The Origins of Life

Now, I want to point out right off the bat that the theory of evolution does not try to explain where life originated from. However, as life needs to exist to evolve, it is a crucial stepping stone to getting where we are today. Yet whether life arose spontaneously or was placed on earth, it still evolves. So, I hope to clear up some misconceptions and put out some of the leading hypotheses about where life originated from.

Many creationists say that Louis Pasteur proved that life cannot arise from non-life. Untrue. What Pasteur really showed was that life does not currently spontaneously appear in complex form from non-life in nature; he did not demonstrate the impossibility of life arising in simple form from non-life by way of a long and propitious series of chemical steps and selections. He did not, nor has anyone else, proven that life could not arise once, then evolve.

One of the most famous experiments in delving into the topic of the origin of life was done by Urey in 1953, where he used compounds that we believe to be found on earth before life arose – molecular hydrogen (H2), methane (CH4), ammonia (NH3) and water vapor (H2O) – and running them through a system of heat, electricity and cooling processes. After a few days, Urey checked the final makeup of the brew, and discovered 7 amino acids, the building blocks of proteins. Later experiments used a more realistic atmosphere, replacing methane with carbon monoxide or dioxide (CO or CO2), and ammonia with molecular nitrogen (N2) – with similar results.

Sidney Fox successfully synthesized coascervate “cells” (a coascervate is a mixture of colloids that can, like lipids in modern cells, form a layer that will enclose molecules, but which can allow monomers to pass across it). These will, under some conditions, divide as they “grow” to form new cells.

Almost every creationist with any knowledge into this matter will at some point pull out some seemingly overwhelming statistic from astronomer Fred Hoyle that the odds of forming DNA from chance are are 1040,000 to one. There are a few problems with this “it’s statistically impossible” concept that they throw at you:
1) They calculate the odds of creating a completely modern protein or prokaryotic cell. This is not consistent with any realistic idea on the origin of life. The earliest life in all these ideas would be much simpler than even the most basic prokaryote right now.
2) They assume that there are a fixed number of proteins, with fixed sequences, that are required for life.
3) The formation of biological polymers from monomers is subject to the laws of biochemistry, which makes it much less than random.
4) They calculate the probability of sequential trials, rather than simultaneous trials. Because it’s not just one little pocket of amino acids (or whatever building block you’re using) rearranging to form the protein (or whatever molecule you’re trying to make). It’s millions upon billions of organic molecules rearranging all over earth. On the early Earth it is likely that the ocean had a volume of 1 x 1024 liters. Given an amino acid concentration of 1 x 10-6 M (on the low end of the hypothesized values for density of the soup, see Chyba and Sagan 1992), then there are roughly 1 x 1050 potential starting chains, so that a fair number of efficient peptide ligases (about 1 x 1031) could be produced in a under a year, let alone a million years. The synthesis of primitive self-replicators could happen relatively rapidly, even given a probability of 1 chance in 4.29 x 1040.

You can go more in-depth in theories on the origins of life here, or check out this easy to read chart:

Image

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~ by kriskodisko on January 1, 2014.

2 Responses to “The Origins of Life”

  1. I got a little lost with the science math bit. But the graphic was good. And the point is clear, so I approve.

  2. I read an article the other day about the percentage of Americans who don’t believe in evolution. It was depressing, and the snarling comments of unbelievers afterwrds was even worse. Unfortunately, explaning the science of it to people like that, doesn’t do any good. They profess distrust ofscience,yet they seem to have no problem using all of the science-based wonders available to them: medicine, electronics, etc…

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