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physicsgg

Life Before Earth

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On this semilog plot, the complexity of organisms, as measured by the length of  functional non-redundant DNA per genome counted by nucleotide base pairs (bp), increases  linearly with time (Sharov, 2012). Time is counted backwards in billions of years before the  present (time 0). Modified from Figure 1 in (Sharov, 2006).

On this semilog plot, the complexity of organisms, as measured by the length of functional non-redundant DNA per genome counted by nucleotide base pairs (bp), increases linearly with time (Sharov, 2012). Time is counted backwards in billions of years before the present (time 0). Modified from Figure 1 in (Sharov, 2006).

Alexei A. Sharov, Richard Gordon
An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed.
Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide.
The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes.
Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago.
This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no intelligent life in our universe prior to the origin of Earth, thus Earth could not have been deliberately seeded with life by intelligent aliens; Earth was seeded by panspermia; experimental replication of the origin of life from scratch may have to emulate many cumulative rare events; and the Drake equation for guesstimating the number of civilizations in the universe is likely wrong, as intelligent life has just begun appearing in our universe.
Evolution of advanced organisms has accelerated via development of additional information-processing systems: epigenetic memory, primitive mind, multicellular brain, language, books, computers, and Internet. As a result the doubling time of complexity has reached ca. 20 years.
Finally, we discuss the issue of the predicted technological singularity and give a biosemiotics perspective on the increase of complexity.
Read more: http://arxiv.org/ftp/arxiv/papers/1304/1304.3381.pdf

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Written by physicsgg

April 16, 2013 at 4:42 pm

2 Responses

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  1. I should go read the paper, but the first thing which strikes me about the graph is that the process of biological reproduction is considerably slower than that of chemical reaction. Isn’t there going to be some point where it’s no longer appropriate to project backwards with a straight line on a semilog graph? Before the first prokaryote, wouldn’t there just be (to push an analogy possibly too far) a soup of RNA, proteins, amino acids and lipids bubbling away in a geological test tube?

    rw23

    April 17, 2013 at 10:06 pm

  2. […] Life Before Earth […]

    Where Are the Aliens?

    April 19, 2013 at 4:52 am


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