Stanley Miller's classic "primordial soup" experimental setup,
with a simulated ocean, lightning and broth
of hydrogen, methane, ammonia and water.
Posted on 04/08/2005 7:39:14 AM PDT by PatrickHenry
A new University of Colorado at Boulder study indicates Earth in its infancy probably had substantial quantities of hydrogen in its atmosphere, a surprising finding that may alter the way many scientists think about how life began on the planet.
Published in the April 7 issue of Science Express, the online edition of Science Magazine, the study concludes traditional models estimating hydrogen escape from Earth's atmosphere several billions of years ago are flawed. The new study indicates up to 40 percent of the early atmosphere was hydrogen, implying a more favorable climate for the production of pre-biotic organic compounds like amino acids, and ultimately, life.
The paper was authored by doctoral student Feng Tian, Professor Owen Toon and Research Associate Alexander Pavlov of CU-Boulder's Laboratory for Atmospheric and Space Physics with Hans De Sterk of the University of Waterloo. The study was supported by the NASA Institute of Astrobiology and NASA's Exobiology Program.
"I didn't expect this result when we began the study," said Tian, a doctoral student in CU-Boulder's Astrobiology Center at LASP and chief author of the paper. "If Earth's atmosphere was hydrogen-rich as we have shown, organic compounds could easily have been produced."
Scientists believe Earth was formed about 4.6 billion years ago, and geologic evidence indicates life may have begun on Earth roughly a billion years later.
"This study indicates that the carbon dioxide-rich, hydrogen-poor Mars and Venus-like model of Earth's early atmosphere that scientists have been working with for the last 25 years is incorrect," said Toon. In such atmospheres, organic molecules are not produced by photochemical reactions or electrical discharges.
Toon said the premise that early Earth had a CO2-dominated atmosphere long after its formation has caused many scientists to look for clues to the origin of life in hydrothermal vents in the sea, fresh-water hot springs or those delivered to Earth from space via meteorites or dust.
The team concluded that even if the atmospheric CO2 concentrations were large, the hydrogen concentrations would have been larger. "In that case, the production of organic compounds with the help of electrical discharge or photochemical reactions may have been efficient," said Toon.
Amino acids that likely formed from organic materials in the hydrogen-rich environment may have accumulated in the oceans or in bays, lakes and swamps, enhancing potential birthplaces for life, the team reported.
The new study indicates the escape of hydrogen from Earth's early atmosphere was probably two orders of magnitude slower than scientists previously believed, said Tian. The lower escape rate is based in part on the new estimates for past temperatures in the highest reaches of Earth's atmosphere some 5,000 miles in altitude where it meets the space environment.
While previous calculations assumed Earth's temperature at the top of the atmosphere to be well over 1,500 degrees F several billion years ago, the new mathematical models show temperatures would have been twice as cool back then. The new calculations involve supersonic flows of gas escaping from Earth's upper atmosphere as a planetary wind, according to the study.
"There seems to have been a blind assumption for years that atmospheric hydrogen was escaping from Earth three or four billion years ago as efficiently as it is today," said Pavlov. "We show the escape was limited considerably back then by low temperatures in the upper atmosphere and the supply of energy from the sun."
Despite somewhat higher ultraviolet radiation levels from the sun in Earth's infancy, the escape rate of hydrogen would have remained low, Tian said. The escaping hydrogen would have been balanced by hydrogen being vented by Earth's volcanoes several billion years ago, making it a major component of the atmosphere.
In 1953, University of Chicago graduate student Stanley Miller sent an electrical current through a chamber containing methane, ammonia, hydrogen and water, yielding amino acids, considered to be the building blocks of life. "I think this study makes the experiments by Miller and others relevant again," Toon said. "In this new scenario, organics can be produced efficiently in the early atmosphere, leading us back to the organic-rich soup-in-the-ocean concept."
In the new CU-Boulder scenario, it is a hydrogen and CO2-dominated atmosphere that leads to the production of organic molecules, not the methane and ammonia atmosphere used in Miller's experiment, Toon said.
Tian and other team members said the research effort will continue. The duration of the hydrogen-rich atmosphere on early Earth still is unknown, they said.
I'm sorry, but the phrase "God is Truth" is insipid. Truth is a statement that accurately describes reality. So you're saying that God is a statement that accurately describes reality. But that's true exactly like "'JennyP exists' is a statement that accurately describes reality." So JennyP is Truth. So JennyP is God.
