The godly algorithm (61: origin of earth life)

Option 2. Life may have originated when lightning struck warm soupy water, perhaps at the shallow edges of earth’s early seas. In 1871 Charles Darwin wrote in a letter to his friend Joseph Hooker that life on earth may have begun in “a warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. present, so that a protein compound was chemically formed ready to undergo still more complex changes.”

 

Darwin’s conjectures, like his evolutionary theories, were highly credible. In 1952 graduate student Stanley Miller and his professor, Harold Urey, conducted a now-famous experiment showing that organic molecules actually could have formed, spontaneously and naturally as Darwin speculated, from inorganic materials in conditions present on the early earth. After a week of sending electric sparks through an inorganic mixture of water, ammonia, methane and hydrogen, up to 15 percent of the carbon enclosed within the experiment was transformed into various organic compounds of the kind that “can” become alive. These compounds significantly included five amino acids, which are the building blocks of proteins at the foundation of life. A more recent re-analysis of the experiment’s products identified twenty-three amino acids. The experiment was credible.

 

A sophisticated modern variation on the same theme occurred in 2010 when a team of scientists at the J. Craig Venter Institute extracted genetic code from the DNA of a bacterium, Mycoplasma genitalium, and inserted it into a second bacterial species. The result was a hybrid lifeform that reproduces itself—the first lifeform with a human-generated artificially synthesized genome. They named it Synthia, though others call it Mycoplasma “laboratorium.” The unusual project did not “create” life, nor does it explain the process by which that first complex molecule reproduced and became “alive” as we would define life. But it certainly is playing around the threshold of a new door.

 

People are stepping through such doors. Harvard biologist Jack Szostak led a team that in 2013 showed that common citrate, a cousin of citric acid found in limes and lemons, enables the hereditary RNA molecule to copy itself. “Our goal,” he says, “is finding some reasonable and continuous pathway from small molecules up to more complicated building blocks, then to cells that can start to evolve.” If scientists keep on in this manner they may actually hit on a believable scenario as to how life originated on planet Earth. But—here and now, several billion years later—no one will ever be absolutely sure.

 

Always look for the third option. Having only two often results in bipolar disputations, especially where churchmen and scientists are the principal disputants. On the origin of life, let it be noted that only science has provided options which may be called credible, whereas religion’s options differ with every different religion, including Big Turtle. On the other hand, there obviously is no reason, no reason at all, for scientists to feel smug.

 

Option 3. Life may have originated in the deep ocean depths, around very hot vents from which mineral-rich water rises up through the ocean floor. We know that certain heat-loving bacteria survive and thrive around such vents They convert inorganic molecules such as hydrogen sulfide into sugars they can eat, just as plants employ photosynthesis to ingest carbon dioxide and give off oxygen. It’s a plausible option, and could be true even if life also originated in other ways elsewhere, such as the n options below.

 

Option 4. Life may have been carried to earth on comets, meteoroids, or rock fragments flung here from meteoritic impacts on our sister planets. All three possibilities carry the condition that life first originated elsewhere in the universe, or on some other planet in our own solar system. Extraterrestrial origin(s) of life is a perfectly feasible hypothesis. Organic chemical compounds, for example, are commonly found in meteorite fragments from both within and outside the solar system, and such compounds are spectroscopically deduced in the ice and sludge of which comets are made.

 

Regardless of source, we know that life most certainly did appear once, here on earth, so who’s to say it may not have happened many other times in many other places across this humongous wide universe, even if nobody was out there to record it in a Cosmic Bible? Organic traces do indeed appear in the fragments of rocks dislodged by meteor strikes on other planets and flung into earth’s gravity well. And scientists are all over those signs of fresh water flowing on Mars, because we know where there’s water there could be life. Yes, extraterrestrial origin of life is a wholly credible possibility.

 

Options n. Life may have originated in different places on earth, in different ways, and perhaps many times. Extremophile bacteria have been found alive and well—and reproducing—in water near the boiling point, beneath glaciers hundreds of feet thick, and in rock more than a mile underground. In all these places they subsist by “eating” things you wouldn’t think living things could live on, but they do. Life clearly has some fragile aspects, but equally clearly it is very hardy—and simple life seems hardier than complex life. An internet query on “life origins” will put you in touch with a bewildering batch, beyond those listed here, of options, facts, learned opinions and wild speculations.

 

One of these latter offers back-door learning via an interesting article in which scientist Casey Luskin lists the top five problems with current origin-of-life theories. You can learn a lot about an idea by reading the railings of critics’ who dislike it. Biblical scholars have in fact used this method to discover a great deal about the various early Christian sects by studying the writings of Gnostics who competed with them, and writings of the churchmen who despised the Gnostics. As I’ve said, there is nothing in science about which scientists do not argue, sometimes vehemently while growing red in the face. But, other times, the humility of truly open mindsets gleams through, as in the comments of Harvard chemist George Whitesides during his acceptance speech upon receiving the Priestley Medal, the highest award conferred by the American Chemical Society:

            The origin of life problem…is one of the big ones in science. … Most chemists        believe, as do I, that life emerged spontaneously from mixtures of molecules in          the prebiotic Earth. How? I have no idea.

