Why Darwin was rightand why it matters
A talk given before the Space Coast Freethought Association on Feb. 5, 2006
By George A. Ricker
Charles Robert Darwin was born on Feb. 12, 1809the same date as Abraham Lincolnand published The Origin of Species 50 years later. Neither science nor religion has been the same since.
Today Im going to talk about Darwin and why he was right. Im also going to talk about why it matters.
But before we begin, I must offer this caveat. I am not a scientist. Most of what I know about the theory of evolution, Darwin, and so on, comes from a lifetime of reading and study, most of it during the last 30 years.
What follows represents my understanding of these matters. Ive been as accurate and as careful as I know how to be, but I make no claim of expertise in this area and expect no one to take my word for anything. My hope is that what I have to say will pique your interest and cause you to launch your own investigation. Toward that end Ive assembled a small sampling of books and web sites that may prove helpful to you in undertaking such a study.
Im going to begin by talking about what it was that Darwin was right aboutand some of the things he got wrong. Then Ill discuss why modern biology thinks he was right. Finally, Ill say a few words about why it matters.
I. Darwins idea
Darwins idea was not about cosmology or the origins of life. He offered no cosmological theories and did very little speculation about how life began. His theory took lifes beginning as a given and went from there. Theories about the origins of life are called abiogenesis. Attacks on Darwins theory that raise either cosmological objections or questions about how life began are not valid. Certainly, these are legitimate areas of inquiry, but they have nothing to do with Darwin or his theory.
Darwins idea wasnt about theology. He did not set out to prove or disprove anything about the existence of a deity. While there is no question his discoveries had implications for religionhis own awareness of those implications was one of the factors that led him to hold back on the release of his idea to the general public, it does not follow that Darwin disproved God or attacked religion.
It also wasnt evolution. The idea that life had evolved had been around long before Darwin. In fact he began the second edition of The Origin of Species with a recapitulation of thinking on the subject prior to the publication of the first edition of his own work. In that brief historical sketch, he noted the theories of Lamarck and others, including his own grandfather, Erasmus Darwin, who thought living organisms had evolved but had described no satisfactory mechanism for such change.
Darwin would correct that deficiency with a brilliant insightone that he shared with another naturalist, Alfred Russel Wallace, who had independently reached the same conclusion at about the same time.
Certainly, Darwins idea did not appear in a vacuum. He did not suddenly shout eureka and announce his discovery to the world. It was an ideaor more properly, a collection of connected ideasconceived in a cultural milieu that had a strong influence on his thinking.
One of the books Darwin had read while voyaging on the H.M.S. Beagle was Sir Charles Lyells Principles of Geology. Lyells workbuilding on that of the pioneering Scottish geologist James Huttonput forth the thesis that the very same processes at work shaping the earths surface today had always been at work and accounted for the features of the geological landscape. Among other things, this idea, which came to be called uniformitarianism, suggested the earth was much older than was commonly supposed at the time.
Darwins observations while on the Beaglea voyage which took the better part of five yearswould spark his interest in the subject that would occupy him for the rest of his life: how to account for the tremendous diversity of living organisms and the differences between those which were alive today and those that had populated the earth in ages past. Was it simply the creation of a deity with an inordinate fondness for beatlesas the biologist JBS Haldane is said to have remarkedor was there some natural principle at work?
After returning to England, Darwin supplemented the many observations he already had made with a study of domestic animal breeding and plant propagation. That each species had tremendous potential for variation was evident from the results that could be seen in those efforts. The farmer or dog breeder or horticulturist achieved those results by selectively breeding the individuals most likely to produce offspring with the desired characteristics.
All of this, combined with observations and experiments carried out, first, in London and later at his workshop/laboratory at Down House, where he and his wife, Emma, lived and raised their family, convinced Darwin of the tremendous potential for variation among living organisms and the mutability of species.
Another influence on Darwins thinking was Thomas Malthus 1798 work, An Essay on the Principle of Population. Malthus had suggested that population increases geometrically while available food supplies increase arithmetically. Consequently, populations, left to their own devices would be constantly outstripping their resources. In human history, the agents of war, famine and pestilence had been most responsible for keeping populations in check in the struggle to live.
Darwin knew the same struggle occurred in the other species as well. He had marveled at natures profligacy. All organisms were engaged in a constant effort to sustain themselves. There was competition for available resources and there were many casualties along the way.
Essentially, what philosopher Daniel Dennett calls, Darwins dangerous idea requires three things: a reproducing population, variation among the individuals in that population, and time. What inevitably will happen, Darwin saw, is that those individuals with variations that give them any sort of edge in the struggle to survive will be more successful in living and reproducing themselves, therefore passing on the traits that made them successful to their progeny. Those that were not so favored would be less successful.
