Nyikos may be right about panspermia

[William Morse]

On NPR's science Friday today there was a discussion about the origin of
life. There is recent work on the chemistry for creating ribose that
indicates the conditions conducive to its production (the presence of
borax and molybdate) were more likely to have existed on Mars than on
Earth.

[Glenn]

"William Morse" <wdNOSP...@verizon.net> wrote in message news:l0dvi...@news6.newsguy.com...

http://www.bbc.co.uk/news/science-environment-23872765

[Mitchell Coffey]

Is the argument that there was not enough borax and molybate on Earth,
or just less than on Mars?

Mitchell Coffey

[John Harshman]

Big problem with that idea: how does life get from Mars to Earth? No
proposed mechanism would work. Ooh, except Peter's. If we find evidence
of a Martian technological civilization four billion years ago, I'm in.

[rnorman]

Lots of meteorites on Earth come from Mars. They could carry organic
chemicals.

[jillery]

On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
<jhar...@pacbell.net> wrote:

Martian meteorites.

[jillery]

<http://sciencefriday.com/playlist/#play/segment/9213>


IIUC they're saying the early Earth was too wet, ironically.

[John Harshman]

I thought it was life that was supposed to come from Mars, not just
borax. It doesn't seem to me that you would be able to get a significant
quantity of necessary chemicals from the few meteorites that would make
the trip.

[John Harshman]

Yes, that's one of the proposed mechanisms that wouldn't work.
Meteorites typically spend many millions of years in space while getting
from Mars to Earth. How many organisms are going to survive millions of
years in space? Or just millions of years, for that matter.

[Mitchell Coffey]

I thought the borax and molybate were just needed to get life started.

Mitchell

[Glenn]

"rnorman" <r_s_n...@comcast.net> wrote in message news:almarsoft.8114...@news.eternal-september.org...

"It's yet another piece of evidence which makes it more likely life came to Earth on a Martian meteorite, rather than starting on this planet."

""The evidence seems to be building that we are actually all Martians; that life started on Mars and came to Earth on a rock," he commented."

http://www.bbc.co.uk/news/science-environment-23872765

http://en.wikipedia.org/wiki/Steven_A._Benner

[jillery]

On Fri, 06 Sep 2013 19:32:53 -0700, John Harshman

IIUC they're discussing prebiotic molecules, without a need for
metabolism. Hearing it from them might help you:


<http://sciencefriday.com/playlist/#play/segment/9213>

[John Harshman]

Not following your line of thought here.

[John Harshman]

It isn't clear to me how 1) meteors could deliver significant amounts of
ribose to Earth or 2) how even ribose survives millions of years in space.

[jillery]

On Fri, 06 Sep 2013 23:39:27 -0400, jillery <69jp...@gmail.com>

Apparently a direct link doesn't work. Try this:

<http://sciencefriday.com/segment/09/06/2013/life-from-mars.html>

and click on "listen" with popups enabled.

The other point the speaker makes that I found very interesting is
that scientists have identified the discrete chemical steps necessary
to get from basic compounds like CO2 and N2 to self-replicating RNA.
What they have not done yet is to make a continuous synthesis. And he
didn't sound the least bit naive to me.

[alias Ernest Major]

The idea that living organisms could be transferred from Mars to Earth
by rocks ejected from Mars by collisions has been seriously considered
in the past.

What is necessary is that

1) rocks can be ejected by collisions without being sterilised (the
lower gravity and thinner atmosphere of Mars makes that easier).

2) living organisms can survive on/in those rocks until they intercept
the Earth.

3) living organisms can survive the entry of those rocks into the
Earth's atmosphere.

--
alias Ernest Major

[John Harshman]

I think the big problem is #2, as the mean travel time is in the tens of
millions of years.

[Richard Norman]

It has already been mentioned by jillery and suggested by me that it
could have been merely the prebiotic organic molecules that "seeded"
earth, not actual living things.

That is not exactly what is ordinarily thought of as panspermia and is
certainly not 'directed' but it does suggest a non-terrestrial
'origin' of abiogenesis.

[alias Ernest Major]

The typical travel time is millions of years. The minimum travel time
might be a little as a few years, depending on whether rocks can be
kicked off Mars with sufficient sunwards velocity to intersect the
Earth's orbit, or whether the orbit has to be altered by a close
approach to Mars or another body first.

It doesn't matter how proportionately small the low duration tail
(perhaps up to tens of thousands of years) is, provided only that it is
large enough to accomodate local panspermia.

--
alias Ernest Major

[Robert Carnegie]

It was mentioned in the news recently that there are modern microbes
inside rock underground whose life process is extraordinarily slow.
Here: <http://www.bbc.co.uk/news/science-environment-23855436>

[Glenn]

"Robert Carnegie" <rja.ca...@excite.com> wrote in message news:3f029a33-a0f1-445a...@googlegroups.com...

That's nothing. Take this:
http://news.bbc.co.uk/2/hi/science/nature/978774.stm

[John Harshman]

I see a big problem here. If it's actual organisms making the trip,
they'd be unlikely to survive. If it's organic molecules, there would
not be likely to be enough, in the right place, to assist in
abiogenesis. Even assuming they survived the trip.

[John Harshman]

I find it hard to believe that the low duration tail is big enough to
include even one such object. Given that Mars is about the same age as
earth, there isn't all that much time for the required events to accumulate.

[John Harshman]

Not really relevant, since any life would have to be completely dormant
to have any tiny hope of survival.

[Mark Isaak]

Life gets started on Mars. Some of it crawls into a hole in a rock.
Huge meteor hits Mars, kicks the rock into space. Many years pass
until, at last, the rock hits Earth, landing in a warm little pond. The
life wakes up, crawls out of its hole, and sets on on a campaign of
world domination.

--
Mark Isaak eciton (at) curioustaxonomy (dot) net
"It is certain, from experience, that the smallest grain of natural
honesty and benevolence has more effect on men's conduct, than the most
pompous views suggested by theological theories and systems." - D. Hume

[jillery]

The first self-reproducing molecule might have needed minimal
conditions for its preservation. Once created, it only needed to be
kept out of direct sunlight, cosmic rays, and extreme heat, until such
time that it would find itself in an environment where it could
reproduce itself.

Complex organic molecules are known to exist in space. Organic
molecules have been recovered from the interiors of meteorites. So
the rigors of being blasted off Mars, traveling indefinitely through
space, and surviving a fiery re-entry onto Earth, is plausible.

[John Harshman]

Which brings us back to my original objection: that isn't going to
happen, since it requires the life to survive millions of years in space.

[Mark Isaak]

On 9/7/13 8:09 AM, John Harshman wrote:
> On 9/7/13 6:42 AM, Richard Norman wrote:
>> On Sat, 07 Sep 2013 06:33:58 -0700, John Harshman
>> <jhar...@pacbell.net> wrote:
>>
>>> On 9/7/13 12:53 AM, alias Ernest Major wrote:
>>>> On 07/09/2013 03:05, John Harshman wrote:

>>>>> [...]

>>>> The idea that living organisms could be transferred from Mars to Earth
>>>> by rocks ejected from Mars by collisions has been seriously considered
>>>> in the past.
>>>>
>>>> What is necessary is that
>>>>
>>>> 1) rocks can be ejected by collisions without being sterilised (the
>>>> lower gravity and thinner atmosphere of Mars makes that easier).
>>>>
>>>> 2) living organisms can survive on/in those rocks until they intercept
>>>> the Earth.
>>>>
>>>> 3) living organisms can survive the entry of those rocks into the
>>>> Earth's atmosphere.
>>>>
>>> I think the big problem is #2, as the mean travel time is in the tens of
>>> millions of years.
>>
>> It has already been mentioned by jillery and suggested by me that it
>> could have been merely the prebiotic organic molecules that "seeded"
>> earth, not actual living things.
>>
>> That is not exactly what is ordinarily thought of as panspermia and is
>> certainly not 'directed' but it does suggest a non-terrestrial
>> 'origin' of abiogenesis.
>>
> I see a big problem here. If it's actual organisms making the trip,
> they'd be unlikely to survive. If it's organic molecules, there would
> not be likely to be enough, in the right place, to assist in
> abiogenesis. Even assuming they survived the trip.

Adaptations to dessication allow many terrestrial species to remain
dormant for long periods of time, with their metabolism not merely
slowed but stopped altogether. That, in theory, would let them pass
millions of years in space, if sufficiently sheltered from radiation.
And it's no big stretch of the imagination to suppose that some life on
Mars, were it to exist, would adapt to dessication.

