Posted by
Doc Stephens on Sunday, February 17, 2008 7:08:00 PM
Don't expect me to answer the question precisely, because the classification of living things into species is somewhat arbitrary and mostly for the convenience of scientists. I'll come back to this very basic question, but first, for some context, please read my previous post.
At the most recent local school board meeting, several scientists and science educators, along with one local minister, addressed the board. After listening and asking some questions, the board took no action. It did not approve the proposed resolution which argued for the inclusion of "alternative theories" to the Theory of Evolution and also to the Big-Bang Theory in the new Sunshine State Science Standards.
Not surprisingly, the debate goes on. Ever since the recent meeting, there have been several letters to the editor. There are multiple arguments going on among people who don't understand each other. If it weren't so sad, it would be funny. If it didn't make my head spin, I'd just cry, or laugh, and go on with my day. Writing this blog is my way of stopping my head from spinning. Today's offering was from a well meaning chap who stated in his letter to the editor that he was
sorely disappointed when reading that the Highlands County School Board had backed down after listening to a few speeches by people who were claiming that evolution is a proven scientific fact, and that any other theory had no right to a discussion in science classes!
He then went on to provide three criteria for accepting a scientific theory:
It must be observable, it must be reproducible, and it must be predictable.
He then concluded with this.
If evolution had those three characteristics, perhaps we could accept it as a viable explanation for what we see all around us; the astonishing complexity of life, the world and the universe.
It is my belief that evolution in fact does not exhibit even one of those criteria:
1. Show me a species which is observably changing into a new species.
2. Show me that you can reproduce the change of a species into a brand new and entirely different species.
3. Predict for me what the next new species is going to be like.
In reference to number three, it appears that mankind is at the top of the heap at the present time. What are we going to develop next? Will it be a living, breathing, thinking, speaking, all-knowing, all powerful, immortal race worthy of the best of present science fiction? Would we then call him God?
Let us evaluate your prediction.
If evolution cannot answer these questions, what would be the harm of allowing our young people to consider other possible explanations of our present existence, such as Intelligent Design, or even creation? What are you afraid of?
The author of this letter is surely intelligent and learned about many things, but his letter is illustrative of the lack of scientific literacy among many in our modern society. Scientists have their own jargon. So do people in almost every walk-of-life. Have you listened to nurses talk to each other? How about trying to decipher a conversation amongst a group of insurance experts, or computer geeks, or engineers, or fisherman, or carpenters, or sailors?
Well, scientists, in every field of science, assign their own meanings to the words they use. In some cases they use words that also have different meanings in common usage by non-scientists. So, when scientists get into arguments with non-scientists about scientific ideas, we have a mess. That is what we have here, a mess! As my good friend Chuck Dillon says: "It's goofy."
Let me analyze this, one point at a time.
The gentleman from Avon Park, the author of the letter-to-the-editor in today's paper, did not attend the school board meeting and did not hear the "speeches" that he referenced and characterized. Right away, you know he's going to be in serious trouble because he's relying on what he read in the newspaper--don't get me started on that subject--or on what he was told by someone else, or most likely, by what he assumed. In fact, none of the speakers at the school board meeting opined "that evolution is a proven scientific fact." They know that the Theory of Evolution is a scientific theory, and that theories and facts are not the same. Furthermore, they know that scientific theories are never "proven" and can never be "proven" because science seeks to understand and explain, but cannot prove. To "prove" a theory, you would have to conduct every experiment, infinitely many times, and answer every possible question related to the theory--let me know when you're finished.
Proofs are very helpful in mathematics. Proof is important in a court of law. We often look at proofs before approving a portrait, or a book to be printed or published. In science, it is impossible to finally and conclusively prove a theory, and if anyone argues otherwise, they are arguing from the perspective of someone outside of the realm of, and the jargon of, science--way, way, way, outside! A "proven" theory would be dogma, and science abhors dogma! Nevertheless, I know many scientists who would claim that a particular theory has been proven--they are flat wrong. A theory may be very well established, very well supported, or without inconsistent observational evidence, but that does not warrant the claim of proof. Science seeks the truth, always and objectively, but science can never know if truth has been discovered.
