Cosmos #2 - One Voice in the Cosmic Fugue

Steven Dutch, Professor Emeritus, Natural and Applied Sciences, Universityof Wisconsin - Green Bay

What's a Fugue?

A fugue is a musical piece in which several overlapping variations on a theme areplayed simultaneously by different sections of an orchestra. Each section is called a"voice." The overall effect suggests rapid flight, hence the term. The word"fugue" comes from the same root as our word "fugitive."

At the risk of offending serious music lovers, the general idea of a fugue is similarto the familiar round singing of "Row, Row, Row Your Boat", except that in around, each voice simply repeats the same theme over and over ... and over ... and over...In a fugue, the theme is continuously varying and the overall organization is far morecomplex.

Sagan likens the possible variations of life in the Universe to a fugue in which eachvoice (planet) is playing its own variations on the main theme. So where's the fugue inthis episode? Although there is some Baroque-sounding music, ironically, there is nofugue anywhere in the music in this episode!

Evolution by Natural Selection

"Evolution is a Fact, Not a Theory - It Really Happened"

Here's Sagan at his in-your-face best. A lot of people, of course, are opposed toevolution on religious or ideological grounds, and try to maintain some intellectual"wiggle room" that allows them to deny evolution. Sagan takes one of the mostwidespread of these scams head-on.

As used by many people, "theory" means "hypothesis", therefore aguess that can be disregarded. But "theory" in science actually refers to anycoherent, organized body of ideas. The structural integrity of the Sears Tower wascalculated using "stress theory" but nobody believes the Sears Tower was builtusing guesswork or unproven hypotheses. The portion of music training that describesnotation, chords, and harmony is called "theory" although its basic ideas havebeen highly refined and workable since before Bach.

If evolution really happened, then its opponents are wrong, and they will have to dealwith the religious and ideological problems that raises. But that's not science's problem.Opponents of evolution created their own problems and they will have to solve them. Thisis one of the meanings of the dictum "Science is Value-Neutral"; if scientificfindings conflict with your value system, your value system must be wrong. This isanything but a "value-neutral" stance; it's a strident assertion that we aremore likely to find the truth by following the evidence honestly than by tailoringfindings to fit a preconceived belief system.

Discovery of Evolution

Evolution by natural selection was discovered by Charles Darwin and Alfred RussellWallace. Darwin had been naturalist on the famous Beagle expedition in the 1830's.He mulled over his observations for a quarter-century and was just about to publish whenhe got a letter from Wallace outlining the theory. What could have been a seriously nastypriority squabble became a model for scientific cooperation. Darwin, as senior scientist,got most of the credit at the time (and took most of the heat) but Darwin worked to ensurethat Wallace got a fair hearing for his ideas. Wallace, for his part, actively defendedDarwin and his writings. Historians now give both scientists equal credit for thediscovery.

The interactions of science and society following the discovery of evolution arefascinating, complex, and far-reaching. They are discussed in more depth at these twosites:

The Geologic Record

The geologic record contains the history of life on earth. The overall conclusions wecan draw from it are:

The physical evidence preserved in the rocks records mostly small-scale, gradual processes. Sudden and violent events do occur but are rare, and they leave absolutely unmistakeable evidence that is mostly lacking from the rocks. The idea that Earth's history is dominated by gradual processes is a finding based on physical evidence, not an assumption.
The record of life preserved in fossils shows a gradual increase in complexity with time.
Contrary to widespread misconception and even outright denial by opponents of evolution, fossil forms intermediate between major groups are well documented. We have intermediate forms between reptiles and birds, reptiles and mammals, amphibians and reptiles, fishes and amphibians.
Over most of its history, life on Earth was simple. Only in the last 15 per cent (700 million years) of Earth's history do really complex orgainsms occur.