[Mitchell Coffey]

My understanding was that the theory behind this story was that borax
and molybate were needed in the appropriate quantities to obtain
abiogenesis, but once life existed, lower ambient quantities of those
minerals were necessary to maintain life.

Note that I personally don't believe borax and molybate are actual
limits on Earthly abiogenesis, as both may be concentrated by natural
means. Also, my understanding is that both would show up as dissolved in
water at higher concentrations than in the planet as a whole.

Mitchell Coffey

[Mitchell Coffey]

To play devil's advocate, I'll point out that "mean" isn't the relevant
summary statistic.

Mitchell Coffey

[Richard Norman]

On Sat, 07 Sep 2013 08:09:44 -0700, John Harshman

I see a lot of big problems. But, outlandish as it may be, it was
worth presenting at a meeting and getting press attention. The
presentation was the keynote talk by S. Benner at the session "Origins
of Life: Environments, Mineral Surfaces, and Prebiotic Chemistry" at
the 2013 Goldschmidt conference of the Geochemical Society and the
European Association of Geochemistry.
http://goldschmidt.info/2013/program/programViewThemes#period02g

The abstract is
http://goldschmidt.info/2013/abstracts/finalPDFs/686.pdf

[Paul J Gans]

Yes. All this is interesting stuff, but until we come up with
some reasonable mechanisms for abiogenesis, it all remains
problematic.

--
--- Paul J. Gans

[Dana Tweedy]

Maybe they were carried by interplanetary swallows.

DJT

--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Paul J Gans]

There are mechanisms for the "rapid" delivery of martian rocks to
earth. The major requirements are the placements of the planets
in their orbits at the time of impact creating the martian meteors.

I don't know if the postulated chemistry involved the delivery of
"large" amounts of material to the earth or just small "templates".

The problem is that I get the astrophysics but I don't grok the
biochemistry.

[Paul J Gans]

Are you saying that Microsoft is a direct descendent?

[Mitchell Coffey]

And, the story would go, not so much pixie dust (i.e, borax and
molybate) are needed to keep it alive on Earth as was necessary to get
it alive on Mars.

Mitchell Coffey

[Richard Norman]

People who think that life has no purpose do not understand what you
have just realized. It was a cleverly concealed plot from the very
beginning.

[Mitchell Coffey]

This may involve assuming more new entities than would the possibility
that life arose in a warm earthly puddle where borax and molybate had
been rather concentrated by natural processes.

Mitchell

[Richard Norman]

One serious problem as described in the presentatin is that the
molybdate had to be highly oxidized, something very unlikely in the
early earth chemistry but not in the Martian.

[Mitchell Coffey]

I'll say it. African or European interplanetary swallows?

Mitchell Coffey

[Earle Jones]

In article <xdidneJk-ol...@giganews.com>,

John Harshman <jhar...@pacbell.net> wrote:

> On 9/6/13 7:35 PM, Mitchell Coffey wrote:

> > On 9/6/2013 10:27 PM, John Harshman wrote:

> >> On 9/6/13 7:14 PM, rnorman wrote:
> >>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
> >>> <jhar...@pacbell.net> wrote:
> >>>> On 9/6/13 7:49 PM, William Morse wrote:
> >>>> > On NPR's science Friday today there was a discussion about the
> >>> origin of
> >>>> > life. There is recent work on the chemistry for creating ribose
> >>> that
> >>>> > indicates the conditions conducive to its production (the
> >>> presence of
> >>>> > borax and molybdate) were more likely to have existed on Mars
> >>> than on
> >>>> > Earth.
> >>>> >
> >>>> Big problem with that idea: how does life get from Mars to Earth?
> >>> No
> >>>> proposed mechanism would work. Ooh, except Peter's. If we find
> >>> evidence
> >>>> of a Martian technological civilization four billion years ago, I'm
> >>> in.
> >>>

> >>> Lots of meteorites on Earth come from Mars. They could carry organic
> >>> chemicals.
> >>>
> >> I thought it was life that was supposed to come from Mars, not just
> >> borax. It doesn't seem to me that you would be able to get a significant
> >> quantity of necessary chemicals from the few meteorites that would make
> >> the trip.
> >
> > I thought the borax and molybate were just needed to get life started.
>
> Not following your line of thought here.

*
John: The line of thought presented in the NPR "Science Friday" show
was this:

There are some planets that could produce the necessary biological
precursor chemicals, for example, borates and molybdates. Mars is a
good choice, owing to its low amount of water.

The earth would not be good at producing these chemicals, because it was
way too wet. The concentration of soluble salts would never reach the
necessary threshold for continued development toward a biomolecule.

On the other hand, planets that could support continued biological
development have a completely different profile. The Earth is a good
example of such a planet; Mars is not.

What this idea points out is this: it may require a pair of planets in
close (?) proximity to produce the type of life we know.

And Martian meteorites, kilograms per year, are found on earth.

To me, a plausible set of ideas.

earle
*

[Earle Jones]

In article
<1575963212400266956.653...@freenews.netfront.net>,

*
Not sure about boron and molybdenum, but I have heard of the barium
swallow.

earle
*

[jillery]

On Sat, 07 Sep 2013 13:47:28 -0400, Mitchell Coffey
<mitchel...@gmail.com> wrote:

Yeppers. I am a dedicated homegrown abiogeneticist. Only if
abiogenesis chemistry is so distinctive as to make it practically
impossible on early Earth, should alternatives be considered as more
likely. I argue not enough is know about either abiogenesis chemistry
or early Earth geology to assert that impossibility with any
reasonable foundation.

The audio makes the point that the argument is a negative one, that it
assumes the borax/molybdate chemistry is the correct one, and assumes
the timing/geology of homegrown abiogenesis makes Earth a Waterworld.
The jury on those assumptions haven't even been selected, nevermind
verdicts reached.

[Dana Tweedy]

African interplanetary swallows are non migratory.

[jillery]

There's one less thing to worry about *-)

[Paul J Gans]

Have people yet recognized that money, in high enough
concentration, self-replicates?

[John Harshman]

I don't see the relevance of that understanding to what we're talking about.

[Paul J Gans]

If I may add to that, many of these meteorites are not at
all ancient as meteorites go. And it is likely that the
early solar system, chaotic as it was, saw many more
martian meteorites than we'd find today.

[Richard Norman]

On Sat, 7 Sep 2013 23:01:28 +0000 (UTC), Paul J Gans

It works by a sort of cooperative binding effect, highly non-linear
with a rather high threshold for activation. I think the Hill
coefficient is around 6 or 7. It fully explains the fantastic growth
in wealth of the 0.1 percenters.

[John Harshman]

Is that claiming that life arose on Mars and was transferred to earth,
that organic chemicals arose on mars and were transferred to earth, or
that molybdates and borates arose on Mars and were transferred to earth?
In the latter two cases, I don't see how the quantities transferred
could make a difference. In the first case, I don't see how life could
possibly survive the trip.

> To me, a plausible set of ideas.

Not to me.

[John Harshman]

I doubt it. Millions of years are much longer than the times over which
dormant species have been known to survive. And that isn't in a vacuum,
which creates its own difficulties to which nothing is adapted.

> And it's no big stretch of the imagination to suppose that some life on
> Mars, were it to exist, would adapt to dessication.

Agreed, but that doesn't help enough.

[Paul J Gans]

Isn't that X-rayted?

[John Harshman]

Agreed. The question is how many rocks arrive after a sufficiently short
interval, which I would think would be measured in a few centuries, at
most. Given the numbers arriving per year and any reasonable
distribution of travel times, I would think that "none" might be a good
answer.

[Walter Bushell]

In article <l0gb88$gqq$1...@reader1.panix.com>,

As I have previously stated, the French "Cherchez la femme" translates
in American to "Follow the Money.".

--
Gambling with Other People's Money is the meth of the fiscal industry.
me -- in the spirit of Karl and Groucho Marx

[Mark Isaak]

A Chez Watt nomination to chew on:

>>>>> Big problem with that idea: how does life get from Mars to Earth? [...]

>>>>
>>>> Martian meteorites.
>>>>
>>> Yes, that's one of the proposed mechanisms that wouldn't work. Meteorites
>>> typically spend many millions of years in space while getting from Mars
>>> to Earth. How many organisms are going to survive millions of years in
>>> space? Or just millions of years, for that matter.
>>
>> Maybe they were carried by interplanetary swallows.
>>

> Not sure about boron and molybdenum, but I have heard of the barium
> swallow.