 

Life in the universe

Life is here, therefore it began somewhere, this much is certain. But why? Did God create life as Genesis says? Did life just happen accidentally, in an evolutionary sort of way? Our questioning intellects, functioning in the image of God, quite appropriately wonder how it began, and when and where, and most of all why. Such reasonable questions.

 

Let’s dig a little deeper into that space option. We can logically cross off an origin in the raging million-degree heat of a star, and it probably did not happen in the cold empty space between stars and galaxies where there’s not much to eat. But maybe on a planet orbiting some star? Seems reasonable. But, the odds makers insist, it’s a big universe—are there enough planets out there for this life thing to maybe get started on?

 

In the preceding chapter we noted there are roughly 200 billion galaxies in the universe (estimated range 100 to 500 billion). Like our Milky Way, each galaxy has maybe 200 to 400 billion stars (estimated range a bit less to a whole lot more). Multiplying then, we discover there are some quintillions or sextillions—maybe even septillions—of stars in the wide universe. Quite a few, say. Now, science has in recent times learned that a large percentage of these quite-a-few stars are orbited, just like our sun, by at least one planet. Many stars have a half dozen or more. So, roughly, how many planets that life might have begun on are out there in the universe?

 

Suppose a low-ball guesstimate that fifty percent of all stars have, on average, only two planets (accumulating evidence suggests this is way below average). Multiplying again to get a rough total number of planets; you get a real brain buster of a number. But planets are quite a mixed bag—some are covered with methane ice, some are too gaseous, too big, too cold, too something. Many could not possibly support anything we’d recognize as life. So:  on how many of these zillions of planets might life have begun? Guesstimate again: say very, very few—call it only one thousandth of one percent (0.001%)—may support life. And multiply again…  The resulting number is so very big you likely cannot get your mind around the heavenly host of planets that might support life. And that’s just the low-ball guesstimate. Our universe is a real big place.

 

The fact is, high-precision observations over recent years strongly suggest that most stars in all galaxies are surrounded by multiple planets. As we learn more each year, strongly “suggest” is becoming strongly “indicate.” It makes sense, considering how stars and their planets form simultaneously within a condensing ball of hot gas and debris. Several thousand “exoplanets” orbiting other stars have now been identified, and the number grows daily. Plus, there are said to be trillions of “rogue” planets roaming space, unattached to any star, just in the Milky Way alone. Any way you approach it, there are plenty of planets available to serve as cradles for the appearance of life.

 

A significant minority fraction of these candidate planets are reasonably similar to Earth, and that minority is a Very Big Number. Factual data now support the prospect of a truly astonishing number of potentially life-friendly planets. If the minutest fraction of these are even minimally amenable to life, the odds that life must exist on some of them becomes a sure thing. Ask any bookie. The upward trajectory of evolution will make it happen “on average”—just like the house odds at Reno.

 

This leads us to two important considerations: 1) life very possibly may exist on lots of other worlds across the universe, and 2) life on earth may have arrived here from one or more of those faraway places. We can’t yet examine distant exoplanets up close to see if life has actually come into being on them (though we’re steadily getting there). Our sophisticated telescopic spectrometers may tell us there are life-generated chemicals in the atmosphere around some of them, but imagining anything beyond that stretches too far. We do, however, have very good evidence that life exists on the planet we call Earth, and so, as a practical matter, that just might be where all life began—unless life started elsewhere and was carried here by a comet or something. But when, and how, might that have been? For that matter, how would we know it was “alive” if we saw it?

 

What is alive?

What does it mean to say something is “alive?” As a fairly recently evolved component of the self-organizing universe (only 3.5 billion years ago, on our planet—or 10.3 billion years after the big bang), “aliveness” clearly requires, at minimum, some degree of self organization. No single atom displays characteristics we think of as being “alive,” nor does any molecule comprised of just two or three atoms bound together. But when atoms bind themselves together in various organized combinations as molecules, as they constantly do, some very large molecules have properties whereby they seem to be alive. We call such molecules viruses, and though they may be extremely small and simplistic as living things go, they represent very considerable evolved complexity along the road that leads to life. The aforementioned Mycoplasma genitalium, for example, is said to be about one five-thousandth of a millimeter in diameter. The polio virus, which is perhaps ten times smaller yet, when viewed as a molecule contains about 3.2 million atoms.

 

Neither organization nor size, however, necessarily constitutes a threshold for “alive.” We have seen that many features of the natural universe, especially galaxies, stars and planets, organized themselves into being as a response to the universal tug of gravity. As it happens, living organized things embody a characteristic that non-living organized things do not and it has nothing whatsoever to do with gravity. That characteristic is re-production of themselves. After having been “produced,” each living entity can in turn produce itself again. Reproduction, once commenced, produces a continuity of the original entity, and that continuity will be ongoing, endless, unless some event or malefactor stops it by killing or seriously damaging it. One cannot kill a non-living thing—to be “killed” a thing must first be alive.

 

…“life” is not a thing, a separate entity. It is a word used to describe the properties and activities of living substance, as observed in animals and plants; and their basic distinguishing property is their capacity for self-reproduction …reproduction depends on continuity of substance. New individuals develop from portions of the living substance of other individuals. The original individual may simply split in two, or it may detach a portion of its substance to serve as a basis for the new individual’s development.

Julian Huxley

 – to be continued in one week –

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