Posted on 11/04/2005 5:00:06 AM PST by PatrickHenry
Minerals help molecules thought to have been essential for early life to form.
A team of US scientists may have found the 'primordial womb' in which the first life on Earth was incubated.
Lynda Williams and colleagues at Arizona State University in Tempe have discovered that certain types of clay mineral convert simple carbon-based molecules to complex ones in conditions mimicking those of hot, wet hydrothermal vents (mini-volcanoes on the sea bed). Such complex molecules would have been essential components of the first cell-like systems on Earth.
Having helped such delicate molecules to form, the clays can also protect them from getting broken down in the piping hot water issuing from the vents, the researchers report in the journal Geology [Williams L. B., et al. Geology, 33. 913 - 916 (2005).].
"It's very interesting that the clays preserve them," says James Ferris, a specialist on the chemical origins of life at Rensselaer Polytechnic Institute in Troy, New York. "It shows that this could be an environment where complex organic molecules can be formed."
Some like it hot
Hydrothermal vents are created when seawater that has seeped through cracks in the seafloor is heated by magma just below the surface. The water streams back out of the rock in a plume that can reach temperatures of around 400 °C.
Vents are a favourite candidate for the site where life first appeared. Their heat provides an energy source; the minerals provide nutrients; and the deep-sea setting would have protected primitive organisms from the destructive meteorite impacts that scoured the planet's surface early in its history.
But researchers have long wondered how, if early life did form in this environment, it escaped being boiled and fried by the harsh conditions.
The Arizona State team has shown that clay minerals commonly found at vents can encase organic molecules, keeping them intact.
Between the sheets
The group simulated the vent environment in the laboratory, immersing various types of clay in pressurized water at 300 °C for several weeks and looking at the fate of a simple organic compound, methanol, in this stew. They chose methanol because their earlier work had shown that the compound could be formed in a vent environment from simple gases such as carbon dioxide and hydrogen.
Clays generally consist of sheets made of aluminium, silicon and oxygen atoms, which are stacked on top of one another. In some of these materials, such as the clays saponite and montmorillonite, there is room for other atoms and molecules to slip between the layers.
Spouting soup
The researchers found that the methanol in their artificial vent system was converted to various large organic molecules over six weeks or so, so long as the clay's layers were spaced widely enough to hold the compounds.
"The clay provides a safe haven for the organic molecules, essentially like a 'primordial womb'," the team reports. Eventually, changes in the clay's mineral structure caused by heat, pressure and time may cause the sheets to close up and expel the molecules inside. But they think that some of these could spout out from the clay into less hostile environments than the hottest part of the vent, creating an organic soup in which life might arise.
These findings add weight to the idea that clays were the key to the origin of life. Previous research has shown that clays act as catalysts for the formation of polymer molecules such as the precursors of proteins and DNA. They can also encourage lipid molecules to arrange themselves into cell-like compartments called vesicles.
This looks like two stats in one. (The mammal-like reptiles aren't mammals yet.) Ten million years after the first dinosaurs is probably about 215 million years ago. That's probably about right for true mammals.
Yes, natural selection is purpose driven. Those mutations that succeed in helping individuals pass on their genes survive, those that hinder their ability to do same do not.
Capacity for mutation need not be random. Individual mutations may be. The "randomly chosen" mutation in each specific instance still follows the distribution of susceptability.
A uniform sample of two unequal regions will still have more points from the bigger region.
My point is that the term "random" does not imply a specific distribution.
Not a morphological goal no, but it does have a goal in the sense that natural selection selects for mutations that increase the "fitness" of individuals within an environment. Passing on genes is the "goal." I think your economic metaphor is apt here -- this selection is an invisible hand, and of course not an intelligence.
Fair enough. Likewise genetic drift isn't truly random.
Down goes Frazier.
Actually, redshifts had been observed a decade earlier, but no explanation for them had been proposed.
One is graduated bifocals so you can get dizzy looking down.
Makes climbing a bit more of a challenge.
But we do get to call people "sonny" or "girly" and get away with it.
Well, there's always "Old Farts"
Are you eligible?
If not, off to the kiddie table and watch your mouth, young'un.
Depends on the cut off. In either case, pretty damn close. My sons gave me a T-shirt "Older than Dirt". I wear it when I have an older but wiser point to prove.
It's getting worn out.
No, I don't think so, but he might be suggesting hyperbole is involved in the description. It might help to know what "complex" chemicals are involved. I seems certain that they are not above the level of the amino acids created by Miller-Urey otherwise it would be trumpeted to high heaven. Plus I can certify that complex "goo" can be achieved in minutes in the lab using very simple carbon compounds.
Biblical literalists (of every stripe) dislike Origen.
This is what I was saying. I expressed it backwards, something I am rather good at.
"Individual mutations may be. The "randomly chosen" mutation in each specific instance still follows the distribution of susceptability.
Gotcha. Any mutations that occur in areas of susceptability occur at a locus that is random.
"A uniform sample of two unequal regions will still have more points from the bigger region.
"My point is that the term "random" does not imply a specific distribution.
I think I have it.
And you are indeed an artist.
I just reached my 50th. Am I old enough to join or am I still wet behind the ears?
Maybe you can be a junior senior.
Have to submit it to the board.
It's the 2005 G3k Memorial Anti-Evo Unintended Irony Nominee.....
IF selected as this year's winner, the phrase "random selection" will take its place in the hallowed halls of ignominy already occupied by such stunning stupidities as:
1) 1720
2) "wildly elliptical" planetary orbits
3) "a circle is not an ellipse"
4) "infrared light causes sunburn"
to name but a few ....
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