--
Mark Isaak eciton (at) curioustaxonomy (dot) net
"It is certain, from experience, that the smallest grain of natural
honesty and benevolence has more effect on men's conduct, than the most
pompous views suggested by theological theories and systems." - D. Hume

[Darwin123]

On Friday, September 6, 2013 10:32:53 PM UTC-4, John Harshman wrote:
> On 9/6/13 7:24 PM, jillery wrote:
>
> > On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
>

> > <jhar...@pacbell.net> wrote:
>
> >
>
> >> On 9/6/13 7:49 PM, William Morse wrote:
>
> >>> On NPR's science Friday today there was a discussion about the origin of
>
> >>> life. There is recent work on the chemistry for creating ribose that
>
> >>> indicates the conditions conducive to its production (the presence of
>
> >>> borax and molybdate) were more likely to have existed on Mars than on
>
> >>> Earth.
>
> >>>
>
> >> Big problem with that idea: how does life get from Mars to Earth? No
>
> >> proposed mechanism would work. Ooh, except Peter's. If we find evidence
>
> >> of a Martian technological civilization four billion years ago, I'm in.
>
> >
>
> >
>

> > Martian meteorites.
>
> >
>
> Yes, that's one of the proposed mechanisms that wouldn't work.
>
> Meteorites typically spend many millions of years in space while getting
>
> from Mars to Earth. How many organisms are going to survive millions of
>
> years in space? Or just millions of years, for that matter.

Bacterial endospores can germinate after millions of years. A bacterial
endospore is a dormant stage of a some Gram positive species. Bacterial
endospores don't need water, air or food. They can survive heating to
temperatures well above the boiling point of water. Vacuum wouldn't affect
them.

Bacterial endospores can be killed by many forms of radiation. They
be killed by UV radiation, gamma rays and cosmic rays.

By cosmic rays, I mean high energy nucleons. Most cosmic rays are in the form of high energy protons. Some "cosmic rays" come from solar wind. The magnetic field of planets accelerates solar wind to high velocities. These types of cosmic rays exist only near a planet. However, the cosmic rays with the largest energy are interstellar. They are accelerated by the magnetic field of the galaxy. Interstellar cosmic rays permeate the entire solar system.

The interstellar cosmic rays are the most unavoidable threat on a million year journey through space. UV radiation comes from the sun. However, it doesn't take much to block UV radiation. An endospore a few microns beneath the surface of a rock is protected from UV radiation. Solar wind cosmic rays are only significant close to a planet. However, interstellar cosmic rays have a high penetrating power and permeate the solar system. Interstellar cosmic rays would bombard a meteor for millions of years.

I don't know of any calculation performed. However, I conjecture that interstellar cosmic rays would sterilize any meteor that came from Mars to earth. I conjecture that an endospore could not survive the trip unless the meteor took a very direct route. If the meteor took only a few months to get to earth,and if there was a very high concentration of endospores on the meteor, then I could believe that a few endospores would survive.

The main source of gamma rays would be from the impact of cosmic rays on the rock in the meteroid. Gamma ray bursts would be too few and far between to matter. Hence, it comes down to interstellar cosmic rays. The constant bombardment of interstellar cosmic rays would eventually kill any endospore in the rock.

The problems of that bacterium have not ended once it gets to earth. Water it would have plenty of. If the newly germinated bacterium was a heterotroph, then the newly germinated endospore would have to find something to eat. If
it was an autotroph, it would need access to whatever energy source it used to synthesize its molecules.


Okay, here is a scenario. On Mars, there used to be a bacterium that both performed photosynthesis while vegetative state and became an endospore under harsh conditions. There was a whole mess of those things resting in mud. An astroid strike blew this mud into outer space. The pressure instantly made shale. The bacteria formed endospores in the middle of the shale. By coincidence, the rock took a direct route to earth in only a few months. Once the rock landed in the ocean, it eroded. The endospores germinated. Some surviving bacteria started to photosynthesize and reproduce. Their descendents are post messages on newsgroups even now.

Hey, it works for me !-)

[Ray Martinez]

On Friday, September 6, 2013 6:33:24 PM UTC-7, William Morse wrote:
> Nyikos may be right about panspermia

How many choices does the Atheist have? No matter how you slice it, Peter must accept abiogenesis like his Atheist colleagues, Crick & Orgel.

Ray

[....]

[Paul J Gans]

Yup. I'm starting to think that biology is important.

[Paul J Gans]

I'm not crass enough to suggest that these are really the same
thing. But I've always followed the women who've gone in the
opposite direction.

Comes from having taken vows of poverty when young.

[Paul J Gans]

Mark Isaak <eci...@curioustax.onomy.net> wrote:
>A Chez Watt nomination to chew on:

>>>>>> Big problem with that idea: how does life get from Mars to Earth? [...]
>>>>>
>>>>> Martian meteorites.
>>>>>
>>>> Yes, that's one of the proposed mechanisms that wouldn't work. Meteorites
>>>> typically spend many millions of years in space while getting from Mars
>>>> to Earth. How many organisms are going to survive millions of years in
>>>> space? Or just millions of years, for that matter.
>>>
>>> Maybe they were carried by interplanetary swallows.
>>>
>> Not sure about boron and molybdenum, but I have heard of the barium
>> swallow.

I'll second that!

[William Morse]

On 09/06/2013 10:27 PM, John Harshman wrote:
> On 9/6/13 7:14 PM, rnorman wrote:
>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
>> <jhar...@pacbell.net> wrote:
>>> On 9/6/13 7:49 PM, William Morse wrote:
>>> > On NPR's science Friday today there was a discussion about the
>> origin of
>>> > life. There is recent work on the chemistry for creating ribose
>> that
>>> > indicates the conditions conducive to its production (the
>> presence of
>>> > borax and molybdate) were more likely to have existed on Mars
>> than on
>>> > Earth.
>>> >

>>> Big problem with that idea: how does life get from Mars to Earth?

>> No
>>> proposed mechanism would work. Ooh, except Peter's. If we find
>> evidence
>>> of a Martian technological civilization four billion years ago, I'm
>> in.
>>
>> Lots of meteorites on Earth come from Mars. They could carry organic
>> chemicals.
>>
> I thought it was life that was supposed to come from Mars, not just
> borax. It doesn't seem to me that you would be able to get a significant
> quantity of necessary chemicals from the few meteorites that would make
> the trip.
>

Per the article, about a kilogram of Mars comes to earth every day from
meteorites.

[Paul J Gans]

A martian meteorite would face all of UV radiation, gamma rays
and cosmic rays. But it could happen.

[John Harshman]

On 9/7/13 5:46 PM, Darwin123 wrote:
> On Friday, September 6, 2013 10:32:53 PM UTC-4, John Harshman wrote:
>> On 9/6/13 7:24 PM, jillery wrote:
>>
>>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
>>
>>> <jhar...@pacbell.net> wrote:
>>
>>>
>>
>>>> On 9/6/13 7:49 PM, William Morse wrote:
>>
>>>>> On NPR's science Friday today there was a discussion about the origin of
>>
>>>>> life. There is recent work on the chemistry for creating ribose that
>>
>>>>> indicates the conditions conducive to its production (the presence of
>>
>>>>> borax and molybdate) were more likely to have existed on Mars than on
>>
>>>>> Earth.
>>
>>>>>
>>
>>>> Big problem with that idea: how does life get from Mars to Earth? No
>>
>>>> proposed mechanism would work. Ooh, except Peter's. If we find evidence
>>
>>>> of a Martian technological civilization four billion years ago, I'm in.
>>
>>>
>>
>>>
>>
>>> Martian meteorites.
>>
>>>
>>
>> Yes, that's one of the proposed mechanisms that wouldn't work.
>>
>> Meteorites typically spend many millions of years in space while getting
>>
>> from Mars to Earth. How many organisms are going to survive millions of
>>
>> years in space? Or just millions of years, for that matter.
>
> Bacterial endospores can germinate after millions of years.

I know of no claimed case of this happening that has actually been
verified. Do you?