Observational Evidence

Sagan uses the Heike crabs of Japan as an example of unconscious artificial selectionby humans. We can see that there are several different kinds of natural and artificialselection:

Deliberate selection for desirable traits by humans. We only learned to do this systematically about 1700, and only learned why it worked after genetics was discovered in the mid-19th century.
Unconscious selection for desirable traits by humans. We've been doing this for thousands of years. The cow that gives lots of milk is kept, the rest are slaughtered. The seed that gives high yields is saved and the rest eaten. But we didn't know how to breed animals and plants for specific traits until recently. But even unintentional selection can go a long way. Corn has been so changed by humans that it can no longer reproduce on its own, and its natural ancestor is difficult to identify (it's generally thought to be a wild Mexican grain called teosinte.) Would you identify a chihuahua as having derived from a wolf? For that matter, would you identify a chihuahua and a Saint Bernard as members of the same species if you had never seen dogs before?
Unconscious and unintentional selection by humans. This is "artificial" only in the sense that humans are involved; otherwise it's just natural selection. The Heike crabs are an example. Nobody intended to breed samurai crabs, or even knew it was going on. I suspect the crabs already looked pretty Japanese long before the Battle of Danno-Ura, and the myth arose afterward as a picturesque way of explaining the crabs and commemorating the battle.
Natural selection with no human selection at all. Examples of this have been observed even in historic times. Humans as change agent have triggered many changes without doing any selecting themselves. Our habitat changes select for generalist organisms and against organisms that require highly specific habitats. Humans also get selected; when disease organisms kill their human hosts too efficiently, both the organism and the humans lose their chance to reproduce. Evolution selects for more moderate pathogens and more resistant humans. Measles was only moderately serious to Europeans but lethal to Native American populations that had never encountered it before. Syphilis may have travelled in the other direction and was much more lethal to the first Europeans who got it than it is now.

We have not been observing long enough to witness the appearance of entirely newspecies but we have certainly observed enough important pieces of the evolutionarymechanism to be reasonably sure how it works:

Artificial selection has produced organisms radically different from their natural state. An extraterrestrial biologist would probably not hesitate to call retrievers and poodles distinct species, or at the very least, subspecies. True, poodles and retrievers can interbreed, but so can dogs, wolves, and coyotes, which are considered separate species.
Natural selection has resulted in dramatic changes in natural populations. The classic example is the European peppered moth. This moth occure in a light and dark form. As industrial pollution darkened surfaces in the 19th century, the dark form of this moth rapidly went from a few per cent of the population to dominant. As the environment began to clean up following the decline of coal as a fuel, the light form became more abundant again.
Microorganisms and viruses change with dazzling speed. We have to get flu shots every year because flu viruses mutate so quickly. Bacteria have evolved resistance to antibiotics in just a few decades.

Mutations

Most popular discussions of evolution suggest that mutations, or genetic changes, occurand then an organism evolves to a new form. But if you randomly tinker with the engine ofyour car or some electronic component in a computer, you will virtually certainly makethings worse, not better. Similarly, most organisms are well-adapted to their environment;any genetic change is almost certain to make them less well-adapted, not more.

If the chances of a beneficial mutation happening are very tiny, nature has a hugenumber of organisms to work with. If the chance of a beneficial mutation occurring are onein billions, but there are trillions of organisms during the lifetime of a species, somewill win the lottery.

More likely, though, is that mutations serve as genetic contingency plans. Fins thatcan double as crude legs may make you less agile in the open water, but are just theticket if you find yourself trapped in a shrinking pond. When the environment changes,some mutations that had been harmful might become advantageous. Likewise, when organismsmove into new environments (say colonize remote islands), their mutations may becomeuseful or at least harmless. Island organisms, free of competition, tend to radiaterapidly into all kinds of specialized forms. They also tend to be easy prey for the moregeneralized organisms from the continents. That's one reason why humans have deliberatelyand unwittingly driven so many island organisms to extinction.