Darwin summarized his idea this way:
If under changing conditions of life organic beings present individual differences in almost every part of their structure, and this cannot be disputed; if there be, owing to their geometrical rate of increase, a severe struggle for life at some age, season, or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of life, causing an infinite diversity in structure, constitution and habits, to be advantageous to them, it would be a most extraordinary fact if no variations had ever occurred useful to each beings own welfare, in the same manner as so many variations have occurred useful to man. But if variations useful to any organic being ever do occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance, these will tend to produce offspring similarly characterized. This principle of preservation, I have called, for the sake of brevity, Natural Selection. (Origin of Species, page 107)
Just as humans selectively bred species of plants and animals to produce variations that would satisfy their requirements, Darwin theorized, so conditions in nature favored those variations that gave individual organisms an advantage in the struggle to live and reproduce.
In Darwins Dangerous Idea, Dennett calls natural selection an algorithm, a term he borrows from computer programming. An algorithm is a process that is mindless and automatic. And if the necessary conditions are met, the algorithm always works.
Heres what evolutionary biologist Douglas J. Futuyma has to say:
"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions."
Evolutionary Biology, Sinauer Associates 1986
The process of adaptive modification of populations over time applies to all organisms. The evidence for it is indisputable. Even the folks in the Creation Science, or Intelligent Design, movement concede that such evolution occurs. They call it microevolution.
Its macroevolution that never happens, they say. You never see one species turning into another.
And they are right. You dont. One of the most common misconceptions about evolution is the idea of one species turning into another species. What really happens is descent through adaptive modification over time. Some populations prosper, others dont. Over time, as populations become isolated from one another, the process continues until different species emerge. But at no point in that process can we point to a parent or set of parents that belongs to one species but produces offspring that belong to another.
Stripped of all the terminology, evolution is simply change over time and the process that appears to direct it, in the biological realm at least, is natural selection, Darwins idea.
Darwin also thought all organisms were related and shared a common ancestry. He noted that once some species had begun to reproduce sexually, sexual selection became an important part of natural selection and accounted for a considerable amount of diversity. All of these were part of the matrix of ideas that would come to be called the theory of evolution.
But at its core was the idea of natural selection.
What Darwin could give no satisfactory account of was the source of the variations that made natural selection possible.
Like most of the biologists of his day, Darwin thought each parent contributed characteristics to their offspring and those characteristics were blended in following generations. He wrote of pangenes and even proposed, halfheartedly at best, a theory called pangenesis. The problem with this approach, of course, was that if characteristics blended from generation to generation, then the potential for variation would be diminished rather than increased.
Unbeknownst to Darwin, experiments in plant hybridization being conducted by an Austrian monk named Gregor Mendel would ultimately supply the answer to the weakness in the British naturalists theory.
In Asimovs Biographical Encyclopedia of Science and Technology (Second Revised Edition, published by Doubleday & Company, 1982), Isaac Asimov writes, Darwins theory of evolution by natural selection had one overwhelming weakness. Darwin envisioned natural variations arising in each generation of a species, and natural selection seizing upon those variations to preserve the good and doom the bad. But the action of natural selection was slow and if, in the meantime, through unrestricted and random mating, the varying characteristics melted into intermediacy, upon what would natural selection exert its effect. Mendels discovery that varying characteristics did not blend but remained distinct showed that natural selection could work slowly and still effectively upon natural variation. Mendel might have noted this, for he had read Darwins Origin of Species and was even interested enough to annotate his copy. Nevertheless, when the time came for him to write up his experiments, he never mentioned Darwin. (p 418-19)
According to The Encyclopedia of Evolution: Humanitys Search for Its Origins by Richard Milner (published by Facts on File, 1990), Mendels experiments in plant hybridization lasted about 15 years, ending after he was appointed abbot of the monastery in which he lived and worked. He was 46 at the time. After his death in 1884, his successor had Mendels experimental garden destroyed and all his notebooks, papers and scientific records burned.
Milner writes, Mendels only claim on the worlds attention was the single published paper of 1865 in an obscure journal of natural history, which had remained unknown during his lifetime.
Mendels Laws were not explicitly stated in that paper but were read into his work by his rediscoverers, Milner states. Nonetheless his groundbreaking work with the hybridization of peas and the transmission of inherited traits are regarded as key insights in the development of modern genetic theories.