> A bacterial
> endospore is a dormant stage of a some Gram positive species. Bacterial
> endospores don't need water, air or food. They can survive heating to
> temperatures well above the boiling point of water. Vacuum wouldn't affect
> them.
>
> Bacterial endospores can be killed by many forms of radiation. They
> be killed by UV radiation, gamma rays and cosmic rays.
>
> By cosmic rays, I mean high energy nucleons. Most cosmic rays are in the form of high energy protons. Some "cosmic rays" come from solar wind. The magnetic field of planets accelerates solar wind to high velocities. These types of cosmic rays exist only near a planet. However, the cosmic rays with the largest energy are interstellar. They are accelerated by the magnetic field of the galaxy. Interstellar cosmic rays permeate the entire solar system.
>
> The interstellar cosmic rays are the most unavoidable threat on a million year journey through space. UV radiation comes from the sun. However, it doesn't take much to block UV radiation. An endospore a few microns beneath the surface of a rock is protected from UV radiation. Solar wind cosmic rays are only significant close to a planet. However, interstellar cosmic rays have a high penetrating power and permeate the solar system. Interstellar cosmic rays would bombard a meteor for millions of years.
>
> I don't know of any calculation performed. However, I conjecture that interstellar cosmic rays would sterilize any meteor that came from Mars to earth. I conjecture that an endospore could not survive the trip unless the meteor took a very direct route. If the meteor took only a few months to get to earth,and if there was a very high concentration of endospores on the meteor, then I could believe that a few endospores would survive.
>
> The main source of gamma rays would be from the impact of cosmic rays on the rock in the meteroid. Gamma ray bursts would be too few and far between to matter. Hence, it comes down to interstellar cosmic rays. The constant bombardment of interstellar cosmic rays would eventually kill any endospore in the rock.
>
> The problems of that bacterium have not ended once it gets to earth. Water it would have plenty of. If the newly germinated bacterium was a heterotroph, then the newly germinated endospore would have to find something to eat. If
> it was an autotroph, it would need access to whatever energy source it used to synthesize its molecules.
>
>
> Okay, here is a scenario. On Mars, there used to be a bacterium that both performed photosynthesis while vegetative state and became an endospore under harsh conditions. There was a whole mess of those things resting in mud. An astroid strike blew this mud into outer space. The pressure instantly made shale. The bacteria formed endospores in the middle of the shale. By coincidence, the rock took a direct route to earth in only a few months. Once the rock landed in the ocean, it eroded. The endospores germinated. Some surviving bacteria started to photosynthesize and reproduce. Their descendents are post messages on newsgroups even now.
>
> Hey, it works for me !-)

Thanks for the wink.

[William Morse]

On 09/07/2013 12:24 PM, Mitchell Coffey wrote:

> On 9/7/2013 12:04 AM, John Harshman wrote:
>> On 9/6/13 7:35 PM, Mitchell Coffey wrote:

>>> On 9/6/2013 10:27 PM, John Harshman wrote:

>>>> On 9/6/13 7:14 PM, rnorman wrote:
>>>>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
>>>>> <jhar...@pacbell.net> wrote:
>>>>>> On 9/6/13 7:49 PM, William Morse wrote:
>>>>>> > On NPR's science Friday today there was a discussion about the
>>>>> origin of
>>>>>> > life. There is recent work on the chemistry for creating ribose
>>>>> that
>>>>>> > indicates the conditions conducive to its production (the
>>>>> presence of
>>>>>> > borax and molybdate) were more likely to have existed on Mars
>>>>> than on
>>>>>> > Earth.
>>>>>> >
>>>>>> Big problem with that idea: how does life get from Mars to Earth?
>>>>> No
>>>>>> proposed mechanism would work. Ooh, except Peter's. If we find
>>>>> evidence
>>>>>> of a Martian technological civilization four billion years ago, I'm
>>>>> in.
>>>>>

>>>>> Lots of meteorites on Earth come from Mars. They could carry organic
>>>>> chemicals.
>>>>>
>>>> I thought it was life that was supposed to come from Mars, not just
>>>> borax. It doesn't seem to me that you would be able to get a
>>>> significant
>>>> quantity of necessary chemicals from the few meteorites that would make
>>>> the trip.
>>>

>>> I thought the borax and molybate were just needed to get life started.
>>
>> Not following your line of thought here.
>

> My understanding was that the theory behind this story was that borax
> and molybate were needed in the appropriate quantities to obtain
> abiogenesis, but once life existed, lower ambient quantities of those
> minerals were necessary to maintain life.
>

> Note that I personally don't believe borax and molybate are actual
> limits on Earthly abiogenesis, as both may be concentrated by natural
> means. Also, my understanding is that both would show up as dissolved in
> water at higher concentrations than in the planet as a whole.
>

Well the question is whether you can get high concentrations of these on
early earth, given what we think we know about early geologic
conditions. The discussion on NPR stated that one of the implications
was to relook at what we think we know about conditions on early earth.

[William Morse]

The discussion dismissed the third case, since molybdates and borates
would have been diluted. In the first and second case,you are making a
statement without any data to support your opinion. I will give that the
credibility it deserves, i.e. zero.

The interesting point was whether the development of life requires
multiple planets -one to create life and one to evolve complexity.

[John Harshman]

Why is the second case different from the third?

As for the first, do you know of any examples of living organisms
surviving for several mission years, much less when subjected to vacuum
and radiation?

> The interesting point was whether the development of life requires
> multiple planets -one to create life and one to evolve complexity.

That would be interesting if you were able to deal with the problems of
dispersal.

[John Harshman]

Not much, when you compare that with the mass of the earth's surface.
And you should note that those kilograms left Mars millions of years ago.

[Dale]

On 09/06/2013 10:49 PM, William Morse wrote:
> On NPR's science Friday today there was a discussion about the origin of
> life. There is recent work on the chemistry for creating ribose that
> indicates the conditions conducive to its production (the presence of
> borax and molybdate) were more likely to have existed on Mars than on
> Earth.
>

it's probably more of a question of where and when as opposed to if

also introducing the possibility of directed panspermia

--
Dale

[jillery]

On Sat, 07 Sep 2013 16:10:24 -0700, John Harshman

IIUC you seem to think that any life-starting material ejected from
Mars is very unlikely to survive the trip through space to Earth. My
impression is you base your assumption on the characteristics of
existing living organisms.

But what if the Martian life-starting material was not fully alive,
simpler than a virus, possibly simpler than a prion, but still capable
of reproducing itself under the right conditions?

The Murchison meteorite contains a variety of compounds important to
life, including amino acids and nucleobases. So we know that some
complex compounds are capable of surviving the trip. A
self-duplicating RNA embedded in a lipid vesicle might fare as well.

[Steven L.]

On 9/7/2013 1:16 PM, Dana Tweedy wrote:

> John Harshman <jhar...@pacbell.net> wrote:

>> On 9/6/13 7:24 PM, jillery wrote:
>>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman
>>> <jhar...@pacbell.net> wrote:
>>>
>>>> On 9/6/13 7:49 PM, William Morse wrote:
>>>>> On NPR's science Friday today there was a discussion about the origin of
>>>>> life. There is recent work on the chemistry for creating ribose that
>>>>> indicates the conditions conducive to its production (the presence of
>>>>> borax and molybdate) were more likely to have existed on Mars than on
>>>>> Earth.
>>>>>
>>>> Big problem with that idea: how does life get from Mars to Earth? No
>>>> proposed mechanism would work. Ooh, except Peter's. If we find evidence
>>>> of a Martian technological civilization four billion years ago, I'm in.
>>>
>>>

>>> Martian meteorites.
>>>
>> Yes, that's one of the proposed mechanisms that wouldn't work. Meteorites
>> typically spend many millions of years in space while getting from Mars
>> to Earth. How many organisms are going to survive millions of years in
>> space? Or just millions of years, for that matter.
>

> Maybe they were carried by interplanetary swallows.

Given that we're talking about life,

it's more likely that the interplanetary stork brought that little
Martian bundle of joy to Earth.



--
Steven L.

[John Harshman]

This depends on what you mean by "life-starting material".

> My
> impression is you base your assumption on the characteristics of
> existing living organisms.
>
> But what if the Martian life-starting material was not fully alive,
> simpler than a virus, possibly simpler than a prion, but still capable
> of reproducing itself under the right conditions?
>
> The Murchison meteorite contains a variety of compounds important to
> life, including amino acids and nucleobases. So we know that some
> complex compounds are capable of surviving the trip. A
> self-duplicating RNA embedded in a lipid vesicle might fare as well.

I think that anything sufficiently complex to replicate itself has a
problem of survival for millions of years, especially in an environment
filled with highly energetic radiation, though spontaneous processes
alone ought to be enough to deactivate it.

[Darwin123]

On Saturday, September 7, 2013 9:48:03 PM UTC-4, Paul J Gans wrote:



> A martian meteorite would face all of UV radiation, gamma rays
>
> and cosmic rays. But it could happen.
>

> > Darwin123 wrote:

A few minutes of UV radiation from the sun would kill every bacterial
endospore in minutes. There is no unicellular organism that could survive
direct UV radiation for more than an hour. Cosmic rays would kill any
organism in a few years, unicellular or multicellular. I propose that
these are the only two forms of radiation important to the problem.

Lets assume that the nonsentient weak panspermia (NWP) hypothesis is correct. Life arose on some other world. A meteor blasted some nonsentient
organism into space, the resulting meteor orbited around the sun for
an indeterminate amount of time, the meteor landed on earth, organisms
in the meteor found something to eat, and their descendents evolved into
us.

