When I teach my students about the evidence for species change I am often confronted by parents (and students, teachers, and school board members) who want to influence what students will learn. I know that there are people in my community that view the teaching of species change as a threat to their particular brand of Christianity. They may not always confront me face to face, but recently a certain letter was shared with my wife, the local Presbyterian minister. As a geology minor and physical anthropology major in college, she is well qualified to rebut this letter, but she handed it to me and said something like “Why don’t you deal with this?” The letter begins “As far as scientific evidence that disproves evolution, here are a few science absolutes to consider.” As a science teacher who has a solid faith in the Word of God, I have many questions about this document and what it aims to achieve.
What is the purpose of a letter presenting “scientific evidence” against species change?
Before I discuss the specific arguments in this letter, we should first think about why such a letter exists. The letter is addressed to local ministers and youth pastors and aims to provide scientific evidence that these leaders can use to help defend their members against “the claims of naturalistic Darwinian evolution.” The main goal of the letter is to provide “evidence for the existence and activity of our Creator God.” Furthermore, the author of the letter believes that we should defend the Bible against claims that it is “outdated, inaccurate, unscientific, and out of touch with reality.” The writer ends their letter by offering their services to any congregations or individuals who are interested in “nurturing solid faith in the Word of God.” In short, the letter appears to be an attempt to portray belief in the Bible and perhaps God Himself as completely at odds with current scientific theories of biological evolution.
What is “naturalistic Darwinian evolution” according to the author of this letter?
We should also consider the writer of the letter and their use of the phrase “naturalistic Darwinian evolution.” Clearly this phrase is used to represent a belief system that is contrary to that of the author. Knowing what I know of the author, I’m going to assume that “naturalistic” means “without God” or perhaps even “against God.” “Naturalistic” could also mean “random” or “unguided.” “Darwinian” usually refers to Charles Darwin (not Erasmus) in a way that presents his ideas as some sort of alternative theology that replaces God’s central role in Creation (even though Darwin (both of them) credits a Creator). “Evolution” is probably the stickiest word in this phrase. Does the author refer to the fact that species can change over time? Does the author mean to discuss the Big Bang or the origins of life? Unfortunately, the author’s use of the term “evolution” is used as a stand-in for many separate scientific concepts including biological evolution, the origins of life, and the origins of the universe.
What do biologists really mean by the term “evolution?”
Species can change over time. In Charles Darwin’s famous words evolution is “descent with modification.” This is really the only acceptable answer to the question “what do biologists mean by ‘evolution’?” We are not talking about the origin of life or the origin of the universe. Biologists focus on whether or not species can change and adapt to new environments over time. To say that an organism “evolves” is to say that it may have very different features multiple generations from now than it does in the present time. Those features are defined by the particular genetic makeup of individual organisms and how likely those features are to aid or hinder the survival and reproduction each individual. Collectively, those features (traits) that are successful in certain individuals will be increased in frequency within an entire population of that organism. Over time, accumulated changes may allow one population of organisms to become significantly different from a separate population of that organism, giving rise to an event known as speciation. In short, biologists have observed that species can change over time and give rise to new, distinct species.
What evidence is presented against species change?
The letter that was delivered to local churches presents 8 lines of evidence that are said to disprove evolution. Only 4 of these lines of evidence pertain to biological evolution. Three other arguments are aimed at explaining the act of creating the universe and so do not directly address species change. A fourth argument argues against current hypotheses of the origins of life and also does not address species change.
There is considerable overlap between the 4 arguments against species change so that all the arguments can be summarized in the following two statements:
- Species change is so complicated that you could never understand it, therefore it does not happen the way they say it does.
- New information is required to create new species. There is no new information, therefore no new species can arise.
This letter does not describe any evidence for the hypothesis that species of living organisms cannot change and have not changed since they first appeared upon the Earth, i.e. that species have not evolved. While the arguments presented are therefore only in the negative, they are still worth refuting.
