on planet earth will die.

  • kyleighp-fel
    11/09/2015 - 02:15 p.m.

    The presence of water factors into scientist thinking about life on earth because water is essential to all life.

  • mimir-fel
    11/09/2015 - 02:18 p.m.

    The presence of water make scientist believe that there was life since water is mandatory for any life form.

  • travisb-fel
    11/09/2015 - 02:19 p.m.

    The presence of water makes scientists think early volcanic earth might not have been as different as it is today.

  • mattv-fel
    11/09/2015 - 02:19 p.m.

    The presence of water factors into scientists thinking about life on earth because the first ever creatures to exist on earth were those who lived in the ocean.

  • kolbyd-fel
    11/09/2015 - 02:19 p.m.

    The presence of water factor is that it didn't have enough liquid water for life to take hold.

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