Prebiotic Evolution and DNA

DNA

The hereditary code for humans is contained in the molecule DNA, Deoxyribonucleicacid. The DNA in humans contains a few billion pairs of molecules arranged in a spiralladder form. An atom is about 10^-8 centimeters in diameter, and each rung onthe ladder is a few atoms high, so the total length of human DNA in a single cell is abouta meter. Most cells are microscopic; the DNA fits in such a tiny space because it istightly coiled. The act of uncoiling DNA, splitting it, replicating it and separating thestrands without tangling in such a tiny space is mind-boggling. Ever put your clothes onin a sleeping bag? Imagine taking raw wool or cotton, spinning it into thread, weaving thecloth, sewing it into clothes, and putting them on in the sleeping bag. That's whatreplicating DNA amounts to.

A human body contains about 20 trillion cells. The total length of DNA in a human bodyis thus 20 trillion meters, or twenty billion kilometers, the circumference of the orbitof Pluto. The DNA in a human body would wrap around the Solar System.

Prebiotic Evolution

The basic molecules of organic chemistry are easily made: The classic Miller-Urey experiment of the 1950's showed that it was easy to create organic chemicals like amino acids from inorganic ingredients. Many of these molecules have been detected in interstellar space. Some scientists believe that inorganic precursors of life arrived on Earth ready-made during meteor impacts. The ease of creating organic molecules leads some biologists to believe that life is all but inevitable on any world with suitable physical conditions.
The first self-replicating molecule was almost certainly not DNA: Your cells contain a single-strand self-replicating molecule called RNA (ribonucleic acid). Some viruses contain only RNA. It is much more likely that RNA evolved before DNA, and quite possible that something simpler preceded RNA. The first self-replicating molecules might have been very simple.
DNA assembles from simpler materials all the time: When a DNA molecule splits and replicates, where does the missing half come from? It comes from the simple organic molecules in your cell fluids. When the correct molecule drifts into contact with the DNA, it is attached by the DNA editing molecule. None of this is done consciously. The fact that the mating hald of a DNA molecule is already there is irrelevant; you could pile lumber next to a half-built house with all the necessary tools and blueprints nearby and it would never spontaneously assemble into a house.

Randomness, Order and Evolution

Few things about evolution cause as much misunderstanding as the use of terms like"random". To most people, "random" means without order or purpose, butit has quite a different meaning in science. Consider a couple of examples:

Are the following letter sequences random: crvn, smrt, vrlo, gdje, trg?
The look random enough; most don't even have vowels. That's a problem in English, not inSerbo-Croatian. The words mean, respectively, red, death, very, where and town square. Moral:the fact that something looks random doesn't mean it is. It may convey meaning in a wayyou don't understand.

Is the following number sequence random: 592653589793238462643383279?
It not only looks random: it is random. This particular number sequence has passedevery test for randomness mathematicians have ever used on it. But lacking in meaning? No.These are the digits of pi beginning with the fourth decimal place. Not only is this avery meaningful number sequence, it is absolutely determined: the trillionth digit of piis absolutely fixed, even if we haven't yet computed it.

The Scientific Meaning of Random

The trillionth digit of the fraction 1/3 in decimal form is 3. The only known way topredict the trillionth digit of pi is to calculate it. You can guess the next decimaldigit of 1/3 with 100 per cent accuracy. If you try to predict the next digit of pi youroverall accuracy is ten per cent. So one very important meaning of "random" isthat something cannot be predicted with better accuracy than that predicted bystatistics. This unpredictability can occur even in something as precisely defined aspi.

One important reason why things may be unpredictable is lack of information. If youpick a date in the past or future and guess the positions of the Moon and planets, youwill do no better than random guessing, even though the positions of the planets can beforetold with high accuracy. Since you don't carry formulas for the motions of the planetsin your head, your guesses will have no accuracy. I omit the Sun from this discussionbecause you can guess the Sun's position from the date.