Nonsentient here means no space ships or intelligent aliens. Weak means
that the organism really did evolve on Mars. Hoyle believed in panspermia.
However, he also believed in a Steady State universe. Hence, he didn't
have to concern himself with the ultimate origin of life. Life always was
and always will be, according to Hoyle. Since most scientists agree with
some version of the Big Bang Theory, Hoyles's version of the Steady
State Theory is out. A biogenesis occurred the first time on some planet.

Let us assume that the first living thing formed on Mars. I don't
believe that myself. However, this hypothesis doesn't ring my Insanity
Detector.

Let us discuss two forms of radiation: solar UV and interstellar
cosmic rays.

Some multicellular organisms are able to survive in direct UV
exposure. However, multicellular organisms probably couldn't survive the
shock and heat of being blasted out into space. Furthermore, multicellular
organisms eventually age. There is no dormant phase of any extant
multicellular organism that could survive more than a few thousand years.
A red wood tree could resist UV and live a thousand years, but it
probably would be destroyed by the shock of being propelled into space.

Hypothetically, the organism propelled into outer space was unicellular.
Some unicellular organisms have a dormant phase that can survive in a dry
environment for very long time periods. These include bacterial endospores,
bacterial halophiles, and dinoflagellete cysts. Vacuum is very dry. However,
I agree that organisms similar to these may be able to live millions of years
in a vacuum. Therefore,

Let us assume that the organism in the meteor had a dormant
phase somewhat like either a bacterial endospore, a dormant halophile,
or a dinoflagellate cyst. Let us not make any hypothesis about the
active phase of the microorganism. For instance, no authotrophic bacterium
forms an endospore. However, I find it plausible that an extinct form
of bacterium may have formed endospores and used photosynthesis. If
you don't like that, recall that dinoflagellates have some stages in
their life cycle where they practice photosynthesis. The meteor may have
contained something analogous to a dinoflagellate cyst.

So the life span of organisms does not invalidate NWP. Time by itself
does not invalidate NWP. Vacuum by itself does not invalidate NWP. Yes, there
are organisms that could "hold their breath" for 100 million years. However,
they would be dormant. An organism could not remain both bone dry and active.
Hence, they couldn't multiply while in the meteor. Any spore killed by a
cosmic ray would not be replaced while the meteor was in orbit.

The organisms still has to survive radiation over a very long time
span. The trip would most probably last millions of years. These organsims
would have to be in the shade to survive UV radiation even a few minutes.
So one has to figure out how the hypothetical spores get shielded from
UV. Cosmic rays would kill the spores more slowly because cosmic rays
have a lower flux.

UV rays are highly absorbed or reflected by almost all solid materials.
So it is easy to imagine some form of UV shield forming "accidentally".
Never the less, UV radiation is even more lethal to a unicellular organism
than cosmic rays. Therefore, the nature of this shielding has to be addressed
even before cosmic rays.

There is no natural shielding that would protect the spore from
cosmic rays. Organisms are protected on earth from cosmic rays by the atmosphere. However, our atmosphere is very thick. The spore would have
to be so deep in the meteor that the meteor material provides the same
level of protection. If the meteor were solid rock, then no organism
would be able to get that deep into the rock. If the meteor were porous,
then the shielding would probably not remain intact during during
ejection from Mars.

The only thing that I can think of is that maybe the trip did not
take millions of years. Maybe by "accident" the meteor was launched
on a direct route that took months. I don't think this is probable.
However, I haven't done any calculations. Maybe the probability of
such an event over the time span of a billion years is large. Maybe
the frequency of asteroid hits on Mars was much larger 4 billion
years ago than the frequency of asteroid hits today.

Just for the record, I think NWP is implausible. However, I haven't
rejected on a priori grounds. A little data or calculation could spin me
either way. Vague references to improbability and complexity won't convince
me either way.

Calculators, anyone?

[Darwin123]

On Sunday, September 8, 2013 9:18:40 AM UTC-4, John Harshman wrote:
> On 9/7/13 11:05 PM, jillery wrote:
>
> > On Sat, 07 Sep 2013 16:10:24 -0700, John Harshman

> > The Murchison meteorite contains a variety of compounds important to
>
> > life, including amino acids and nucleobases. So we know that some
>
> > complex compounds are capable of surviving the trip. A
>
> > self-duplicating RNA embedded in a lipid vesicle might fare as well.
>
>
>
> I think that anything sufficiently complex to replicate itself has a
>
> problem of survival for millions of years, especially in an environment
>
> filled with highly energetic radiation, though spontaneous processes
>
> alone ought to be enough to deactivate it.

Amino acids and nucleobases are not complex compounds. They are
very simple compounds. These compounds are relatively stable compared
to the complicated molecules found in even the simplest living thing.
Finding amino acids and nucleobases in a Mars meteor does not show that
complex organic molecules can make the trip.

Complex proteins are made from amino acids. Proteins are not stable.
Every time you boil and egg, you force the protein molecules to
polymerize. The amino acid residues are not greatly affected. Living things
are made with proteins, not individual amino acids.

DNA and RNA are made from nucleobases and ribose. However, nucleobases
and ribose is relatively simple compared to DNA and RNA. All the nucleobases
are more stable than DNA and RNA. DNA and RNA are rather unstable compared
to proteins. Martian meteorites do not contain DNA or RNA from outer space.
There is no evidence that any form of RNA or DNA could last in outer space.

Bacterial endospores stabilize proteins, DNA and RNA by embedding
them in a crystal matrix. Therefore, these complex molecules would not
spontaneously decay in this crystal matrix. Therefore, it seems to me
that bacterial endospores from extant bacteria are a good model for the
organism that relocated from Mars to earth. There are other spores that
may survive the trip, but I don't know any that are more robust than
bacterial endospores.

Bacterial endospores in amber have been revived after millions of
years. However, they are vulnerable to radiation. They could not survive
direct exposure to radiation in the region between Mars and earth.
Therefore, a hypothesis should to be presented on how a bacterial
endospore can be shielded against radiation in the NWP scenario.

Just a recommendation.

[Vincent Maycock]

On Sat, 7 Sep 2013 17:50:05 -0700 (PDT), Ray Martinez
<pyram...@yahoo.com> wrote:

>On Friday, September 6, 2013 6:33:24 PM UTC-7, William Morse wrote:
>> Nyikos may be right about panspermia
>
>How many choices does the Atheist have?

Lack of evidence for a deity is the origin of both atheism and the
scientific acceptance of abiogenesis. So one does not lead to
another; rather they share a common origin. Since you're a theist, I
would point out that your rejection of abiogenesis is based on
religious bias rather than ojbective evaluation of the evidence.

[Richard Norman]

I think people should differentiate between a serious proposal and an
aside which may have been tossed out in an oral presentation as an
idea to be explored. I can't tell what the situation might be because
the abstract of the presentation only has vague and minimal reference
to Mars aspect of abiogenesis. See "Planets, Minerals and Life's
Origin" by Steven A. Benner at
http://goldschmidt.info/2013/abstracts/finalPDFs/686.pdf

I also think people should make an enormous distinction between what
is presented at a scientific conference and the press releases that
get distributed afterwards which emphasize only the most flashy and
eye catching aspects. No doubt the original investigators may also be
complicit in the hype but what they say to the press is often rather
different from what they say in meetings or write in papers as "real"
science.

[Darwin123]

On Saturday, September 7, 2013 9:54:24 PM UTC-4, John Harshman wrote:

> I know of no claimed case of this happening that has actually been
>
> verified. Do you?

Yes. In fact, I read the original articles for my own
work on bacterial endospores. However, I do not have links
to the original articles.

Here are links to some second generation references.
Most of them refer to one study of endospores which were
25-40 MY old. Note that there have also been dormant
halophiles that have been revived from even earlier.
I read those articles, too.


http://en.wikipedia.org/wiki/Endospore
"Endospores enable bacteria to lie dormant
for extended periods, even centuries.
Revival of spores millions of years old
has been claimed."

http://pscantie.myweb.uga.edu/resistance.html
"In 1995, a group of scientists reported the recovery
of bacterial spores from the gut of an extinct bee
25 - 40 million years old. The bee was allegedly trapped
and preserved in amber. Samples of bee tissue incubated
in sterile culture yielded endospore forming bacteria."

http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/spore.html
"Viable endospores have reportedly been isolated from
the gi tract of a bee embedded in amber between 25
and 40 million years ago. Viable endospores of a
halophilic (salt-loving) bacteria have also reportedly
been isolated from fluid inclusions in salt crystals
dating back over 250 million years!"

http://www.nethelper.com/article/Bacterial#Endospores
"In this dormant state, these organisms may remain
viable for millions of years,[83][84] and endospores
even allow bacteria to survive exposure to the vacuum and
radiation in space.[85]"

I have read the original studies of ancient amber very deeply.
These appear to be complete studies. I am not so sure about
the ability of endospores to survive radiation.

