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    Life Developed 3.6 Billion Years Ago - Then Evolution Got Stuck In Slime
    By News Staff | February 27th 2014 10:25 PM | 4 comments | Print | E-mail | Track Comments

    The first life developed in ancient oceans some 3.6 billion years ago, but then nothing much happened. For a billion years, we remained pretty much a layer of slime. 

    Then 550 million years ago, evolution came roaring back and here we are today. So what was the hold-up during a billion boring years?

    According to University of Tasmania geologist Professor Ross Large and colleagues, the key was a lack of oxygen and nutrient elements, which placed evolution in a precarious position. "During that billion years, oxygen levels declined and the oceans were losing the ingredients needed for life to develop into more complex organisms."

    By analyzing ancient seafloor rocks, the researchers are now able to show that the slowdown in evolution was tightly linked to low levels of oxygen and biologically-important elements in the oceans.




    The red line represents the estimated oxygenation curve based on the abundance of the trace element selenium (Se) in pyrite samples. Oxygen levels are presented as %PAL (Present Atmospheric Levels), where 100% PAL represents the Earth's atmospheric oxygen at the present day. Credit: University of Tasmania

    "We've looked at thousands of samples of the mineral pyrite in rocks that formed in the ancient oceans. And by measuring the levels of certain trace elements in the pyrite, using a technique developed in our labs, we've found that we can tell an accurate story about how much oxygen and nutrients were around billions of years ago."

    "We were initially looking at oxygen levels in the ancient oceans and atmosphere to understand how mineral deposits form, and where to look for them today. That's a focus of the Centre for Ore Deposit and Exploration Science (CODES), which we established with ARC and industry funding at UTAS in 1989," Ross explains. "But the technology we have developed to find minerals can also tell us much about the evolution of life."

    After an initial burst of oxygen, the study plots a long decline in oxygen levels during the 'boring billion' years before leaping up about 750-550 million years ago. "We think this recovery of oxygen levels led to a significant increase in trace metals in the ocean and triggered the 'Cambrian explosion of life'.

    "We will be doing much more with this technology, but it's already becoming clear that there have been many fluctuations in trace metal levels over the millennia and these may help us understand a host of events including the emergence of life, fish, plants and dinosaurs, mass extinctions, and the development of seafloor gold and other ore deposits," says Ross.



    Large and Maslennikov on the hunt for suitable black shales in Siberia. Credit: University of Tasmania


    Published in Earth and Planetary Science Letters.
    Source: Science in Public

    Comments

    Bad arithmetic ... or bad writing ... or both?
    From: http://www.science20.com/news_articles/life_developed_36_billion_years_a...

    ++++
    The first life developed in ancient oceans some 3.6 billion years ago, but then nothing much happened. For a billion years, we remained pretty much a layer of slime.

    Then 550 million years ago, evolution came roaring back and here we are today. So what was the hold-up during a billion boring years?
    +++++++

    So, now, 3.6 - 0.55 = 1 ?

    No by-line; maybe the author was too embarrassed to admit writing it?

    The body of the article is more enlightening. It shows a long period of fluctuation in oxygen levels (a by-product of bacterial metabolism) in the atmosphere (based on levels of oxidation of iron compounds in the rocks) from 3.6 to about 1.8 BYA; THEN a stasis (but at a significantly higher level than previously) from 1.8 to 0.8 BYA.

    At least 1.8 - 8 = 1, but then the text in the introduction is wildly inaccurate.

    Based on the figure, the ONLY billion-year--long periods of stasis (based on oxidation data displayed in the graph) is from 3.5-2.5 BYA ;the time from the first life to the "Great Oxidation Event". After that, there is no demonstrable break point in the tracing of the graph for another 2 billion years, despite the hiccup around 2BYA. So, there is no rationale for putting the blue arrow THERE.

    It is bad enough that most Americans cannot read a simple graph; please do not add to the confusion.

    Furthermore, the quotation: "During that billion years, oxygen levels declined and the oceans were losing the ingredients needed for life to develop into more complex organisms" does NOT appear in the original article that you are supposedly citing ... which makes one question if the author(s) actually read it or if the article is based only on a press release or other public announcement. So, where did the quote come from?

    Really; if one of my students in scientific writing had turned this paper in, it would have gotten the comment: "Take it home and do it over!"

    Hank
    It's a press release, just like it says, but regardless the math is not that difficult. Because evolution accelerated 550 million years ago and was really slow for a billion years does not need to equal 3.6 billion. Evolution was still happening. I think if one of your biology students couldn't infer something so simple you would encourage them to spend their time in the humanities buildings instead.

    Who not light a candle for science outreach rather than cursing the darkness of non-corporate science sites that actually do it? Scientific American is part of a billion dollar company and has paid employees so if they write poorly, okay, jump on them, but criticizing a press release or the blogs of researchers who are not paid to write seems like a waste of your skills.
    but regardless the math is not that difficult

    All the more reason why they shouldn't have screwed it up so badly.

    criticizing a press release or the blogs of researchers who are not paid to write seems like a waste of your skills.

    So, because they were not paid, we should support writing that promotes misinformation and confusion?

    Hank
    If they were wrong, it would be easy to correct, yet no one has shown it to be wrong. So far, it only seems to be confusing to two people. Granted, a press release here is not going to be widely read, they are primarily by people who want to know what studies are coming out, so it may be that everyone else was really smart and if it had 100,000 readers a lot more would be confused. But the graphic seems accurate enough.