One approximation to pi is 22/7 = 3.142. A much better one is 355/113 = 3.1415929. Butnote that in each case the fractions have as many digits as the accuracy they achieve. Itis just as much work to write or remember the fractions as it is simply to remember pi tothe same accuracy. If you had absolutely precise information about the forces on a coinand the surface it lands on, you could, in principle, predict how a coin toss will turnout. It would take far more effort than simply flipping the coin. One other definition ofrandomness is that it takes as much information or effort to describe an event fully asit does simply to produce the event itself. In other words, the actual event is itsown simplest description.

In addition, some things are inherently unpredictable. We can predict climate(the overall physical conditions on Earth) with ever-improving accuracy, but weatherforecasts become increasingly unreliable after only a few days. We can predict generaltrends during an El Nino season, but whether it will snow Christmas Eve in GreenBay is still unpredictable. And mounting evidence suggests it may never bepossible; that tiny uncertainties in measurement now may result in increasingly greatdifferences as time goes by. Systems of that sort are called chaotic. They arecompletely governed by the laws of physics, but incomplete information prevents us fromachieving completely accurate long-term predictions.

We can see easily how these concepts apply to evolution: biological systems are far toocomplex to describe mathematically, we have incomplete information, and significant eventslike climate change or asteroid impact are unpredictable.

Can Order Arise Naturally?

The Second Law of Thermodynamics is often paraphrased as "things always go frombad to worse." Most popular descriptions describe it as "disorder in theUniverse is always increasing." The law is often illustrated by dumping a jigsawpuzzle on the floor and imagining the likelihood of it spontaneously self-assembiling. Butthe actual concept at the core of the Second Law is something called entropy. Indiscussing order and evolution, the only concept that is relevant at all is entropy.Intuitive notions of whether one outcome is more disorderly than another are of norelevance whatsoever. Entropy often corresponds to our intuitive notions of disorder,but not always.

For example, when you assemble the jigsaw puzzle, you are reducing the disorder in thatsystem. But, at the same time, you are expending energy to move the pieces around andperform the mental tasks needed to solve the puzzle. Complex organic molecules you ate afew hours ago are broken down into simpler molecules, some of which are exhaled as carbondioxide and water vapor. Liquid water in your body is vaporized as perspiration. Thepuzzle as a whole has gone to a state of lower entropy, but the entire system - you, thepuzzle, your food, the surrounding atmosphere, has gone to a state of higherentropy.

It is possible for water to run uphill, over rocks in a stram perhaps, if it's firstpicked up speed by falling. Similarly, entropy can decrease locally, if entropy in alarger sense increases to make up for it. Spontaneous order arises all the time in nature,but always as the result of a larger increase in entropy somewhere else.

Although we speak of random motions of molecules in the origin of life, we mean randomin the sense of statistically complex. Chemical reactions are not random. Forexample, if we had a bucket of dimes and pennies and dumped them on the floor, the chanceof their arranging like this would be negligible:

PDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPD DPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDP PDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPD DPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDP PDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPD DPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDP PDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPDPD

Yet the atoms in table salt have precisely the same arrangement:

It's easy to form salt crystals naturally: just let a container of salt waterevaporate. The chances of sodium and chlorine atoms arranging by chance in a rigidly cubicalternating array is zero, but it doesn't happen by chance. The sodium atoms have apositive charge, the chlorines a negative charge. The opposing charges attract and likecharges repel. The chance of their arranging this way is virtually 100 per cent.

Some people have attempted to calculate the likelihood of forming complex organicmolecules as if the molecules assemble by random addition of components. Of course theprobability of forming a molecule that way is vanishingly small because molecules don'tform like that. The missing half of a replicating DNA molecule spontaneously assemblesfrom simple organic molecules in the cell (see above). A simple-minded probabilitycalculation would put the probability at near zero; actually it is virtually 100 per cent.

