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PhDemon
Post  Post subject: How Life Started  |  Posted: Thu Nov 03, 2016 1:31 pm

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A good overview of current thinking on how life on Earth started:

http://www.bbc.com/earth/story/20161026 ... arth-began

Maybe I'm biased, John Sutherland who is quoted quite extensively was my organic chemistry tutor when I was an undergrad ;)

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Thu Nov 03, 2016 5:01 pm
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Very cool PH. A lot of scrolling at this end but worth the read. Some of the early stuff I've seen before but what I can't get over is the knowledge level of chemistry one must possess in order to conduct first life experiments. For some reason I liked the part about clay and membranes. Does it mean life is more likely to form if a planet has a volcanic environment?

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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Thu Nov 03, 2016 5:55 pm
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imo what we need for life as we know it is : (1) water at the triple point, i.e. liquid, gaseous and solid (2) a magnetic field so not too much water dissociates in the upper atmosphere; and (3) plate tectonics which keeps the volcanic resurfacing going at a regular pace (and which probably needs sufficient liquid water to form oceans)

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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Thu Nov 03, 2016 6:42 pm

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Zinjanthropos wrote:
Does it mean life is more likely to form if a planet has a volcanic environment?


I don't know about "more likely" with a sample of one making probability calls is tricky! There is certainly intriguing research indicating that's how it happened here though.

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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Thu Nov 03, 2016 7:31 pm
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black smokers and lower temperature variants of them have the advantage of rock porosity(i.e. lots of surface area where reactions can take place), high concentrations of sulphur and hydrogen-rich molecules and high temperatures (but with part of the environment at temperatures not too high for organic chemistry to do interesting things)

the point is, smokers are a consequence of volcanic activity under water, which is what sea floor spreading as a result of plate tectonics will give you

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Fri Nov 04, 2016 11:20 am
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I don't know how but I get the feeling that if one needs something to kick start life then they're going to have to go deeper, into the quantum world and all its weirdness..

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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Fri Nov 04, 2016 11:52 am

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Everything at the scale of atoms is ultimately quantum mechanical... it ain't that weird ;)

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Fri Nov 04, 2016 4:41 pm
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Could there have been other factors in Life's origins that no longer exist on Earth, or there's a lack of evidence for? I'm thinking we may never find the spark here but somewhere out in the vastness of space it's plentifully obvious.

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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Fri Nov 04, 2016 7:15 pm
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the one condition that no longer exists on earth is that it's no loner free of life
hence the chemicals that, given sufficient time might have evolved into self-replicating units, get eaten / used by living organisms to build replenish their own chemistry

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Sat Nov 05, 2016 3:36 pm
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marnixR wrote:
the one condition that no longer exists on earth is that it's no loner free of life
hence the chemicals that, given sufficient time might have evolved into self-replicating units, get eaten / used by living organisms to build replenish their own chemistry


Sad to think that the first living organism might have been devoured by some evolving young upstart. :cry:

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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Thu Dec 08, 2016 11:50 pm

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marnixR wrote:
imo what we need for life as we know it is : (1) water at the triple point, i.e. liquid, gaseous and solid (2) a magnetic field so not too much water dissociates in the upper atmosphere; and (3) plate tectonics which keeps the volcanic resurfacing going at a regular pace (and which probably needs sufficient liquid water to form oceans)


In addition to a planet with a strong enough magnetic field to protect it's water vapor and atmosphere from solar wind from it's star I think you also need a star with a strong enough magnetic field to protect it's planet from the strong interstellar solar winds that could possibly compromise the planet's magnetic field, if left by itself.


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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Fri Dec 09, 2016 4:40 pm
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I had surmised that all F and G type stars would fit the bill, or have I got that wrong ?

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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Fri Dec 09, 2016 10:52 pm

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marnixR wrote:
I had surmised that all F and G type stars would fit the bill, or have I got that wrong ?


Our Sun is a G-type star and has about 0.8 to 1.2 solar masses and has a surface temperature of about 5300 to 6000 K.

A F-type star has about 1.0 to 1.4 solar masses and a surface temperature of about 6000 to 7600 K.

The two types of stars are roughly similar in solar masses and surface temperature so I would say there is a good chance that if a planet is about the same distance away from its star as the Earth is away from the Sun, and has a similar mass and size to the Earth, a strong enough magnetic field to protect it from its stars solar wind, and the other necessary ingredients for life, such as H2O and CO2, then I think it can be a possible candidate for supporting some level of life.


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Lynx_Fox
Post  Post subject: Re: How Life Started  |  Posted: Mon Dec 12, 2016 5:13 pm

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marnixR wrote:
black smokers and lower temperature variants of them have the advantage of rock porosity(i.e. lots of surface area where reactions can take place), high concentrations of sulphur and hydrogen-rich molecules and high temperatures (but with part of the environment at temperatures not too high for organic chemistry to do interesting things)

the point is, smokers are a consequence of volcanic activity under water, which is what sea floor spreading as a result of plate tectonics will give you



Think they also have the advantage, that much of the conditions we still think of for the Goldilocks' zone, and discussion of solar size etc. would be far less applicable because they are deep and protected from CMEs, interstellar, and other destructive EM effects on the surface.


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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Mon Dec 12, 2016 6:19 pm
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indeed - you need energy to form the long chains that will ultimately become RNA, DNA and enzymes, but we also know that high energy radiation such as UV will break these chains up before they can achieve anything useful

the volcanic heat resolves this dilemma, and the cover of miles of water protects against damaging radiation

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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Mon Dec 19, 2016 3:12 pm

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I life on Earth had development full or in part underwater around black smokers and other lower temperature variants than maybe life could exist in other places where there is liquid water and volcanic activity. The planet or moon would still need to be the right distance from its star to have liquid water on the surface, unless the planet or moon was still hot enough in its development to have liquid water.