One of the most important agreements within the philosophy of science, is that theories can, and should always be tested and questioned. A disciplined scientist never gets too attached to a theory--they should always remain skeptical. Theories may be supported, or not, by observations and experimentation. It is the results of scientific experiments that need to be reproducible, not the theories. (The assertion, by the author of the letter, that theories need to be reproducible, is illogical nonsense). You don't repeat a theory, you test it, and then you test it again and again. If you get consistent results with each repetition of the experiment, then the theory is still supported. If the results are not reproducible, then, either the experimental procedure was flawed, or the theory is incomplete. You test theories through rigorous peer evaluated research, one type of which is experimentation, but there are other equally important types of scientific investigation.
Not all observation is direct. It is impossible to directly observe an atom or an electron because of their extremely small size and the limitations of our eyesight, but these very small atoms and electrons are commonly observed indirectly. It is difficult to directly observe the formation of a mountain range such as the Himalayas because the geological processes involved in plate tectonics are exceedingly slow. It is easy to observe such geological processes indirectly. Not all observations are direct.
Is a scientific theory "predictable"? The gentleman's grammar is, once again, confusing, or wrong. In science we would expect that a "good" theory would reliably predict or explain certain outcomes of experiments. It is the observations or results that are predictable, not the theories.
Very often, models are developed to test and refine the validity and reliability of theories. Many of the models used by scientists are mathematical, but others are not. Einstein, was famous for his "thought experiments" which were often visual models we could imagine in our minds eye to help us to understand and explain certain observations or outcomes. There are computer simulation models of climate change, for example, which attempt to predict future climate change. There are models of the rates of mutation in DNA that attempt to establish the probability of future mutations, or to estimate how long it might have taken for certain changes in archaic DNA to have evolved to their presently observed state. Any model that fails to predict a certain outcome is either an incomplete or inaccurate model, or the theory warrants refining. All scientific theories are open to question and continuous improvement.
Now, please allow me to address the gentleman's "belief" that evolution does not meet the tests of observability, reproducibility, and predictability. He apparently does not "believe" it, and that I cannot question. He is entitled to his "beliefs" as am I.
Can we observe evolution? Certainly we can. Archaeologists observe evolution, microbiologists observe evolution, entomologists observe evolution, ornithologists observe evolution, pet owners observe evolution, unfortunate souls who have HIV Aids or Bird Flu observe evolution. all of these, and infinitely more, are observations of the process of evolution. They are not observing the Theory of Evolution, but that theory would explain and predict what they observe. We observe that none of the native species of monkeys (there's that word) in Africa have prehensile tails, but monkeys in South America do. We observe that more than 95% of the DNA of a chimpanzee is the same as the DNA of modern humans. We observe that fossils of primates have characteristics that are in common with modern humans and modern great apes. We are observing evolution, the process, as it is explained by the Theory of Evolution.
Microbiologists have the luxury of working with organisms that evolve rapidly, and they can create new species in a matter of hours or days. The common domesticated dog and the modern wolf both evolved from archaic creatures over the course of human history and pre-history. Modern dogs and wolves are now separate species, but they had a common ancestor--at least all of the evidence collected so far supports that hypothesis, and no credible evidence contradicts it. Anthropologists hypothesize that dogs and humans coevolved (evolved together) because of the influence that each species had on the other. Our human night vision is not nearly as good as a dog's, neither is our sense of smell or the frequency range of our hearing. Our ancestors relied on dogs for security and hunting, particularly at night, and the dogs relied on us for food and protection from other predators, especially during the day. The dog's color vision in not nearly as good as ours. When compared with DNA extracted from modern wolves and dogs, we can see genetic differences that can be explained by their different evolutionary histories. All domesticated plants and animals have evolved as a result of human intervention and we have historical records to document the evolutionary development of these living things. Try to find a wild milk cow running around anywhere on Earth. The modern milk cow would not survive without humans. You won't find modern corn, wheat, or rice growing wild either. These plants would not grow without human planting and harvesting.