In a sense, Darwins theory of natural selection was a bit like Alfred Wegeners theory of continental drift. Like Darwin, Wegener had studied huge amounts of evidence from around the world before coming to the startling conclusion that all the worlds continents once were joined together and had been drifting apart for the past 225 million years. Wegeners idea needed the modern science of plate tectonics, however, to explain the mechanism by which the drift occurred. The validity of Wegeners theory is now accepted by modern geology.
Although receiving considerablethough by no means universalsupport from the scientific community of his day, Darwins ideas seemed to languish during the the first part of the 1900s until the synthesis of evolutionary theory and genetic theory, which occurred in the mid-1930s. Today evolutionary theory is the cornerstone of biology and the fact of evolution through natural selection has been demonstrated in countless experiments and observations in virtually every scientific discipline that is remotely related to it.
II. Why we think Darwin was right
At the time Darwin was writing and publishing his works on evolution through natural selection, there was so much we didnt know. The age of the earth was estimated by Lord Kelvin in 1897 to be from 20-40 million yearsfar too short a time for either Lyells uniformitarianism or Darwins natural selection to work. At that time we knew nothing of genetics. Indeed, the word hadnt been invented yet. DNA and RNA wouldnt be discovered until we had gotten halfway through the next century. We knew nothing of radiation, of nuclear fission or fusion. We had no idea of the great revolution in physics that was just around the corner with the development of quantum mechanics and Einsteins theories.
Given the state of our knowledge in the 19th century, its not at all surprising that Darwin got some things wrong. Whats remarkable is that both his theory of common descent and his theory of natural selection, which were his two major contributions, have not only been sustained by what we have learned in the intervening years, but have been strengthened by those discoveries.
Writing in The Ancestors Tale, Richard Dawkins states, We can be very sure there really is a single concestor of all surviving life forms on this planet. The evidence is that all that have ever been examined share (exactly in most cases, almost exactly in all the rest) the same genetic code; and the genetic code is too detailed, in arbitrary aspects of its complexity, to have been invented twice. (p.7)
I should pause here to note that the word concestor refers to common ancestor. One of Dawkins associates suggested the word and he uses it throughout his book.
The idea of common ancestry also receives support from a startling experiment performed by Professor Walter Gehring of the University of Basel in Switzerland. He and his team of researchers identified a gene in fruit flies called eyeless - because if it mutated or wasnt present, the fruit fly would be eyeless. They were aware of the same gene in a mouse which, if you removed both copies of the gene and replaced them with a mutated gene, would render the mouse eyeless.
Gehring states, in a PBS interview available on the web, that the same gene exists in all animal groups from humans to flatworms. He thought it was a master control gene that switched on the genes controlling eye development in a given species.
You have to think, he says, that there are some 2,000 genes involved in making a fruit fly eye, and probably a similar number of genes to make a human eye. And so it came as a surprise that a single gene could block eye development completelyboth in the fruit fly and in humans. This was the same gene.
Now comes the startling experiment.
To test whether this really was a master control gene, Gehrings team took the gene from a mouse and put it into a fruit fly embryo. The mouse gene worked perfectly well and induced a compound eye in the fruit fly. A compound eye! Not a mouse eye but a fruit fly eye.
In a later experiment, they took the fruit fly gene and put it in a frog. This time, the gene induced a frog eye.
Biologists now theorize there may well be a genetic tool box, a small collection of master control genes that are charged with switching on the genetic programs for various major body parts, like eyes, and are common to all animal species, which suggests they would have evolved very early on in the process.
Going to the dogs
I want to return for a moment to one of the areas that Darwin researched in his investigations. Domesticated animals. Specifically, domesticated wolves.
No Im not talking about someone who is raising a wolf from the wild. Im talking about Fido, Mans best friend, one of the first animals that actually came and lived with us.
We now know that all dogs, from the miniature dachshund to the St. Bernard, from the Russian wolfhound to the Mexican hairless, are descended from gray wolves. On average, the genetic differences between gray wolves and your family pet only amount to about 2/10ths of one percent.
Now if you think about that, and then consider that virtually all of the breeds of dogs on the planet today came from that beginning, and consider that the overwhelming majority of those breeds have developed over a very short period of time, you should begin to appreciate the tremendous diversity possible in any species.
In 1959, Russian geneticist Dmitry K. Belyaev began an experiment in which he took captive silver foxes and and began breeding them for tameness. Within about 20 years, Belyaev and his colleagues had produced foxes that behaved like border collies.
