[math-fun] How miraculous was the origin of life? Experiment suggested to answer this.
Meeker's cite led to this summary: http://www2.asa3.org/archive/evolution/199705/0014.html SELF-REPLICATION: Even peptides do it By Stuart A. Kauffman Nature 382 (8 Aug 1996). Do not be too excited -- this "lifeform" is a 32-amino polypeptide which catalyes its formation from 15- and 17-long halves, assumed already present in environment. But we could regard it as meeting Allan Wechsler's notion of "semi-life" and conceive that many interacting systems of this nature could suffice to synthesize themselves from an amino-soup. C.Greathouse claimed he felt it unlikely even a single mutation would leave a lifeform viable. Wrong. Actually, proteins do usually still work if 1 amino is altered. It helps to avoid aminos in the small "active site" and to keep the amino in the same "class" meaning {hydrophobic, hydrophilic} but the latter is usually not necessary if it is only one amino changing. Thinking a bit about really stripping down a bacterium, all we really need are the DNA, transcription machinery, ribosome, and a DNA polymerase, if we optimistically assume aminos and nucleotide triphosphates were available in environment. In all that'd be about 100 genes fitting in about 10000 base pairs. If we claim the "true complexity" of N-amino proteins is not 20^N or 64^N but rather more like 2^N in view of the 2-class approximate view, and if we claim the 100 genes could be permuted in 100! ways and it'd still work, then we get this number of bits: log( 2^3333 / 100! ) / log(2) = 2808 bits. (This also would be about the complexity of 100 interacting peptide systems of the ilk at top.) Which is still far above from the complexity the abiotic universe could be expected to provide by luck. Which is what? If the entire Earth surface 10 meters deep is regarded as a laboratory performing 1 experiment per cubic angstrom per millisecond for 10^9 years, then I get this number of experiments: 2^217. (If there were also 10^20 planet earths out there, then increase this to 2^283.) So to get genesis of life on Earth, we need to reduce the bit count 2808 by a factor of at least 13, but probably reducing it by a factor 25 would be good enough.
C.Greathouse claimed he felt it unlikely even a single mutation would leave a lifeform viable. Wrong. Actually, proteins do usually still work if 1 amino is altered.
No, you misunderstood me. A single mutation typically leaves an organism viable, but a single mutation of a *minimal* organism would generally render it nonviable. (Obviously, by definition, any point deletion renders them nonviable.) Think about old-school programmers writing machine code under extreme space limitations: portions of programs are reused, instructions 'fall through' into others, etc. Charles Greathouse Analyst/Programmer Case Western Reserve University On Fri, May 8, 2015 at 12:17 PM, Warren D Smith <warren.wds@gmail.com> wrote:
Meeker's cite led to this summary: http://www2.asa3.org/archive/evolution/199705/0014.html SELF-REPLICATION: Even peptides do it By Stuart A. Kauffman Nature 382 (8 Aug 1996).
Do not be too excited -- this "lifeform" is a 32-amino polypeptide which catalyes its formation from 15- and 17-long halves, assumed already present in environment.
But we could regard it as meeting Allan Wechsler's notion of "semi-life" and conceive that many interacting systems of this nature could suffice to synthesize themselves from an amino-soup.
C.Greathouse claimed he felt it unlikely even a single mutation would leave a lifeform viable. Wrong. Actually, proteins do usually still work if 1 amino is altered. It helps to avoid aminos in the small "active site" and to keep the amino in the same "class" meaning {hydrophobic, hydrophilic} but the latter is usually not necessary if it is only one amino changing.
Thinking a bit about really stripping down a bacterium, all we really need are the DNA, transcription machinery, ribosome, and a DNA polymerase, if we optimistically assume aminos and nucleotide triphosphates were available in environment. In all that'd be about 100 genes fitting in about 10000 base pairs. If we claim the "true complexity" of N-amino proteins is not 20^N or 64^N but rather more like 2^N in view of the 2-class approximate view, and if we claim the 100 genes could be permuted in 100! ways and it'd still work, then we get this number of bits: log( 2^3333 / 100! ) / log(2) = 2808 bits. (This also would be about the complexity of 100 interacting peptide systems of the ilk at top.)