Is evolution reproducible and predictable? Very! A Geneticist can tell you precisely what will happen if you change a certain base pair in the gene that maps the amino acid sequence of the polypeptide insulin. they can change that base pair and observe the predicted result. Individuals who suffer this variation will have a type of diabetes. The theory of evolution explains how species evolve through genetic drift, natural selection, and gene flow. The theory explains how changes in an environment can select for different genotypes, and it can predict which will survive and which will become extinct because of an inability to adapt. Scientists can artificially create mutations and observe the results, over and over again without exception.
Now I'll respond to the author's three challenges.
1) "Show me a species that is observably changing into a new species." The best response would be that every species is observably changing into a new species, but the observations are mostly indirect because the changes are subtle and very slow for large multicelluar organism. The letter writer asked for one example. The European Honey Bee in North and South America is evolving into a new species as it interbreeds with the African Honey Bees introduced into this hemisphere.
2) You can change one species of bacteria into a new species by selectively changing it's environment, perhaps its food source, the temperature, the pressure, etc., and then isolating the succeeding generations which show adaptive characteristics to the new environment. After several generations, you would have two or more new species. This same process happens on a much slower scale with eukaryotic and multicellular organism. The horse and the zebra are different species, but they have a common ancestor. The chimpanzee and the orangutan are different species but they have a common ancestor. The bluebird and the rattlesnake are different species but they have a common ancestor, etc.
3) I can't predict what "the next species" will be like because our theories are not good enough for this kind of prediction. We can't predict how the Earth will change, how climate will change, how the land will change with any degree of certainty. We can't yet know how the sun will change, whether our planet will be struck by a giant meteorite, or if an immense supervolcano will erupt and cause a mass extinction of many, or even most species currently living on our planet. We know that such mass extinctions have occurred in the past. I cannot predict which living things would survive, because I do not know how the planet would change. I'd place a good bet that humans will survive, and continue to adapt to a new environment, because I "believe" that God gave us intelligence to understand these things. I believe that "God" wants us to understand so that we have a better chance of adapting, evolving, and surviving. But these are my "beliefs" not theories, and certainly not scientific theories.
So what is a species. Species are groups of living things that share genetic traits as defined by scientists. Various criteria are used, but the definition of species has changed and the criteria have changed. Scientists find it convenient to classify living organism into these categories. The classification system includes many levels of categories including: species, genera, families, orders, classes, phyla, kingdoms, and domains. Within these major hierarchical levels there are sub-levels and variations. It is incredibly complex. The distinctions and similarities between different species are hotly contested between experts in each field of biology. Organisms often are reassigned or reclassified as differenct species as new evidence is found, and as some scientists hold greater influence over others. Even within our own species Homo sapiens, (Latin for wise man) the debate over whether to include neandertalensis continues unresolved--is it the same species as us, or not?
There is no harm, whatsoever, in allowing young people to explore other "theories" such as Intelligent Design, and Creation. I hope young people are studying these ideas and perhaps even "believing" them. They just aren't scientific theories and most science teachers are not qualified to teach them. They belong in humanities, or literature, or history, or cultural anthropology, or comparative religion, but not science. Science cannot answer the question of whether some "intelligence" created the universe as it is, all in one moment, or over 13.5 billion years. It is not a scientific questions, it might be a philosophical question and is most certainly an interesting one. I think about it all the time. But science can only deal with what is observable within our natural and physical realm. Science is much more limited than the humanities and philosophy, or religion and theology.
I'm definitely not afraid of any of these ideas.