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 are played 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 similar to 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 each voice (planet) is playing its own variations on the main theme. So where's the fugue in this episode? Although there is some Baroque-sounding music, ironically, there is no fugue 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 to evolution on religious or ideological grounds, and try to maintain some intellectual "wiggle room" that allows them to deny evolution. Sagan takes one of the most widespread of these scams head-on.

As used by many people, "theory" means "hypothesis", therefore a guess that can be disregarded. But "theory" in science actually refers to any coherent, organized body of ideas. The structural integrity of the Sears Tower was calculated using "stress theory" but nobody believes the Sears Tower was built using guesswork or unproven hypotheses. The portion of music training that describes notation, chords, and harmony is called "theory" although its basic ideas have been highly refined and workable since before Bach.

If evolution really happened, then its opponents are wrong, and they will have to deal with 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. This is one of the meanings of the dictum "Science is Value-Neutral"; if scientific findings 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 are more likely to find the truth by following the evidence honestly than by tailoring findings to fit a preconceived belief system.

Discovery of Evolution

Evolution by natural selection was discovered by Charles Darwin and Alfred Russell Wallace. 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 when he got a letter from Wallace outlining the theory. What could have been a seriously nasty priority 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 ensure that Wallace got a fair hearing for his ideas. Wallace, for his part, actively defended Darwin and his writings. Historians now give both scientists equal credit for the discovery.

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

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 unmistakable 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 organisms occur.

Observational Evidence

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

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 occurs 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, occur and then an organism evolves to a new form. But if you randomly tinker with the engine of your car or some electronic component in a computer, you will virtually certainly make things 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 huge number of organisms to work with. If the chance of a beneficial mutation occurring are one in billions, but there are trillions of organisms during the lifetime of a species, some will 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 organisms move into new environments (say colonize remote islands), their mutations may become useful or at least harmless. Island organisms, free of competition, tend to radiate rapidly into all kinds of specialized forms. They also tend to be easy prey for the more generalized organisms from the continents. That's one reason why humans have deliberately and unwittingly driven so many island organisms to extinction.

Prebiotic Evolution and DNA

DNA

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

A human body contains about 20 trillion cells. The total length of DNA in a human body is thus 20 trillion meters, or twenty billion kilometers, the circumference of the orbit of 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, but it 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 in Serbo-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 way you don't understand.

Is the following number sequence random: 592653589793238462643383279?
It not only looks random: it is random. This particular number sequence has passed every 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 to predict the trillionth digit of pi is to calculate it. You can guess the next decimal digit of 1/3 with 100 per cent accuracy. If you try to predict the next digit of pi your overall accuracy is ten per cent. So one very important meaning of "random" is that something cannot be predicted with better accuracy than that predicted by statistics. This unpredictability can occur even in something as precisely defined as pi.

One important reason why things may be unpredictable is lack of information. If you pick a date in the past or future and guess the positions of the Moon and planets, you will do no better than random guessing, even though the positions of the planets can be foretold with high accuracy. Since you don't carry formulas for the motions of the planets in your head, your guesses will have no accuracy. I omit the Sun from this discussion because 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. But note 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 to the same accuracy. If you had absolutely precise information about the forces on a coin and 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 of randomness 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 its own simplest description.

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

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

Can Order Arise Naturally?

The Second Law of Thermodynamics is often paraphrased as "things always go from bad to worse." Most popular descriptions describe it as "disorder in the Universe is always increasing." The law is often illustrated by dumping a jigsaw puzzle on the floor and imagining the likelihood of it spontaneously self-assembling. But the actual concept at the core of the Second Law is something called entropy. In discussing 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 no relevance 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 that system. But, at the same time, you are expending energy to move the pieces around and perform the mental tasks needed to solve the puzzle. Complex organic molecules you ate a few hours ago are broken down into simpler molecules, some of which are exhaled as carbon dioxide and water vapor. Liquid water in your body is vaporized as perspiration. The puzzle as a whole has gone to a state of lower entropy, but the entire system - you, the puzzle, your food, the surrounding atmosphere, has gone to a state of higher entropy.

It is possible for water to run uphill, over rocks in a stream perhaps, if it's first picked up speed by falling. Similarly, entropy can decrease locally, if entropy in a larger 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 random in 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 chance of 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 water evaporate. The chances of sodium and chlorine atoms arranging by chance in a rigidly cubic alternating array is zero, but it doesn't happen by chance. The sodium atoms have a positive charge, the chlorines a negative charge. The opposing charges attract and like charges repel. The chance of their arranging this way is virtually 100 per cent.

Some people have attempted to calculate the likelihood of forming complex organic molecules as if the molecules assemble by random addition of components. Of course the probability of forming a molecule that way is vanishingly small because molecules don't form like that. The missing half of a replicating DNA molecule spontaneously assembles from simple organic molecules in the cell (see above). A simple-minded probability calculation 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 billions. 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 read each 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 inevitable on 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 Code Most mutations harmful Structure of DNA - how deduced? Invention of "sex" O2, N2in Atmosphere Cambrian "Explosion" Difficulty of evolving complex organisms Extinction 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" Lightning and 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