Now, if God does in fact exist, then it would be accurate to say "God truly exists" or something like that. But of course that's redundant, and it certainly can't be used as an a priori axiom upon which the very existence of Truth itself must depend.
I wonder ... if God spoke to us all, in clear unmistakable words, and announced that His work here was done, and He was leaving this universe forever in order to take care of business elsewhere, wouldn't we still be able to determine things like right, wrong, and truth?
You ask some very good questions. One I happen to know the answer to off the top of my head is, "Do plants and animals share a common ancestor?"
One of the oldest known animals are anenome's which voluntarily move to capture food. While these animals in many ways look and behave like plants, it is their voluntary motion which makes them animals. You would have to look even further back to find the shared ancestors of plants and anenomes.
Yep, as surely as we'd still be able to determine things like up vs. down, left vs. right, hot vs. cold.
"I'll remember that the next time I see ID'ers bashed for their lack of scientific proof, lol!"
I would agree with all of those edited statements.
It is quite true that God cannot be proven or disproven using todays scientific tools.
I don't know exactly why there are only two sexes instead of three or more. Sex is basically the exchange of genetic material which has the advantage of producing more diversity so two sexes are enough to accomplish this.
Did they evolve simultaneously?
Basically yes. However, that didn't happen all in one step. The first organisms that exchanged genetic material were hermaphrodites so they could be both, male and female. Only later some species became sexually "more specialized" by dropping the female function for one half of its population resp. the male function in the other half.
This is only a quick and dirty description but if you need more accurate information on this topic I'd recommend PatrickHenry's list-o-links. Maybe he can point you directly to a website where this is addressed in more detail.
"Why are there two sexes? Did they evolve simultaneously?"
'Claus Wilke of Caltech and Chris Adami, of both Caltech and JPL, have concluded that asexual bacteria can be nudged to evolve into sexual reproduction if they are subject to high levels of mutation induced by environmental stress—from, say, radiation exposure or a catastrophic meteor.'
http://66.102.7.104/search?q=cache:KvxxoPGDG1EJ:news.nationalgeographic.com/news/2001/07/0709_sexorigin.html+origins+of+sexual+reproduction&hl=en
It's called biased guessing. Unless they have a time machine, it's all just speculation.
Complete nonsense.
Once they come up with a proposed model (as they have here), based on what is already known (i.e. the laws of physics and chemistry, the age of the Earth, etc.), the model will then produce predictions which can be tested (for one example, about what chemical compounds should then be found in ancient rocks, and in what proportions as a result of such an early-Earth atmosphere, which can be tested by actually analyzing such rocks). This allows the hypothesis to be confirmed (if the tests match the predictions of the model) or falsified (if the tests fail to match the predictions of the model).
*That's* science. It is far more than "just speculation", and it does not require "a time machine" in order to test such ideas.
Please try to learn something about science before you attempt to critique it.
"Consciousness is an illusion; I'm really a machine that simulates consciousness"LOL, I never really understood how this is any different from simply stating that "I am conscious". If a machine can simulate consciousness then it is conscious. Sheesh.
Mind if I steal it? ;-)
And that reminds me of an old joke (but then what doesn't):
Oscar Wilde (a very prolific producer of witty sayings) once made yet another brilliant quip, and a friend of his said in admiration, "I wish I'd said that, Oscar". To which Wilde replied, "oh, I'm sure you will..."
Douglas "Wrong-Way" Corriganïs Curtiss Robin J-1 Special airplane, 1943.
Granddaughter yanks grandma's feeding tube
81-year-old neither terminally ill, comatose, nor in vegetative state
By Sarah Foster
© 2005 WorldNetDaily.com
In a situation recalling the recent death of Terri Schiavo in Florida, an 81-year-old widow, denied nourishment and fluids for nearly two weeks, is clinging to life in a hospice in LaGrange, Ga., while her immediate family fights desperately to save her life before she dies of starvation and dehydration.
Mae Magouirk was neither terminally ill, comatose nor in a "vegetative state," when Hospice-LaGrange accepted her as a patient about two weeks ago upon the request of her granddaughter, Beth Gaddy, 36, an elementary school teacher.
