Radiolarian skeletons swarm in the background while a Pterodactylus elegans splays out his limbs in a futile effort to stay alive.  We are starting here with observations, not mere suppositions.  The Truth Tree's position on evolution is that it is solidly based on observation and is not mere speculation.   One might criticize the history of the American Revolution because no living person saw it take place, but the indirect evidence is overwhelming.  Can anyone doubt that our flying reptile above was alive at one time?  TheWhite Cliffs of Dover are made of radiolarian skeletons and the calcareous remains of foraminifera and other similar organisms.  Can anyone doubt that these tiny skeletons settled to the bottom of seas long ago as they are doing today?  And can anyone doubt that the Earth is billions of years old?

The following can all be verified by observation:

All living things on this planet grow and reproduce by the process of copying very large DNA molecules, or in the case of some viruses, RNA molecules.  If all the species of plants and animals were "created", why would we expect them all to be based on the same molecular structure?  Someone questioned at this point that life forms are all based on the same molecular structure.  I am referring here to the molecular structure of DNA and/or RNA which I believe are known to be fundamental to all life forms yet discovered.  Mankind creates bottles, but there are stone bottles, glass bottles, metal bottles, plastic bottles, etc.  Bottles are the product of intelligent design.  The designer of these bottles is known.  If each species of life on our planet was created by an intelligent designer, there would be no necessity for basing them all on the same molecular structure.  The fact that all life yet discovered is based on that same molecular structure is simply consistent with the idea of evolution and not consistent with the idea of intelligent design.  And the discovery at some future date of life forms which do not depend on DNA or RNA wouldn't detract very much from the force of this argument because of the very near universality of those molecules.  Perhaps a good summary of this argument could be that we have clear examples of things that were intelligently designed (bottles, TV sets). In these cases different objects designed for the same general purpose are made of many different materials. When we try to account for living things we discover that although they all share many of the same purposes, e.g., motility, reproduction, metabolism, respiration, etc., they all depend for their existence and functioning on molecules which have the same basic design: DNA and RNA.  Their existence can be accounted for on the basis of the principles of variation and natural selection precisely because they share these same molecules.  And it isn't just the fact that the same molecules are shared.  It is the fact that these particular molecules have the structure necessary to produce all the observed complexity of living things.  There are no such molecules to be found in objects known to be made by intelligent design.

When the molecule is copied, it is not always perfectly copied.  This means that in the process of reproduction animals and plants vary in their characteristics.  This is what Darwin called "variation.".  It is the first of two essential ideas in evolution.  This is not just speculation.  It can be verified by observation.  Look at any living organism through successive generations and you will observe that many changes occur from one generation to the next.  This does not happen in objects which are known to be intelligently designed.  For such objects the existence of millions of virtually identical examples is common.  These objects change only when their intelligent designer decides to make changes in them.

Organisms which have inherited characteristics that increase the likelihood that they will reproduce pass on these characteristics to their offspring.  This is the second essential idea in evolution.   Darwin called it "natural selection.".  This is not mere speculation either.  It can be observed to happen.  It can also be produced "experimentally".  Consider the breeding of domestic animals.  By selecting desired characteristics a strain of sheep or cattle can be bred which has those characteristics.

Given these two principles we would expect to see exactly what we do see:  the emergence of species adapted to different environments and the extinction of species which failed to adapt.  At issue, of course, is the time factor.   Clearly it would take millions of years for these principles to produce the wide variety of plants and animals we see on Earth today.  It was once thought that Earth was only a few thousand years old, but the evidence is quite conclusive that Earth is several billion years old.

Some people become indignant when these ideas are presented to them because they believe that their religion is being attacked.  This is because they have the idea that religion is competent to tell us the nature of reality.  This idea is quite ancient, but it is not respectable.  It is precisely by doubting that idea that science has progressed.  In recent years there has been a curious resurgence of skepticism about evolution.  Books have been written attempting to convince the public that what their authors call "the theory of evolution" has fallen into disrepute and that something they call "creation science" deserves to be given equal consideration in biology courses.  These proposals deserve vigorous opposition.  There is no basis for any of their arguments, and their "creation science" does not deserve much more than a few moments' serious consideration.