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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Sat Jan 14, 2017 2:39 pm

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I recently read about the possibility of methane-based organisms in a very cold water-less and oxygen-less environment living on Saturn's moon Titan. Temperatures on Titan can reach -290 degrees Fahrenheit but if you think that such temperatures are still too cold for methane-based life to exist I also read that there are methane spewing volcanos on Titan where it is probably a lot warmer and more habitable for life.


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Lynx_Fox
Post  Post subject: Re: How Life Started  |  Posted: Sun Jan 15, 2017 7:03 am

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mmatt9876 wrote:
I life on Earth had development full or in part underwater around black smokers and other lower temperature variants than maybe life could exist in other places where there is liquid water and volcanic activity. The planet or moon would still need to be the right distance from its star to have liquid water on the surface, unless the planet or moon was still hot enough in its development to have liquid water.


Or in a stable orbit around a large planet. Several of the moons around our gas planets have sufficient tidal friction to keep liquid water beneath the surface.


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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Sun Jan 15, 2017 3:31 pm

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Lynx_Fox wrote:
mmatt9876 wrote:
I life on Earth had development full or in part underwater around black smokers and other lower temperature variants than maybe life could exist in other places where there is liquid water and volcanic activity. The planet or moon would still need to be the right distance from its star to have liquid water on the surface, unless the planet or moon was still hot enough in its development to have liquid water.


Or in a stable orbit around a large planet. Several of the moons around our gas planets have sufficient tidal friction to keep liquid water beneath the surface.


Good point Lynx_Fox. Jupiter bends and flexes it's moon Europa as it orbits around the planet generating interior heat which may allow for liquid water beneath Europa's icy surface. Europa also has underwater volcanoes where bacteria may thrive like bacteria can thrive on Earth.


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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Fri Mar 03, 2017 2:47 pm

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Just spotted this news article:

http://www.bbc.co.uk/news/science-environment-39117523

They claim they have found evidence of life very early in Earth's history, although others disagree and say it is uncertain that they are of biological origin...
Interesting stuff anyway.

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 5:35 pm
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PhDemon wrote:
Just spotted this news article:

http://www.bbc.co.uk/news/science-environment-39117523

They claim they have found evidence of life very early in Earth's history, although others disagree and say it is uncertain that they are of biological origin...
Interesting stuff anyway.


Maybe I'm reading this wrong but why would first life forms have a biological origin?

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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 5:46 pm

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What I meant was the "fossils" they have found may not have been produced by life. If that is the case the authors' claim of finding the earliest known life form is dodgy, it might just be chemical weathering of minerals.

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Zinjanthropos
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 6:07 pm
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PhDemon wrote:
What I meant was the "fossils" they have found may not have been produced by life. If that is the case the authors' claim of finding the earliest known life form is dodgy, it might just be chemical weathering of minerals.


That's what I figured but thanks for clarifying. I wonder what they could look for in the rocks that might indicate the transition from inanimate to animate or is that asking too much?

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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 6:15 pm

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I think it could be tricky, as the article shows what some see as a biologically produced signature can often be explained by non-biological processes... Finding unambiguous "biological" material could be difficult as it tends not to last billions of years like rocks do...

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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 7:55 pm
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PhDemon wrote:
What I meant was the "fossils" they have found may not have been produced by life. If that is the case the authors' claim of finding the earliest known life form is dodgy, it might just be chemical weathering of minerals.


indeed - after all, what is biology but chemistry with ideas above its station ?

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PhDemon
Post  Post subject: Re: How Life Started  |  Posted: Mon Mar 06, 2017 9:20 pm

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I keep telling the biology teachers at work that... They throw things at me :lol:

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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Tue Mar 07, 2017 3:29 pm

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It is interesting that the approximately 3.77 billion year old rocks formed around ancient hydrothermal vents found in an area of Quebec where there was once an ancient sea may have supported life around a time when Mars may have also supported it's own life around similar hydrothermal vents and rocks under it's oceans.


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paleoichneum
Post  Post subject: Re: How Life Started  |  Posted: Wed Mar 08, 2017 12:30 am
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mmatt9876 wrote:
It is interesting that the approximately 3.77 billion year old rocks formed around ancient hydrothermal vents found in an area of Quebec where there was once an ancient sea may have supported life around a time when Mars may have also supported it's own life around similar hydrothermal vents and rocks under it's oceans.

The problem with that group of rock is the microstructures are only "punitive" (per the papers authors) and many other geologists and paleontologists have noted the heavily altered nature of the rock. Its a dubious claim at this point.

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mmatt9876
Post  Post subject: Re: How Life Started  |  Posted: Wed Mar 08, 2017 2:31 pm

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paleoichneum wrote:
mmatt9876 wrote:
It is interesting that the approximately 3.77 billion year old rocks formed around ancient hydrothermal vents found in an area of Quebec where there was once an ancient sea may have supported life around a time when Mars may have also supported it's own life around similar hydrothermal vents and rocks under it's oceans.

The problem with that group of rock is the microstructures are only "punitive" (per the papers authors) and many other geologists and paleontologists have noted the heavily altered nature of the rock. Its a dubious claim at this point.


Understood. If there is only one group pushing the assertion that life could have existed 3.77 billion years ago in these rocks and other groups suggest the findings are highly questionable then I change my opinion on the matter.


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marnixR
Post  Post subject: Re: How Life Started  |  Posted: Wed Mar 15, 2017 7:42 am
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now here's an interesting one :

Metabolism may be older than life itself and start spontaneously

the Krebs cycle could well be older than life as we know it

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