The physical basis of endospore robustness is rather
well established. The large molecules in an endospore are
embedded in a dry matrix which is almost crystalline. The
large molecules do not have room to move. Hence, the chemical
reactions associated with large molecules are inhibited.


Endospores are extremely stable relative to other living things.
They can tolerate relatively high temperatures as well as long periods
of time. You could bake them or freeze them. They still germinate.

Nothing can survive long exposure to cosmic rays. There
isn't a single organism that wouldn't eventually succumb to high
exposures of cosmic rays. Intense UV radiation would also destroy
any unicellular organism in an even shorter time.

Prions are configurations of complex protein molecules.
The configurations need other prion molecules to reproduce
themselves. Hence, I really can't see how life can propagate
on prion molecules. The amino acid residues that proteins are
made of are far more stable than prion molecules.

Do you have any references to an living things that couldn't
be destroyed by long exposure to cosmic rays?

[Paul J Gans]

Well, that's the issue, isn't it? Without some reasonable knowlege
of that, we can't even speculate as to the mechanism of abiogenesis.

[jillery]

On Sun, 8 Sep 2013 09:15:54 -0700 (PDT), Darwin123
<drose...@yahoo.com> wrote:

>On Sunday, September 8, 2013 9:18:40 AM UTC-4, John Harshman wrote:
>> On 9/7/13 11:05 PM, jillery wrote:
>>
>> > On Sat, 07 Sep 2013 16:10:24 -0700, John Harshman
>
>> > The Murchison meteorite contains a variety of compounds important to
>>
>> > life, including amino acids and nucleobases. So we know that some
>>
>> > complex compounds are capable of surviving the trip. A
>>
>> > self-duplicating RNA embedded in a lipid vesicle might fare as well.
>>
>>
>>
>> I think that anything sufficiently complex to replicate itself has a
>>
>> problem of survival for millions of years, especially in an environment
>>
>> filled with highly energetic radiation, though spontaneous processes
>>
>> alone ought to be enough to deactivate it.
>
> Amino acids and nucleobases are not complex compounds. They are
>very simple compounds.

Complex and simple are relative terms. I agree amino acids and
nucleobases are simpler than their polymers, but they are more complex
than water.

I am impressed with the durability of bacterial endospores. However
your argument is based on the characteristics of essentially modern
organisms. Even your amber-trapped organisms are closer to modern
bacteria than they are to first life. I propose instead that if
first-life on Earth came from Mars, it came as an earlier form than
bacteria, but still capable of reproducing itself.

[jillery]

To add to your points above, and given that we still don't know what
first life on Earth actually looked like, people should differentiate
between discussing what is more likely and what is possible.

[Stephanus]

> Mitchell

Life is not defined in your world view.

[Mitchell Coffey]

How does your world view define your constant and consistent lying?

Mitchell Coffey

[Burkhard]

Nominated
It is an unusual topic, and I like the step-by-step,
analytical approach

[Darwin123]

On Sunday, September 8, 2013 3:54:45 PM UTC-4, jillery wrote:
> On Sun, 8 Sep 2013 09:15:54 -0700 (PDT), Darwin123
>

Maybe the life transported as a simple precursor to modern bacteria.
I don't know what this earlier form would be like. However, I think it
reasonable that to assume that it contained large molecules. Large molecules
are unstable with respect to radiation such as UV and cosmic rays.

I wouldn't expect the bacteria from that long ago to be structured
precisely like the Gram-positive bacteria seen today. When I say
"bacterial endospore", I am being very general. The most important thing
about bacterial endospores is that their large molecules are embedded in
a crystal-like matrix.

I don't see how large molecules could possibly survive the journey
in any other way. The molecules would have to be embedded in a solid,
because otherwise they would "wiggle" too much. Unless the molecules were
embedded in a solid matrix, spontaneous or thermal reactions would degrade
the molecules.

I really don't see how a wet cell could possibly a million year journey
in outer space even aside from radiation. Vacuum would desiccate the cell.
Extremes of heat and cold would induce all types of reactions.

The reactions would degrade the large molecules. Degradation
could include both decomposition and polymerization. So I can't see
how anything containing a liquid solution of large molecules could
possibly survive. Every extant organism relies to some extent on a
aqueous liquid solution of large molecules.

Maybe the living things were crystals! There are some theories of
abiogenesis which hypothesize that crystals of different types were the
original frame works for the first cells. So maybe a bunch of these crystals
were launched from Mars by the impact of a meteroid.

One problem is that it is not clear at what point these crystals
can be considered alive. So it is not clear whether it could truly be
called pangenesis.

So maybe what traveled was a crystal of molybdenum oxide, with a
vanadium impurities. There is a theory that such crystals were the
precursors of living cells. However, I don't know how stable these
molybdenum oxide crystals would be. They themselves are large molecules,
in a sense. I suspect cosmic rays would do a number on them.

[Richard Norman]

On Sun, 08 Sep 2013 15:59:50 -0400, jillery <69jp...@gmail.com>
wrote:

I agree. Still at this stage in our understanding of the geochemistry
of early earth it doesn't hurt to try to list the things that are
possible to separate them from what seems not possible at all. My
impression is that the oral presentation was really intended to list
some of the rather severe obstacles that do exist but perhaps are not
fully considered in the early earth's environment.

[jillery]

On Sun, 8 Sep 2013 08:50:16 -0700 (PDT), Darwin123
<drose...@yahoo.com> wrote:

> The only thing that I can think of is that maybe the trip did not
>take millions of years. Maybe by "accident" the meteor was launched
>on a direct route that took months. I don't think this is probable.
>However, I haven't done any calculations. Maybe the probability of
>such an event over the time span of a billion years is large. Maybe
>the frequency of asteroid hits on Mars was much larger 4 billion
>years ago than the frequency of asteroid hits today.

There is a limit to how many meteor impacts a planet can endure
without essentially melting its crust and killing off incipient life.
That sets an upper bound.

A lower bound is set by the probability of any particular large meteor
hitting Mars at just the right time and place to inject the debris
into an Earth-crossing orbit whose duration is within life's tolerance
to endure the rigors of space travel. So the whole dual-planet
Martian transplant hypothesis depends on a Goldilocks solution of not
too many and not too few meteors.

This raises a point in my mind that hasn't been mentioned before. IIUC
it's assumed that life on Earth began almost as soon as it could, this
is once surface condition were stable enough long enough to not
immediate destroy incipient life. IIUC it's also assumed that Earth
and Mars formed essentially at the same time, and so also experienced
a period of intense meteor bombardment.

All of the above suggests that if there was Martian abiogenesis, it
could not have happened much sooner than that presumed for Earthly
abiogenesis. And from that, it suggests that the process of
transporting life from Mars to Earth needs to be a reasonably probable
mechanism. And from that, it suggest that the timing window is too
narrow for Martian life to infect Earth using a low probability
mechanism like transplant by meteor.

OTOH it's *possible* it happened that way. If so, it was an unlikely
event that's unlikely to be repeated in too many other solar systems.

[jillery]

On Sun, 08 Sep 2013 17:18:01 -0400, Richard Norman
<r_s_n...@comcast.net> wrote:

[...]

>>To add to your points above, and given that we still don't know what
>>first life on Earth actually looked like, people should differentiate
>>between discussing what is more likely and what is possible.
>
>I agree. Still at this stage in our understanding of the geochemistry
>of early earth it doesn't hurt to try to list the things that are
>possible to separate them from what seems not possible at all. My
>impression is that the oral presentation was really intended to list
>some of the rather severe obstacles that do exist but perhaps are not
>fully considered in the early earth's environment.

Given what is known of early Earth geology, early Martian geology, and
abiogenesis, ISTM premature to exclude anything not explicitly ruled
out by physics.

[William Morse]

Because in the second case the organic chemicals would have time to
catalyze further reactions before being diluted.

> As for the first, do you know of any examples of living organisms
> surviving for several mission years, much less when subjected to vacuum
> and radiation?

Yes.