Referring to the experiment, Dawkins writes, Less expected were the byproducts of selection for tameness. These genetically tamed foxes not only behaved like collies, they looked like collies. They grew black-and-white coats, with white face patches and muzzles. Instead of the characteristic pricked ears of a wild fox, they developed lovable floppy ears. Their reproductive hormone balance changed, and they assumed the habit of breeding all year round instead of in a breeding season. Probably associated with their lowered aggression, they were found to contain higher levels of the neurally active chemical seratonin. It took only 20 years to turn foxes into dogs by artificial selection. (Dawkins, The Ancestors Tale, p. 29-30)
One of the predictable outcomes of Darwins theory is that we would expect members of closely related species to have a similar genetic makeup. As we have been able to isolate various genomes and analyze the biochemistry of plants and animals, including human animals, we have found that to be the case. There is very little genetic difference between human beings and chimpanzees, our closest kin. Human DNA is much more similar to that of the great apes than is their DNA to monkeys.
None of this suggests there are no disagreements among scientists about various aspects of evolutionary theory. Darwins critics always conflate such disagreements into tales of a theory in crisis. The truth of the matter is that while scientists are always challenging the prevailing wisdom and one another and while there may be disagreements about just how natural selection works, there is virtually no disagreement among scientists that it does work. That opinion is shared by the overwhelming majority of scientists and is nearly unanimous among those working in the biological sciences.
One of the best summations of the state of our knowledge (even though its a bit dated) is the following:
The great age of the earth is a fact. The drift of continents is a fact. It is a fact that the earth has supported different species at different times. It is a fact that beneficial mutations alter species in every imaginable way. It is a fact that the environment selects some genetic variations for survival and others for extinction. It is a theory that the processes of mutation, recombination, genetic drift, natural selection, and isolation can account for the historical products of evolution, but it is a fact that evolution has occurred. That is the message of the one hundred years of biology, geology, physics and chemistry that have elapsed since Darwins death. (Futuyma, Science on Trial: The Case for Evolution, p. 207)
III. Why it matters
I have made the point many times and will make it again here that there really is no scientific controversy over evolution or Darwins theory of evolution by natural selection.
There is a public-relations controversy, to be sure. There is a political controversy as politicians scramble to curry favor with voters by playing to what they perceive to be the voters religious predilections. There is a media controversy as various outlets do stories that suggest the latest iteration of the Creation Science movement, Intelligent Design, stands on equal footing with other explanations of how life developed.
So there clearly is a controversy. It just isnt a scientific controversy.
At the beginning of this I said after the publication of The Origin of Species, neither science nor religion would ever be the same. Certainly, Darwins impact on science can hardly be disputed.
During his lifetime, Darwin published 17 books in 21 volumes containing more than 9,000 pages. Another 1,000 pages appeared in various monographs and articles written for scientific journals. In addition there were almost 10,000 additional pages of revisions added to the various editions of his works over 43 years. Darwin made wide-ranging contributions of new knowledge to geology, botany, animal behavior, reproductive biology and dozens of other fields.
His theories have had far-reaching implications in many disciplines, a remarkable achievement considering that he suffered from chronic illness for most of his adult life.
Dennett offers the following assessment of Darwins idea, Let me lay my cards on the table. If I were to give an award for the single best idea anyone has ever had, Id give it to Darwin, ahead of Newton and Einstein and everyone else. In a single stroke, the idea of evolution by natural selection unites the realm of life, meaning and purpose with the realm of space and time, cause and effect, mechanism and physical law. But it is not just a wonderful scientific idea. It is a dangerous idea. (Darwins Dangerous Idea, p. 21)
Why dangerous? Because it challenges some of our most cherished assumptions.
One of the assumptions Darwin challenged was the notion of a divine order of things, a great ladder of being, on which each rung was occupied by a species that had been created by God and at the top of which was the human species, who had been given dominion over all the rest.
What religionists object to is not that Darwin ruled God out, because he didnt do that. What religionists object to is that Darwin didnt rule God in.
And thats what the attack on evolutionary theory by the Intelligent Design crowd is really about. Its not about the science at all. Its about the existence of a theory that can explain the development of life on this planet without reference to a deity. The whole mission of the Discovery Institute, which provides the funding and the public relations resources for much of the ID movement is to discredit the idea of science as it is practiced today and to substitute the sort of science that existed back in the days when science had to first seek the approval of the church and scientists who challenged the religious interpretation of reality might have their work suppressed and, in some cases, their lives ended.
Left to their own devices, scientists, for the most part, seek no quarrel with religion. Indeed, many scientists believe in a god and some are themselves profoundly religious. However, science which must first conform to the religious views of any group, regardless of what those views may be, is no longer functioning as science. It is religious propaganda.