Two General Principles

No discussion of order and evolution has any value unless it includes a rigorous and accurate discussion of entropy. Entropy, not intuitive ideas about order or disorder, is the only thing that counts.
No treatment of chemical reactions as random events has any value. Chemical reactions are not random.

Artistic Conventions

This video is an excellent place to observe the role of artistic conventions inportraying science. Some of the conventions used in this video include:

Anthropomorphism: Attributing human characteristics to non-human entities. For example, the DNA copying enzyme "knows" how to do its task.
Accelerating Events: The film of lymphocytes devouring bacteria is speeded up. Even more, the animation of evolution is speeded up by a factor of bilions. It creates the impression that evolution was more linear and much faster than it was.
Picturing the invisible: What does a strand of DNA "look" like? It's narrower than a wavelength of light; a light wave won't reflect off a strand of DNA any more than a huge ocean wave will bounce off a pebble. Depictions of atoms model most of their important physical properties in ways that aid visualization, but we have to remember that they are visualizations. At scales smaller than the atomic, matter takes on complex properties of both particles and waves, and no single image will accurately represent matter completely. We can emphasize one feature or another, but not every property at once.
Bringing the past to life: What color were dinosaurs? What sounds did they make? We simply don't know. Artists can give greater realism to images of the past by including plausible guesses about such details, but it's easy to forget that they are guesses.
What if?: Artists can show images of hypothetical planets, such as the one that closes the video. The best of these are based on careful science and stand up very well. Stanley Kubrick's 2001: A Space Odyssey was made before the first manned lunar landings but is so accurate that it set the standard for all future space films. Other images are more hypothetical and not as likely to be verified in the near future. It can be easy to forget that these images are just imaginary. They can even show us things that never were, say a world where Rome never fell or the Nazis won World War II.

Significant Points

Refer to the links above for some of these items:

What role did each of these people play in the development of evolution:
- Linneaus
- Lamarck
- Hutton
- Lyell
- Darwin
- Wallace
- Mendel
What was Darwin doing on the Beagle?
How did Darwin and Wallace react to their simultaneous discovery of evolution?
What are some of the principal ideological abuses of evolution?
Why do fundamentalists reject the idea that evolution is "just God's way of creating life?"
Where does the term "fundamentalism" come from?
What happened during the Scopes Trial?
How does evolution by natural selection work?
What does the geologic record tell us about conditions on Earth and the evolution of life?
Describe the structure of DNA
What's the popular view of mutations? Why is it wrong? How do mutations operate?
What is entropy? Why is it relevant to evolution?
Why are treatments of evolution based on probability wrong?
What does the term "random" mean in scientific contexts?

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Created 13 January 1998, Last Update 27 April 1998

We need plants more than they need us All living things use some chemistry Can readeach others DNA How do biological processes work? Mechanism vs vitalism? Atoms in DNA =Stars in Galaxy Few dozen nucleotides added/sec All life C Based H20? Is life inevitableon suitable worlds? Darwin/Wallace Mutations Cosmic Calendar - Age of Universe = 1 yr 1mo~1.25 by 1 day~40 my 1 hr~ "Organic Soup" model "Accident" DNA CodeMost mutations harmful Structure of DNA - how deduced? Invention of "sex" O2, N2in Atmosphere Cambrian "Explosion" Difficulty of evolving complex organismsExtinction of Dinosaurs - why? Fugue 568 Evolution - cartoon COSMIC FUGUE Carbon life -interstellar molecules Evolution inevitable? Invention of Sex Sky made by Life Cambrian explosion Dinosaurs 160,000,000 yr = 30,000 Recent history 5,000 yr 1 day history = 80years din. Chlorophyll - Hemoglobin Anthropomorphism "Mad Scientist" Lightningand UV Genetic Engineering - what to do? Molecules of Life "Mad Scientists"scenes CH4, NH3, H2O, etc. Life elsewhere? Speculations - Jupiter Predictive theories -biology and history