Also upon Gaddy's request and without prior legal authority, since March 28 Hospice-LaGrange has denied Magouirk normal nourishment or fluids via a feeding tube through her nose or fluids via an IV. She has been kept sedated with morphine and ativan, a powerful tranquillizer.
Her nephew, Ken Mullinax, told WorldNetDaily that although Magouirk is given morphine and ativan, she has not received any medication to keep her eyes lubricated during her forced dehydration.
"They haven't given her anything like that for two weeks," said Mullinax. "She can't produce tears."
10 - 9 - 8 - 7 - 6 - ....
Speculation, not supported by evidence. Another no-no.
Since it is the pathway used in even the simplest of cells as far back as we can ascertain, it is a conclusion warranted on the evidence.
That is not necessarily the case and indicates, as you have mentioned, that certain organics found in the complicated metabolic paths of even simple cellular organisms present today could not have existed during biogenesis. This is also a clear indication that whatever the first life forms were, they are not comparable to today's cellular life forms.
This is a circular argument: Abiogeneis didn't create cellular metaoblism because cellular metabolism cannot be formed by abiogenesis. You're caught in the circle because you are treating the premise as fact. That's a no-no.
Look it up. The research is being done. Knowing a bit of Chemistry myself, I can hazard a pretty safe bet that the molceular processes in thermal vent organisms will be even more complex than in more traditional forms; Heat can be a real problem for organic molecules, and there are likely control mechanisms in place to keep the critter from breaking down into simpler, non-living compounds.
The only problems I see with it were the ones I already listed when I wrote that as part of a larger post back in May of 2003.
If you have any issue with that post, feel free to reply to that post on that thread, instead of yanking a portion of it out of context and reposting it out of the blue on at least two entirely different threads now.
I've stolen enough of yours, so feel free.
"Conciseness does move particles. That's been "scientifically" proven."
You are looking, but you do not yet *see*. It is not the spoon that bends, that is impossible, rather you only need to realize that the spoon does not exist and it is you that must bend.
Sorry, couldn't' help myself :)
Prior to the observation, the particle exists as a field of probability that encompasses all possible locations for that particle. The act of observation causes that field to collapse and at that moment, the particle IS a particle once again, existing somewhere within that field, with some locations more likely that others.
The mind does not move the particles, rather that particles were neither here nor there until you observe them. It is not an issue of moving matter, but of forcing matter to make a decision on where the heck it is.
Well, that or there are infinite parallel universes, go figure.
I see three semi-independent questions here:
1. Why is sexual reproduction advantageous?
2. Why only *two* sexes?
3. How did the two sexes arise from non-sexual ancestors?
To address these, some common misconceptions need to be cleared up.
First, sexual reproduction does not actually require two or more sexes/genders. Sexual reproduction, fundamentally, is just the exchange of genetic material between two (or more) organisms. These organisms don't have to be "male" or "female" in any sense, and in fact many single-celled organisms (e.g. yeast) engage in sexual reproduction by fusing two separate cells, exchanging DNA, then separating.
The second misconception is that specialized male and female forms had to arise at exactly the same time (and *poof*, all at once). They didn't.
So to put it all together, the rise of sexual reproduction as we know it today in animals (and remember that many plants also engage in sexual reproduction, including male/female specialization) could easily have come about through progressive stages such as:
1. Unicellular organisms which reproduced asexually (i.e. by simple division), e.g. bacteria.
2. Unicellular organisms which gained the ability to fuse and exchange DNA in addition to division/budding, e.g. yeast.
3. Simple multicellular organisms (little more than communal colonies of unicellular organisms). Any single still would still have the ability to reproduce (and thus spin off a new colony) by either budding or two-celled sexual exchange. For example simple molds.
4. Simple but more advanced multicellular organisms, where different cells in the "colony" gain the ability to become more specialized based on location or chemical environment. Some regions would become specialized for ingestion of food, for example, while others would become more specialized at sexual reproduction (including specialized gametocyte cells, as well as simple "genitalia" or reproductive sites). Reproduction via single-celled division by any cell would become lost and the organism would now either entirely or primarily on on sexual reproduction (although the gametocytes would still in theory have the option of reproducing asexually). E.g. the higher fungi.