[chris thompson]

On Friday, September 6, 2013 10:05:30 PM UTC-4, John Harshman wrote:
> On 9/6/13 7:49 PM, William Morse wrote:
>
> > On NPR's science Friday today there was a discussion about the origin of
>
> > life. There is recent work on the chemistry for creating ribose that
>
> > indicates the conditions conducive to its production (the presence of
>
> > borax and molybdate) were more likely to have existed on Mars than on
>
> > Earth.
>
> >
>
> Big problem with that idea: how does life get from Mars to Earth? No
>
> proposed mechanism would work. Ooh, except Peter's. If we find evidence
>
> of a Martian technological civilization four billion years ago, I'm in.

On the twenty-mule team, of course.

Chris

[Mitchell Coffey]

On 9/7/2013 4:08 PM, John Harshman wrote:
> On 9/7/13 9:24 AM, Mitchell Coffey wrote:

>> On 9/7/2013 12:04 AM, John Harshman wrote:
>>> On 9/6/13 7:35 PM, Mitchell Coffey wrote:
>>>> On 9/6/2013 10:27 PM, John Harshman wrote:
>>>>> On 9/6/13 7:14 PM, rnorman wrote:
>>>>>> On Fri, 06 Sep 2013 19:05:30 -0700, John Harshman

>>>>>> <jhar...@pacbell.net> wrote:
>>>>>>> On 9/6/13 7:49 PM, William Morse wrote:
>>>>>>> > On NPR's science Friday today there was a discussion about the
>>>>>> origin of
>>>>>>> > life. There is recent work on the chemistry for creating ribose
>>>>>> that
>>>>>>> > indicates the conditions conducive to its production (the
>>>>>> presence of
>>>>>>> > borax and molybdate) were more likely to have existed on Mars
>>>>>> than on
>>>>>>> > Earth.
>>>>>>> >
>>>>>>> Big problem with that idea: how does life get from Mars to Earth?
>>>>>> No
>>>>>>> proposed mechanism would work. Ooh, except Peter's. If we find
>>>>>> evidence
>>>>>>> of a Martian technological civilization four billion years ago, I'm
>>>>>> in.
>>>>>>

>>>>>> Lots of meteorites on Earth come from Mars. They could carry organic
>>>>>> chemicals.
>>>>>>
>>>>> I thought it was life that was supposed to come from Mars, not just
>>>>> borax. It doesn't seem to me that you would be able to get a
>>>>> significant
>>>>> quantity of necessary chemicals from the few meteorites that would
>>>>> make
>>>>> the trip.
>>>>
>>>> I thought the borax and molybate were just needed to get life started.
>>>
>>> Not following your line of thought here.
>>

>> My understanding was that the theory behind this story was that borax
>> and molybate were needed in the appropriate quantities to obtain
>> abiogenesis, but once life existed, lower ambient quantities of those
>> minerals were necessary to maintain life.
>

> I don't see the relevance of that understanding to what we're talking
> about.

Never mind, then.

>> Note that I personally don't believe borax and molybate are actual
>> limits on Earthly abiogenesis, as both may be concentrated by natural
>> means. Also, my understanding is that both would show up as dissolved in
>> water at higher concentrations than in the planet as a whole.
>>

>> Mitchell Coffey
>>
>>
>

[Walter Bushell]

In article <l0gkqr$kt8$4...@reader1.panix.com>,
Paul J Gans <gan...@panix.com> wrote:

> Mark Isaak <eci...@curioustax.onomy.net> wrote:
> >A Chez Watt nomination to chew on:
>
> >>>>>> Big problem with that idea: how does life get from Mars to Earth? [...]

> >>>>>
> >>>>> Martian meteorites.
> >>>>>
> >>>> Yes, that's one of the proposed mechanisms that wouldn't work. Meteorites
> >>>> typically spend many millions of years in space while getting from Mars
> >>>> to Earth. How many organisms are going to survive millions of years in
> >>>> space? Or just millions of years, for that matter.
> >>>
> >>> Maybe they were carried by interplanetary swallows.
> >>>

> >> Not sure about boron and molybdenum, but I have heard of the barium
> >> swallow.
>
> I'll second that!

And then there is the bury'em enema, one dose can end you pain.

--
Gambling with Other People's Money is the meth of the fiscal industry.
me -- in the spirit of Karl and Groucho Marx

[John Harshman]

What? They're supposed to be catalysts?

>> As for the first, do you know of any examples of living organisms
>> surviving for several mission years, much less when subjected to vacuum
>> and radiation?
>
> Yes.

Now you're just being annoying for the hell of it.

[John Harshman]

I think that even under the most friendly scenario, straight from Mars
to Earth by the most direct route, the trip would take several years.
And I don't think there are organisms that would survive that long an
exposure to cosmic rays. There are organisms that can survive intense
radiation, but they do it by highly active repair, not the sort of thing
available to a dormant spore. There are also solar storms to consider.

[John Harshman]

That's just the one study, isn't it? I'm skeptical. And the Permian
halophile you're talking about is even less credible. Here: Graur, D.,
and T. Pupko. 2001. The Permian bacterium that isn't. Molecular Biology
and Evolution 18:1143-1146.

> The physical basis of endospore robustness is rather
> well established. The large molecules in an endospore are
> embedded in a dry matrix which is almost crystalline. The
> large molecules do not have room to move. Hence, the chemical
> reactions associated with large molecules are inhibited.
>
>
> Endospores are extremely stable relative to other living things.
> They can tolerate relatively high temperatures as well as long periods
> of time. You could bake them or freeze them. They still germinate.
>
> Nothing can survive long exposure to cosmic rays. There
> isn't a single organism that wouldn't eventually succumb to high
> exposures of cosmic rays. Intense UV radiation would also destroy
> any unicellular organism in an even shorter time.
>
> Prions are configurations of complex protein molecules.
> The configurations need other prion molecules to reproduce
> themselves. Hence, I really can't see how life can propagate
> on prion molecules. The amino acid residues that proteins are
> made of are far more stable than prion molecules.
>
> Do you have any references to an living things that couldn't
> be destroyed by long exposure to cosmic rays?

There are such organisms, but they do it by having very good,
high-energy DNA repair systems that obviously are not available in the
present case.

[Darwin123]

On Monday, September 9, 2013 12:45:06 AM UTC-4, John Harshman wrote:
> On 9/8/13 9:59 AM, Darwin123 wrote:

> > I have read the original studies of ancient amber very deeply.
>
> > These appear to be complete studies. I am not so sure about
>
> > the ability of endospores to survive radiation.
>
>
>
> That's just the one study, isn't it? I'm skeptical. And the Permian
>
> halophile you're talking about is even less credible. Here: Graur, D.,
>
> and T. Pupko. 2001. The Permian bacterium that isn't. Molecular Biology
>
> and Evolution 18:1143-1146.

I have serious doubts about the halophile article. There are big issues
with later contamination associated with recrystalization. There was a salty
spring with similar bacteria close to the salt crystals from when the
bacteria were revived. So maybe post-Cambrian bacteria contaminated the
crystal. The article claimed that the scientists checked for recrystallization. However, I don't fully understand the method by which they did that. So maybe there was a mistake. Further, the study was done well before DNA technology was available. They couldn't sequence the genome of the bacteria. However, I think their conclusions are plausible.

I have little doubt about the study with the amber. The bacterial
spores that were revived were parasites that could only live in bee
hosts. This is why they were chosen. Therefore, there is little chance
of later contamination.

Amber can't recrystallize. The rosin hardens by polymerization, which
is basically irreversible. Keeping bees out of the laboratory is fairly
easy. So it is probable that the scientists kept bees out of their laboratory
when they chipped open the amber. The scientists sequenced the DNA of the bacterium. They showed that the genome had some novel features, aside from
the fact it was a bee parasite. Hence, I have confidence that these spores
really came from 25-40 MYA.

[John Harshman]

On 9/9/13 6:57 AM, Darwin123 wrote:
> On Monday, September 9, 2013 12:45:06 AM UTC-4, John Harshman wrote:
>> On 9/8/13 9:59 AM, Darwin123 wrote:
>
>>> I have read the original studies of ancient amber very deeply.
>>
>>> These appear to be complete studies. I am not so sure about
>>
>>> the ability of endospores to survive radiation.
>>
>>
>>
>> That's just the one study, isn't it? I'm skeptical. And the Permian
>>
>> halophile you're talking about is even less credible. Here: Graur, D.,
>>
>> and T. Pupko. 2001. The Permian bacterium that isn't. Molecular Biology
>>
>> and Evolution 18:1143-1146.
>
> I have serious doubts about the halophile article. There are big issues
> with later contamination associated with recrystalization. There was a salty
> spring with similar bacteria close to the salt crystals from when the
> bacteria were revived. So maybe post-Cambrian bacteria contaminated the
> crystal. The article claimed that the scientists checked for recrystallization. However, I don't fully understand the method by which they did that. So maybe there was a mistake. Further, the study was done well before DNA technology was available. They couldn't sequence the genome of the bacteria. However, I think their conclusions are plausible.