An argument that is frequently put forward by people who want to challenge the idea of evolution is that order cannot arise from chaos.  At least, that is what they believe.  But is it true?  The first law of thermodynamics says that energy can neither be created nor destroyed.  The second law says that in any closed system entropy (a measure of disorder) must increase.  These laws have convinced cosmologists that our universe must eventually "run down" with the distribution of energy in space becoming increasingly uniform over time.  But living things are not "closed systems".  They are "open systems.".  The second law of thermodynamics is similar in some ways to the idea that water always runs downhill.   Let's say for purposes of argument that "water always runs downhill" is a scientific law.   Does this "law" mean that water can't run uphill?  Of course not.  As a matter of fact, in running downhill water can do work as in a hydro-electric plant, and the energy can be used to pump water uphill.  An ancient method of irrigation was to let the flow of water drive an Archimedes screw that in turn pumped water uphill and irrigated the crops.  These examples illustrate that an increase in entropy in one place can be used to create a decrease in entropy (that is, an emergence of order) in another place.  The Sun is gradually losing its energy.   But some of its energy falls on our planet and strikes molecules of chlorophyl thus resulting in the storage of chemical energy.   Life in no way contradicts the laws of thermodynamics.

Creationist literature contains frequent allegations that there are no "transitional forms" in the fossil record.  This is simply not so.  Remember that reconstructing the history of life on our planet from fossils is like reconstructing a copy of the New York Times that has been retrieved from a fire.  The newspaper has been separated into a thousand fragments and most of the information it contained has been lost.  No wonder we don't find all the steps in the chain of evolution!  Another misconception related to transitional forms is to think that evolution would require some transitional form between, say, a dog and a cat.  The absence of such an intermediate form is then considered evidence in favor of creationism.  But dogs did not evolve from cats, and cats did not evolve from dogs.  They had a common ancestor somewhere among the early mammals, but there should not be any actual animal that is intermediate between a dog and a cat.   Our modern dogs and cats are on two different branches of the evolutionary tree, and ever since those two branches started diverging dogs and cats have become less and less alike.  They have also become very unlike the common ancestor.  So if we could actually identify their common ancestor, it would look neither like a dog nor a cat except that it would have four legs, a vertebrate endoskeleton, fur, and give birth to live young, feed its young with mammary glands, and have a true placenta like all the other mammals.   It would not be "intermediate" in any sense.

The "young earth creationists" believe that the age of the earth is not much more than six thousand years and that the age of the universe is not much more than the age of the earth.  One of our participants listed twenty-four "reasons" in support of the "young earth" hypothesis.  Tim Thompson has done an excellent job of refuting all twenty-four of these arguments here.  The average reader is probably not equipped to evaluate arguments of this kind which often involve suppositions about galaxies, star clusters, interstellar dust, meteorites, and other astronomical information.  Creationists like to present information about some of the conflicting information regarding the age of the universe and use the fact of conflict to urge their readers to think that scientific cosmology is in terrible disarray. At times in the history of science there have been many examples of data that didn't fit the current theoretical framework.  This is perfectly to be expected and is the way progress is made.

There is also another kind of example which shows how order can arise from chaos.  We have shown above how the second law of thermodynamics does not apply to open systems such as a planet with a convenient source of energy nearby.  This new example is based on information and not energy in the usual sense.  It is a "cellular automaton" created by a mathematician named John Conway.   He calls it "The Game of Life." Go to Conway's Life or Introduction to Life to see how this mathematical model works.  The "game of life" demonstrates concretely that order can arise from disorder and just simply demolishes all arguments to the contrary.  The first site features a Java applet that runs in real time. Click on the "Enjoy Life" button.  You will see a grid like a checkerboard.  Each cell in this grid can be either "alive" (if it is filled in) or "dead" (if it is blank).  Here are the rules:.  If a living cell has 0 or only 1 live neighbor, it dies of loneliness. If it has 4, 5, 6, 7, or 8 live neighbors, it dies of over- crowding.  A living cell with two or three live neighbors survives to the next generation.  If a dead cell has exactly three live neighbors, it comes to life.   I recommend that you resize so that the grid pattern fills your screen.  Then just move your mouse pointer near the center of the screen, hold down the left mouse button and drag back and forth with the mouse so that you create a real mess near the center of your screen.  Don't be afraid to create a fairly large mess that is mostly black on the inside and has lots of messy lines and jags sticking out from the sides.  Now just click on GO and watch what happens.  You have created a disordered mess, but occasionally an organized pattern will appear entirely by chance.  These organized patterns are called "gliders" because they replicate themselves (like DNA molecules) and thus appear to move across the screen.  If you don't get any gliders the first time, try again and make an even bigger mess.  Sometimes several gliders will develop from one mess.  There are many other interesting forms that can occur spontaneously. 

