Origin Of Life

Timeline for development of life squeezed even more?

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Dominic Papineau/credit Lee Pellegrini, Boston College

From “Young Graphite in Old Rocks Challenges the Earliest Signs of Life” (ScienceDaily, May 21, 2011) we learn:

The team — which includes researchers from Boston College, the Carnegie Institution of Washington, NASA’s Johnson Space Center and the Naval Research Laboratory — says new evidence from Canada’s Hudson Bay region shows carbonaceous particles are millions of years younger than the rock in which they’re found, pointing to the likelihood that the carbon was mixed in with the metamorphic rock later than the rock’s earliest formation — estimated to be 3.8 to 4.2 billion years ago.

That’s means

“The characteristics of the poorly crystalline graphite within the samples are not consistent with the metamorphic history of the rock,” said Boston College Assistant Professor of Earth and Environmental Sciences Dominic Papineau, a co-author of the report. “The carbon in the graphite is not as old as the rock. That can only ring a bell and require us to ask if we need to reconsider earlier studies.”Nearly 4,000-million years old samples from Greenland have been used to develop the dominant time line regarding the emergence of the earliest biosphere. The recent findings suggest the biosphere may have emerged millions of years later, a hypothesis that now demands a rigorous study, said Papineau.

Is there a backstop to the compression somewhere? Well, today is May 22, 2011 CE, 07:25 PM EST, and things can’t get much later than this, while still being in the past. Can they?

3 Replies to “Timeline for development of life squeezed even more?

  1. 1
    bornagain77 says:

    And yet the rock itself gives indication of photosynthetic activity:

    U-rich Archaean sea-floor sediments from Greenland – indications of >3700 Ma oxygenic photosynthesis
    Authors: Rosing, Minik T.; Frei, Robert
    Abstract: 3700 Ma metamorphosed pelagic shale from West Greenland contains up to 0.4 wt% reduced carbon with ?13C values down to -25.6‰ [PDB, PeeDee Belemnite]. The isotopic signature and mode of occurrence suggest that the carbon derived from planktonic organisms. The Pb isotopic composition shows that the shale had high primary U/Th. This indicates that organic debris produced a local reducing environment which precipitated U transported to the site of sedimentation by oxidized ocean water. The existence of highly productive plankton that fractionated C isotopes strongly and set up oxidation contrast in the environment suggests that oxygenic photosynthesis evolved before 3700 Ma.
    http://adsabs.harvard.edu/abs/2004E&PSL.217..237R

  2. 2
    bornagain77 says:

    a bit more background detail on bio-geochemical signatures is here;

    When Did Life First Appear on Earth? – Fazale Rana – December 2010
    Excerpt: The primary evidence for 3.8 billion-year-old life consists of carbonaceous deposits, such as graphite, found in rock formations in western Greenland. These deposits display an enrichment of the carbon-12 isotope. Other chemical signatures from these formations that have been interpreted as biological remnants include uranium/thorium fractionation and banded iron formations. Recently, a team from Australia argued that the dolomite in these formations also reflects biological activity, specifically that of sulfate-reducing bacteria.
    http://www.reasons.org/when-di.....pear-earth

  3. 3
    junkdnaforlife says:

    Possibly equally as troubling as the question of”when” is the question of “where”, and the rise and fall of a true icon: The Primordial Soup

    “Despite bioenergetic and thermodynamic failings the 80-year-old concept of primordial soup remains central to mainstream thinking on the origin of life,” said senior author, William Martin, an evolutionary biologist from the Insitute of Botany III in Düsseldorf. “But soup has no capacity for producing the energy vital for life.”

    http://www.sciencedaily.com/re.....101245.htm

    No soup for you!
    http://www.youtube.com/watch?v=kNwbjcuQUv8

    But there is a solution, sort of. Thermal vents. However…

    “Prebiotic chemistry points to a low-temperature origin because most biochemicals decompose rather rapidly at temperatures of 100 degrees C (e.g., half-lives are 73 min for ribose, 21 days for cytosine, and 204 days for adenine).

    http://www.ncbi.nlm.nih.gov/pubmed/11539558

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