Did you read Graur & Pupko?

> I have little doubt about the study with the amber. The bacterial
> spores that were revived were parasites that could only live in bee
> hosts. This is why they were chosen. Therefore, there is little chance
> of later contamination.
>
> Amber can't recrystallize. The rosin hardens by polymerization, which
> is basically irreversible. Keeping bees out of the laboratory is fairly
> easy. So it is probable that the scientists kept bees out of their laboratory
> when they chipped open the amber. The scientists sequenced the DNA of the bacterium. They showed that the genome had some novel features, aside from
> the fact it was a bee parasite. Hence, I have confidence that these spores
> really came from 25-40 MYA.

I would really like to see this replicated independently.

[Mark Isaak]

On 9/7/13 6:54 PM, John Harshman wrote:

> On 9/7/13 5:46 PM, Darwin123 wrote:
>>>
>>> Meteorites typically spend many millions of years in space while getting
>>> from Mars to Earth. How many organisms are going to survive millions of
>>> years in space? Or just millions of years, for that matter.
>>

>> Bacterial endospores can germinate after millions of years.

>
> I know of no claimed case of this happening that has actually been
> verified. Do you?

Revived after 250 million years in a salt deposit:
http://www.microbeworld.org/interesting-facts/microbial-record-holders/oldest-living-microbes
(I don't know the status of follow-up research.)

Half a million years in permafrost:
http://www.sciencedaily.com/releases/2007/08/070827174320.htm
(The article mentions "active and living DNA", not living bacteria. I
presume that means the bacteria were not cultured, but there is other
evidence that they were living.)

553 days in space:
http://www.popsci.com/technology/article/2010-08/bacteria-survive-553-day-exposure-exterior-iss

--
Mark Isaak eciton (at) curioustaxonomy (dot) net
"It is certain, from experience, that the smallest grain of natural
honesty and benevolence has more effect on men's conduct, than the most
pompous views suggested by theological theories and systems." - D. Hume

[Mark Isaak]

On 9/8/13 1:39 PM, Burkhard wrote:
> Nominated
> It is an unusual topic, and I like the step-by-step,
> analytical approach

Seconded.

[airbo...@gmail.com]

On Saturday, September 7, 2013 7:15:57 PM UTC-4, John Harshman wrote:
> On 9/7/13 9:39 AM, Mitchell Coffey wrote:
>
> > On 9/7/2013 9:33 AM, John Harshman wrote:
>
> >> On 9/7/13 12:53 AM, alias Ernest Major wrote:

>
> >>> On 07/09/2013 03:05, John Harshman wrote:
>
> >>>> On 9/6/13 7:49 PM, William Morse wrote:
>
> >>>>> On NPR's science Friday today there was a discussion about the
>
> >>>>> origin of
>
> >>>>> life. There is recent work on the chemistry for creating ribose that
>
> >>>>> indicates the conditions conducive to its production (the presence of
>
> >>>>> borax and molybdate) were more likely to have existed on Mars than on
>
> >>>>> Earth.
>
> >>>>>
>
> >>>> Big problem with that idea: how does life get from Mars to Earth? No
>
> >>>> proposed mechanism would work. Ooh, except Peter's. If we find evidence
>
> >>>> of a Martian technological civilization four billion years ago, I'm in.
>
> >>>>
>

> >>> The idea that living organisms could be transferred from Mars to Earth
>
> >>> by rocks ejected from Mars by collisions has been seriously considered
>
> >>> in the past.
>
> >>>
>
> >>> What is necessary is that
>
> >>>
>
> >>> 1) rocks can be ejected by collisions without being sterilised (the
>
> >>> lower gravity and thinner atmosphere of Mars makes that easier).
>
> >>>
>
> >>> 2) living organisms can survive on/in those rocks until they intercept
>
> >>> the Earth.
>
> >>>
>
> >>> 3) living organisms can survive the entry of those rocks into the
>
> >>> Earth's atmosphere.
>
> >>>
>
> >> I think the big problem is #2, as the mean travel time is in the tens of
>
> >> millions of years.
>
> >
>
> > To play devil's advocate, I'll point out that "mean" isn't the relevant
>
> > summary statistic.
>
>
>
> Agreed. The question is how many rocks arrive after a sufficiently short
>
> interval, which I would think would be measured in a few centuries, at
>
> most. Given the numbers arriving per year and any reasonable
>
> distribution of travel times, I would think that "none" might be a good
>
> answer.

I don't think it's quite as far-fetched as all that. I believe the current record for survival of a prokaryotic spore is on the order of 40 million years - in amber - in the gut of a bee. Of course, such an organism can't be the LCA because it is far too advanced down the prokaryote branch. However, far simpler life forms could persist in a dehydrated state within surface rocks - bacillus subtilis spores have been revived from deep inside surface granite rock (again, too fancy an organism but just to illustrate the principle). And, just to speculate further, the greatest survival trait for putative organisms on Mars as time went on and Mars dried out would be, in all likelihood, the ability to survive dehydration. Heck, even a wafer-thin slice of self replicating RNA (to mix my Monty Python metaphors) might be enough to get the ball rolling - no competition, after all.

[John Harshman]

On 9/9/13 7:49 AM, Mark Isaak wrote:
> On 9/7/13 6:54 PM, John Harshman wrote:
>> On 9/7/13 5:46 PM, Darwin123 wrote:
>>>>
>>>> Meteorites typically spend many millions of years in space while
>>>> getting
>>>> from Mars to Earth. How many organisms are going to survive millions of
>>>> years in space? Or just millions of years, for that matter.
>>>
>>> Bacterial endospores can germinate after millions of years.
>>
>> I know of no claimed case of this happening that has actually been
>> verified. Do you?
>
> Revived after 250 million years in a salt deposit:
> http://www.microbeworld.org/interesting-facts/microbial-record-holders/oldest-living-microbes

Graur, D., and T. Pupko. 2001. The Permian bacterium that isn't.
Molecular Biology and Evolution 18:1143-1146.

> (I don't know the status of follow-up research.)
>
> Half a million years in permafrost:
> http://www.sciencedaily.com/releases/2007/08/070827174320.htm
> (The article mentions "active and living DNA", not living bacteria. I
> presume that means the bacteria were not cultured, but there is other
> evidence that they were living.)

Here's the actual article:
http://www.pnas.org/content/104/36/14401.abstract?sid=3362b024-ac50-407c-8f67-dd454325beef

If you look at the abstract, it seems to argue against anything that
would be useful for panspermy:

Recent claims of cultivable ancient bacteria within sealed environments
highlight our limited understanding of the mechanisms behind long-term
cell survival. It remains unclear how dormancy, a favored explanation
for extended cellular persistence, can cope with spontaneous genomic
decay over geological timescales. There has been no direct evidence in
ancient microbes for the most likely mechanism, active DNA repair, or
for the metabolic activity necessary to sustain it. In this paper, we
couple PCR and enzymatic treatment of DNA with direct respiration
measurements to investigate long-term survival of bacteria sealed in
frozen conditions for up to one million years. Our results show evidence
of bacterial survival in samples up to half a million years in age,
making this the oldest independently authenticated DNA to date obtained
from viable cells. Additionally, we find strong evidence that this
long-term survival is closely tied to cellular metabolic activity and
DNA repair that over time proves to be superior to dormancy as a
mechanism in sustaining bacteria viability.

> 553 days in space:
> http://www.popsci.com/technology/article/2010-08/bacteria-survive-553-day-exposure-exterior-iss
>

I haven't been able to find the actual publication on which this is
based. I find it very hard to believe. Vacuum would require a dormant
condition to survive, but UV would require very active DNA repair, i.e.
mutually exclusive responses. This really needs confirmation.

[John Harshman]

I'm dubious about all such claims.

> Of course, such an organism can't be the LCA because it is far too
> advanced down the prokaryote branch. However, far simpler life forms
> could persist in a dehydrated state within surface rocks - bacillus
> subtilis spores have been revived from deep inside surface granite
> rock (again, too fancy an organism but just to illustrate the
> principle).

Can you provide a citation for that? What does "deep inside" mean? In a
big crack?

> And, just to speculate further, the greatest survival
> trait for putative organisms on Mars as time went on and Mars dried
> out would be, in all likelihood, the ability to survive dehydration.
> Heck, even a wafer-thin slice of self replicating RNA (to mix my
> Monty Python metaphors) might be enough to get the ball rolling - no
> competition, after all.

Assuming survival of millions of years of vacuum and radiation (huge
assumptions), what are the chances of finding a congenial environment?