There is a common misunderstanding of the importance of cellular automata such as Conway's.   For example, one of our participants said, "All right.  These 'gliders' certainly do appear on the computer screen.  But they didn't arise 'spontaneously'.   They were created by Conway!  After all, he wrote the program, and the program can't do anything that he didn't tell it to do.  I think the example is an argument for creation!"  But this is exactly the same as saying that there are really no rings around Saturn and no moons revolving around Jupiter.  When Galileo said, "But you can see them in my telescope", it can be argued that, after all, Galileo made the telescope and it therefore can't show anything that he didn't "tell" it to show.  (As a matter of fact, such arguments were actually made against Galileo's telescopic observations.  In particular, the Church of his day were offended by his observation of the moons of Jupiter because they tended to exemplify the rotation of the earth around the sun.  Some of the clerics of that day refused to look through the telescope!)  The cellular automata are computer simulations of sets of hypothetical elements and rules for the behavior of these elements.  The programmer does indeed create these elements and rules.  But then the "gliders" and other complex entities arise completely without any intervention from the programmer.   Perhaps there was a creator of the elements and rules of our universe.  But if so, this act of creation occurred before evolution began.  Darwin's theory does not try to explain the existence of the universe, nor does it claim to explain the existence of life.  It merely starts with the universe as we find it and life as we find it and then attempts to explain how species arose, developed, changed, and diversified.  Questions regarding the origin of the universe and the origin of life are very interesting questions, but they are completely outside the domain of evolution.   So there are two confusions here.  The first is in thinking that the programmer of an automaton created the orderly entities that emerge from disorder when the automaton is run.  The second is in confusing arguments about evolution with arguments about the origin of life and the universe.

There has been much incredulity in recent popular literature regarding the ability of the principle of natural selection to account for evolution all by itself.  One family of proposed cures for this problem goes by the name of intelligent design.  This is the old élan vital strategy harking back to the days of vitalism:  if you can't explain how something happens you postulate a special explanatory principle and give it whatever attributes it needs to explain observed events.  Such a strategy is strikingly unscientific.  Some of these intelligent design arguments are frankly theological, but there are other versions which ascribe the intelligence to extraterrestrial beings or leave the postulated intelligence conspicuously undefined.  The position taken here is that while incredulity is certainly understandable, the case for impossibility has not been proven and indeed probably can never be proven.   But if other mechanisms did operate to accelerate the process of evolution, such mechanisms are just welcome additions to our understanding of what happened.  These additional mechanisms need only be spelled out and investigated.  Some argue that Darwin had to be wrong because evolution didn't always proceed as gradually as they think Darwin's position requires.  But it is difficult to see why relatively rapid periods of evolution could not occur under the assumption that natural selection is the only mechanism operating.  Environmental change certainly would have an influence on the rate of evolution.   In addition, a respectable attempt has been made to come up with a theory of "self organization" in complex systems by Kauffman in his book, At Home in the Universe.   Kauffman points out that complex systems often display a degree of order which is inherent in the system and the way in which its components interact.  This order doesn't have to be explained by a tedious trial and error process such as natural selection.   It is what he calls "order for free" and could go a long way to reducing the incredulity which one may experience in contemplating a naturalistic explanation for life.  He uses computer models to support his ideas. 

It is often claimed that belief in evolution is no different from belief in religion.   Biologists are often depicted as being dogmatic "evolutionists".  Biologists are, of course, human.  In their debates with creationists and intelligent design advocates they can indeed become dogmatic and emotional.  And so can their opponents!   This is a mistake, but we should forgive it on both sides of the argument because we humans are naturally emotional and subject to making numerous kinds of mistakes.   But natural selection is not a dogma.  It is first of all an observable process.   Observing natural selection taking place on a small scale of course doesn't "prove" that natural selection accounts for every living thing on the planet.  I don't think it would be scientific to believe dogmatically that natural selection does account for all the variety of living things.  Natural selection is a working hypothesis which, when explored, has led to the astounding advances in biology in the last century and a half.  It is a working hypothesis, therefore, which deserves continuing investigation.  In a very real sense it is one of the central ideas in biology, and leaving it out of the curriculum would be absurdly unacceptable.  The hypothesis of intelligent design postulates something that is intelligent and capable of designing.  It would be fair to ask about the properties of this something.  The only intelligent somethings that we have ever observed have brains.   It would be reasonable to ask if the something that designed living things also has a brain.  It would be reasonable to ask if it has a liver and whether its liver cells store glycogen.  We might ask if it has toenails and whether it has to cut them from time to time.  These are the kinds of questions which naturally occur to anyone seriously investigating a hypothesis.  The fact that these questions seem ludicrous is perhaps some indication that the hypothesis of intelligent design is very different from that of natural selection.  Questions about the hypothesis of natural selection have led not to absurdities but to astounding advances in the science of biology.  The argument for intelligent design begins with incredulity that some complex structure or process could ever have arisen through natural selection or any other naturalistic process.  This leads to attempts to "prove" that certain things could not have arisen in any such way.   Proving that something is impossible has a long history of spectacular failures.  The only field where it has succeeded is mathematics where it is possible to exhaust all avenues for a proposed process (such as trisecting an angle with ruler and compass).   I am reminded here of the well known quip, "The difficult will be accomplished immediately; the impossible will take a little longer." And if you have ever parented (or, for that matter, been) a teenager you must certainly be aware of the scenario in which the assigned task "could not possibly be done". 

