Evidence that comets could have seeded life on Earth
March 7, 2013
Comets like Halley’s can be a breeding ground for complex molecules such as dipeptides. Comets colliding with Earth could have delivered these molecules and seeded the growth of more complex proteins and sugars necessary for life. (Credit: NASA)
A new experiment simulating conditions in deep space reveals that the complex building blocks of life could have been created on icy interplanetary dust and then carried to Earth aboard a comet or possibly meteorites, jump-starting life.
Chemists from the University of California, Berkeley, and the University of Hawaii, Manoa, showed that conditions in space are capable of creating complex dipeptides — linked pairs of amino acids — that are essential building blocks shared by all living things.
These molecules then catalyzed the formation of proteins (polypeptides), enzymes, and even more complex molecules, such as sugars, that are necessary for life.
The discovery of complex molecules
In an ultra-high vacuum chamber chilled to 10 degrees above absolute zero (10 Kelvin), Seol Kim and Ralf Kaiser of the Hawaiian team simulated an icy snowball in space, including carbon dioxide, ammonia and various hydrocarbons such as methane, ethane and propane. When zapped with high-energy electrons to simulate the cosmic rays in space, the chemicals reacted to form complex, organic compounds, specifically dipeptides, essential to life.
At UC Berkeley, UC Berkeley chemists Richard Mathies and Amanda Stockton then analyzed the organic residues through the Mars Organic Analyzer, an instrument that Mathies designed for ultrasensitive detection and identification of small organic molecules in the solar system. The analysis revealed the presence of complex molecules — nine different amino acids and at least two dipeptides — capable of catalyzing biological evolution on earth.
While scientists have discovered basic organic molecules, such as amino acids, in numerous meteorites that have fallen to Earth, they have been unable to find the more complex molecular structures that are prerequisites for our planet’s biology. As a result, scientists have always assumed that the really complicated chemistry of life must have originated in Earth’s early oceans.
The paper was published online last week and is scheduled for the March 10 print issue of The Astrophysical Journal.
The research was supported by the National Science Foundation and the Mathies Royalty Fund at UC Berkeley.
In related news last week, researchers announced that they had discovered DNA and amino-acid precursor molecules molecules in interstellar space that may have formed on dusty ice grains floating between the stars.
Comments (8)
by CB
It seems that with the vastness of space, the propensity for so much creative matter and numerous planets capable of supporting life, the universe should be teeming with life. Yet we seem to be looking out across an empty ocean…
by RedQ_
DNA, not just precursors, quite clearly exists in space. See “Non-terrestrial origin of life: a transformative research paradigm shift” by N.C. Wickramasinghe published in January in Theory in Biosciences for a recent survey. Doesn’t have anything to do with comets.
by Vin
Perhaps complex molecules once produced cannot survive long enough in the harsh environment of space to explain why molecules only up to amino acids have been found in meteors unlike with this mimicking experiment. But if this is increasing the number of natural mechanisms that can kick start life, it’s all good I guess.
by SmartAndSober
I am thinking about non-carbon-based lifeforms, such as silicon-based.
As well, in a wider sense, “life” can mean any self-repairing, self-reproducing patterns.
by SmartAndSober
Biologist Lynn Margulis talked about Earth’s life came from “a system of microscopic cracks in the rocks”.
BTW, ” The maximum possible effectiveness of a software system increases in direct proportion to the log of the effectiveness (ie, speed, bandwidth, memory capacity) of the underlying hardware. ” – V. Vinge
Could very-fast-living lifeforms exist? (Nuclear lifeforms in a star, or in a neutron star)
by humanitarian
It is interesting to note a version of creation from India which states that microbes catching the underside of rocks surrounded by water and heavy rain for years started the process of life, against all odds. Where did this come from, obviously dust particles on ice from interstellar space, now being verified as a tangible evidence. The question is how did the microbe developed or had the audacity to survive in such fierce hostile environment.
by Vin
Natural selection and reproducing like crazy.
by Gorden Russell
Just take a course in Microbiology, humanitarian, and you will see that microbes have audacity all day long and far into the night.