Consider the words of biologist Kenneth Miller:
In fact, the human genome is littered with pseudogenes, gene fragments, orphaned genes, junk DNA, and so many repeated copies of pointless DNA sequences that it cannot be attributed to anything that resembles intelligent design. If the DNA of a human being or any other organism resembled a carefully constructed computer program, with neatly arranged and logically structured modules, each written to fulfill a specific function, the evidence of intelligent design would be overwhelming. In fact the genome resembles nothing so much as a hodgepodge of borrowed, copied, mutated, and discarded sequences and commands that has been cobbled together by millions of years of trial and error against the relentless test of survival. It works, and it works brilliantly; not because of intelligent design, but because of the great blind power of natural selection to innovate, to test, and to discard what fails in favor of what succeeds. The organisms that remain alive today, ourselves included, are evolutions great successes.
Quoted in Mark Perakhs Unintelligent Design, from an article Lifes Grand Design, Technology Review 97, no. 2 (1994): 28-29, by Kenneth R. Miller
I should pause to tell you that Miller is a believing Christian and the author of Finding Darwins God. If you are interested, you can go visit his web site and read other articles defending a theistic interpretation of Darwins theory. But Miller is also a scientist of some repute, and he sees no case for Intelligent Design theory at all.
This matters because at this juncture in human history, at a time when our society needs scientifically literate, technologically sophisticated adults, many school districts and politicians are kowtowing to the religious right and undermining our childrens science educations. We, as a nation and as a society, will be the poorer for it.
But there are other, more positive reasons, why Darwins theory matters.
It speaks to us of the connectedness of all life. It affirms our place in the universe and on our home planet. It demonstrates with elegant simplicity that we are, indeed, a part of nature, not apart from it.
When I hear someone say, But that means were just animals, I can only smile to myself.
Indeed we are, I cant help thinking, and what a marvelous thing that is to be.
What Ive tried to explore in this brief talk is what Darwin had to say, why we think he was right to say it, and why it matters today. I have tried to illustrate the importance of Darwins theory, then and now.
So does that mean, debate is ended, and we now should say Darwin has the last word. Not at all. One of the significant things about science is that no one ever gets the last word. Science is a work in progress. Like the marvelous animals who do science, it too evolves.
Its entirely conceivable that someone will come up with a better idea than Darwins some day. But if they do, it wont be because they exploited uncertainties and genuine questions in order to plug their theology in to the holes in our knowledge.
Saying this is so complex it must have been created by a god or the odds against this happening as part of an undirected natural process are too great are not scientific theories. It is fundamentally dishonest to mislabel uncertainty as God and then claim one has found an answer to unanswered questions.
I dont know is always a perfectly acceptable answer to such questions. Lets find out is an even better one.
© 2006 by George A. Ricker
On the web:
BBC Evolution Weekend: Darwin - the Man and His Legacy
Lots of information about Darwin and his theory.
Charles Darwin Works
Darwins works, including The Origin of Species, online for reading. Theres no charge for this site.
Evolution: Darwin: An Origin of Species
A survey of the theory. Lots of good information about modern thinking about evolution.
Ken Millers Evolution Page
A theist talks about evolution and the Intelligent Design movement.
The Panda's Thumb
Commentary on evolution and Intelligent Design.
Talk Origins Archive: Exploring the Creation/Evolution Controversy
The title is self-explanatory. A huge archive with lots of information. Also many links to other sites, including those who take the other side in the argument.
An explanation of how evolution works. Intended for teachers, its also useful to anyone who really wants to understand the theory.
In the library:
Dawkins, Richard. The Ancestors Tale. New York, Houghton Mifflin Company, 2004
The story of human evolution told in reverse, with lots of interesting side trips along the way. If you want a one-volume summation of what modern evolutionary biology has to say, look no further.
Dennett, Daniel C. Darwins Dangerous Idea. New York, Simon & Shuster Paperbacks, 1995.
A discussion of the implications of evolution through natural selection in biology and beyond.
Futuyma, Douglas. Science on Trial: The Case for Evolution. New York, Pantheon Books, 1983.
Written in response to the Creation Science crowd, much of the material here also counters claims made by the advocates of Intelligent Design.
Milner, Richard. The Encyclopedia of Evolution. New York, Facts on File, 1990.
Lots of general information about evolutionary theory.
Perakh, Mark. Unintelligent Design. Amherst, NY: Prometheus Books, 2004.
A critique of Intelligent Design that analyzes the claims of Behe, Dembski, Johnson, et. al.
Stebbins, G. Ledyard. Darwin to DNA, Molecules to Humanity. San Francisco, CA, W. H. Freeman and Company, 1982.
A discussion of the history of evolutionary theory with particular emphasis on the synthesis of natural selection and genetics.