Which is still far above from the complexity the abiotic universe could be expected to provide by luck. Which is what? If the entire Earth surface 10 meters deep is regarded as a laboratory performing 1 experiment per cubic angstrom per millisecond for 10^9 years, then I get this number of experiments: 2^217. (If there were also 10^20 planet earths out there, then increase this to 2^283.)
So to get genesis of life on Earth, we need to reduce the bit count 2808 by a factor of at least 13, but probably reducing it by a factor 25 would be good enough.
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It would seem highly unlikely for the first lifeform (if we can even define what that means) to be a "minimal" organism. It's very hard to make something minimal. Minimal organisms might evolve because of competition for limited resources, but the first organisms presumably didn't have that problem. While competition might favor minimality, changing environments would favor the opposite in order to provide the feedstock for adaptation. A reproducing organism that has perfectly adapted to its environment and minimized itself for that situation is likely to quickly disappear when the situation changes. But an organism with a lot of overhead won't be able to compete with the more optimized organism while the environment remains stable. So what is the "optimum" size? How does it depend on the pace of change of the environment? But the first lifeforms just had to barely "work". When did evolution take over from randomness? --ms On 08-May-15 14:48, Charles Greathouse wrote:
C.Greathouse claimed he felt it unlikely even a single mutation would leave a lifeform viable. Wrong. Actually, proteins do usually still work if 1 amino is altered.
No, you misunderstood me. A single mutation typically leaves an organism viable, but a single mutation of a *minimal* organism would generally render it nonviable. (Obviously, by definition, any point deletion renders them nonviable.) Think about old-school programmers writing machine code under extreme space limitations: portions of programs are reused, instructions 'fall through' into others, etc.
Charles Greathouse Analyst/Programmer Case Western Reserve University
On Fri, May 8, 2015 at 12:17 PM, Warren D Smith <warren.wds@gmail.com> wrote:
Meeker's cite led to this summary: http://www2.asa3.org/archive/evolution/199705/0014.html SELF-REPLICATION: Even peptides do it By Stuart A. Kauffman Nature 382 (8 Aug 1996).
Do not be too excited -- this "lifeform" is a 32-amino polypeptide which catalyes its formation from 15- and 17-long halves, assumed already present in environment.
But we could regard it as meeting Allan Wechsler's notion of "semi-life" and conceive that many interacting systems of this nature could suffice to synthesize themselves from an amino-soup.
C.Greathouse claimed he felt it unlikely even a single mutation would leave a lifeform viable. Wrong. Actually, proteins do usually still work if 1 amino is altered. It helps to avoid aminos in the small "active site" and to keep the amino in the same "class" meaning {hydrophobic, hydrophilic} but the latter is usually not necessary if it is only one amino changing.
Thinking a bit about really stripping down a bacterium, all we really need are the DNA, transcription machinery, ribosome, and a DNA polymerase, if we optimistically assume aminos and nucleotide triphosphates were available in environment. In all that'd be about 100 genes fitting in about 10000 base pairs. If we claim the "true complexity" of N-amino proteins is not 20^N or 64^N but rather more like 2^N in view of the 2-class approximate view, and if we claim the 100 genes could be permuted in 100! ways and it'd still work, then we get this number of bits: log( 2^3333 / 100! ) / log(2) = 2808 bits. (This also would be about the complexity of 100 interacting peptide systems of the ilk at top.)
Which is still far above from the complexity the abiotic universe could be expected to provide by luck. Which is what? If the entire Earth surface 10 meters deep is regarded as a laboratory performing 1 experiment per cubic angstrom per millisecond for 10^9 years, then I get this number of experiments: 2^217. (If there were also 10^20 planet earths out there, then increase this to 2^283.)
So to get genesis of life on Earth, we need to reduce the bit count 2808 by a factor of at least 13, but probably reducing it by a factor 25 would be good enough.
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participants (3)
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Charles Greathouse -
Mike Speciner -
Warren D Smith