5. Full-blown specialized multicellular organisms as we know them, with specialized organs, etc., with a heavy dependence upon sexual reproduction via specialized organs, and a specialized differentiation between the "donor" and "receiver" cells involved in pairwise sexual reproduction at the cell level (e.g., "sperm and eggs"). At this point the organism is technically hermaphroditic -- there are not "male" or "female" forms. Instead each individual has the anatomy necessary to both donate sperm and produce/nurture eggs, and sexual reproduction involves a bi-directional transfer, with each of the individuals both donating and receiving sperm during the "sex act". E.g., earthworms.
6. From step 5 it's a relatively straightforward step to specialize into two separate sexes, *one at a time*. For example, a mutation could lead to a subpopulation of individuals which have lost the ability to donate sperm, but still have the capacity to produce eggs and have them fertilized. This subpopulation would not die out, since it could still reproduce by being fertilized by the remaining hermaphrodites in the population. Thus it is feasible to have a viable population consisting of a mix of hermaphrodites and "females", without specialized males yet existing. Or it could start in the opposite direction if the first "mutant" subpopulation involved individuals which lost the ability to produce eggs, but still had the capacity to fertilize the remaining hermaphrodites (i.e. "males"). At this point the "specialists" (that is, the "males" or "female" subspecies as the case may be) would be expected to specialize even further in become better DNA "donors" or "receptors", and this would create a genetic "arms race" which would be likely to cause members of the remaining hermaphroditic subpopulation to eventually specialize into the "other" sex, although that could take a lengthy amount of time. But the point is that it needn't arise overnight to "match" the appearance of the "first" sex, as might appear at first glance.
As for *why* sexual reproduction (i.e. why couldn't life have just gotten by for several billion years asexually), there are various forces at work. The first is that the "shuffling" that takes place during DNA exchange produces vast amounts of new variation, far faster than occurs during asexual reproduction. This buffers a species against being wiped out by various challenges, such as environmental changes, a new predator, a new disease, etc. The more that the individuals in a species resemble "clones" of each other, the more they can *all* be felled by a single adverse event which they are all vulnerable to in the same way. With higher variation, statistically many individuals will by chance be less susceptible to whatever adversity strikes the population.
Also, evolution takes place much faster in species which reproduce sexually than in those which reproduce asexually (for a given generation time and birth rate). In a sense a creature that reproduces asexually is its *own* "species", since it doesn't interbreed with any others of its kind. If beneficial mutation "A" takes place in one asexual bacterium, and beneficial mutation "B" takes place in the bacterium right next to it in the petri dish, those two beneficial mutations will never come together, not even in future generations, in order to make a "doubly blessed" individual. But in a species with sexual reproduction, *all* the beneficial mutations that occur in *any* individuals have the potential of being "shuffled together" in a subsequent generation in order to produce individuals which benefit from *all* of those beneficial mutations. Evolutionary "advancement" is greatly facilitated. (And even the creationists who claim not to believe in "macroevolution" should be able to see how this still helps to make beneficial "adaptation" vastly more efficient.)
So through a variety of effects, species which acquired sexual reproduction (with or without separate sexes) would be expected to "outevolve" those species which had not. And as you look around, you'll note that indeed most "complex" organisms reproduce sexually (including plants), and even unicellular organisms frequently do so or find a way to achieve similar outcomes (e.g. "lateral transfer" of DNA in unicellular organisms).
Why two sexes instead of a world of hermaphrodites? Presumably because having specialized males and females opens up more possibilities for more efficient functioning by each. Also, have a two-sex system *enforces* sexual reproduction, whereas hermaphrodites can often "fertilize themselves" -- which combines the worst aspects of both sexual and asexual reproduction with few of the advantages.
As a sidebar it's interesting to note that some animals (which ordinarily reproduce sexually) still retain the ability to reproduce by "simple cell division" at times. Through a process known as "parthenogenesis", females of the species produce a diploid egg cell which is a "clone" of its own DNA, and female offspring are produced without any fertilization by any male (a true "virgin birth"). Animals which can do this include some species of insects (e.g. aphids), fish, amphibians, and reptiles. And apparently a kind of half-assed parthenogenesis has been found to occur in domestic turkeys.
Why *only* two sexes? Probably because while there is a direct route for the production of specialized male/female forms from hermaphroditic beginnings, there doesn't seem to be any obvious way to produce *three* types, nor would there be any obvious advantage to doing so (and several obvious disadvantages).
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