One of our participants questioned whether Darwin's theory actually has made a contribution of importance to biology.  He thought that important advances like the development of antibiotics could have happened without the idea of evolution.  Of course some advancement can be made and has been made in biology without that idea.  After all, biology made progress before the theory was stated in 1859.  But evolutionary thinking clearly lay behind the search for the molecular structure of DNA.  If it had not been for Darwin's theory, who would have even thought that such a structure was there to be discovered?  I strongly suggest that anyone interested in this debate read Watson's book, The Double Helix.   And consider the impressive progress that has been made in discovering the physiology of nervous systems.  Looking at the nervous systems of animals at different stages along the phylogenetic tree has provided important clues in the effort to relate structure to function.

And one more argument against intelligent design needs to be made.  In the mammalian eye (and that includes your eye, dear reader) the bed of rods and cones in the retina lies behind a network of capillaries which supply the blood needed to nourish the cells of the retina.  All your life you have been looking at the world through this network of tiny blood vessels.  These capillaries cast shadows on the light sensitive rods and cones.   Why don't you see these shadows?  The answer is that they do not move.  A little known fact of vision is that if an image on your retina is stabilized it disappears.  The image of the shadows of these capillaries is stabilized because virtually all the light entering your eyeball comes from one direction and the shadows don't move.  This makes them invisible.   Take a small pencil flashlight, close your eyes, place the tip of the little light bulb against the eyelid near the outer corner of your eye, and jiggle it up and down for a few seconds.   You will now be able to see the branching pattern of those capillaries in your eye that you never have seen before because their shadows are now moving.  This is because the source of the light is moving.  Now if the eye had been designed by an intelligent designer, why wouldn't the capillaries have been placed behind the light sensitive rods and cones?  The eye of the octopus has that arrangement.

Another example of the contribution of Darwin's theory to progress in biology was provided by J. Craig Venter who told the following story in his book, A Life Decoded. He was attending a meeting where a Catholic priest made the statement that no human gene should be patentable.  Venter asked if he thought it would be okay to patent a yeast gene, and after a moment's thought the priest said yes, it would.  Then Venter asked him what he would say if the yeast gene were exactly the same as a human gene (he named a gene that was identical in yeast and humans).  This apparently shocked the priest, who believed that humans are so far removed from yeast that no human gene could possibly exist also in yeast (or conversely).  The existence of genes which are shared by widely different organisms conclusively demonstrates the kinship of all living things on this planet.  Such a kinship is a direct consequence of Darwinian evolution, but just doesn't make any sense under the intelligent design theory.  (This citation was suggested by Lloyd Milligan.)

In Dover, Pennsylvania, a group of intelligent design advocates on the local school board attempted to introduce an auxiliary text which they thought would introduce a much needed "balance" in the curriculum.  The book, Of Pandas and People, points out that "spontaneous generation" was false.  It then goes on to try to refute evolution and present a theory of intelligent design.  A group of parents objected to the introduction of this non-scientific book as a text in biology classes and took the school board to court.  To read the resulting court decision, go here.  The response of the intelligent design advocates can be read here.  I won't discuss the obvious inadequacy of the ID advocates' press release but hope that readers will debate the points they raise in the Evolution Forum.  Their argument is that science is a religion.  The fundamental differences between science and religion are discussed in the Religion Position Statement.  One of our participants said facetiously that if science and religion are indistinguishable we are forced to decide which snake oil to buy!  I suggest that we buy the snake oil that really works!