The argument from complexity
One common argument that is often used against modern scientific understandings of phenomena is that Nature is so complex that we could not possibly understand it. The argument from complexity used in this letter appeals to the individual and their experience, knowledge, and their sense of “rightness” of a particular belief. This relies upon the perception that if I don’t experience it or understand how it works, then it does not happen the way that other people describe it. Capital S “Science” in this mindset refers to all the “experts” who have tried to explain the world but have failed or have been wrong multiple times. In the words of the Apostle Paul:
Professing to be wise, they became foolsRomans 1:22
Global climate change is thought by some to be so amazingly complex that we could never understand how humans are affecting the planet. Likewise, there are so many complex biological systems of interacting atoms, molecules, cells, tissues, organs, organ systems, organisms, populations, communities, and ecosystems that some believe that we could not begin to understand how living things work.
But the argument from complexity runs into an unfortunate reality: just because I don’t understand how something works doesn’t mean that no one understands how that system works. In many cases several people have joined together to bounce ideas off of each other through thought and experimentation and have collectively reached conclusions about the most likely mechanisms behind a certain phenomena, for example that diseases are caused by infectious pathogens such as bacteria and viruses. Just because an individual has not personally observed bacteria doesn’t mean that they don’t exist. The existence of bacteria as pathogens is not a matter of faith, but it may have seemed that way at first to the general population when their role in disease was first discovered. The argument that Nature is too complex and that we will never understand whether species change or not does not take into account the fact that many thousands of people have made this study their life’s pursuit for the glory of God through understanding His Creation.
Great are the works of the LORD; they are studied by all who delight in them.Psalm 111:2
The argument about biological information
Let’s be clear from the start that this argument is based on incomplete or false understandings of what DNA is, how it can be changed, and what the results of those changes are. DNA studies in the last few decades provide perhaps the strongest proofs of species change and so have been rightly targeted for dismissal by those who would argue against biological evolution. But do their claims stand up to the evidence?
The most erroneous claim made by the author of this letter is that mutations are “part of the entropy we observe in the genome” and that “mutations are always negative.” The letter goes so far as to say “positive mutations are a myth.” Before fixing those misconceptions, let me first try to understand the views of the author of this letter. I believe that a summary of their ideas might go something like this:
- DNA does exist and it provides information to cells and organisms in a total package called a genome.
- Mutations exist and are changes to the original DNA information.
- DNA is “ridiculously complex” (see the discussion above) and existing genomes could only have come about through Intelligent Design.
- Therefore, any change to the DNA (mutation) is a deviation from the Design and therefore mutations “only mess up already existing information.”
First of all, there is no proof one way or another that God designed each and every genome of every individual creature on the planet. Proof of such intervention is impossible because issues of causation by God are in the realm of belief and not open to scientific investigation. It is possible, however, to believe that God uses mutation of DNA as a mechanism of Creation of new species, but again, this is a belief, not a statement of scientific fact.
It is a scientific fact, however, that DNA can easily be changed, even over the lifetime of an individual organism or indeed individual cells. Our modern understanding of cancer biology is built upon the foundation that environmental damage to DNA can cause changes in the information found in certain cells that cause them to divide inappropriately. Cancer biology is certainly an area where the author of the letter and I will agree that DNA information can be “messed up.”
But what about DNA changes from generation to generation? Does the author of the letter mean to say that since we are different from our parents we therefore are less human, as we have inherited some slight differences in our DNA from that of their parents (although most differences are the result of recombination of the parental genes)? Are Adam and Eve the only true humans and everyone since has somehow polluted the original DNA? What about people of different races? Whose DNA is the stuff that God designed? I’m pretty sure I don’t like where that line of argument will end up.
Let’s instead look at a case where mutations have been documented in humans, and beneficial ones at that. Can you drink milk? Or are you lactose-intolerant? Technically, the term should be lactase-persistent because nearly every human can drink milk as an infant. So why can some people drink milk as an adult and others can’t? A mutation. Studies have shown that multiple human populations who live in close proximity to dairy animals have independently developed mutations that allow milk to be digested as a major source of nutrition. Current estimates are that only about 35% of adult humans on the planet carry this type of mutation. Is this ability to drink milk “new information?” Are these 35% of humans a new species or are they a polluted offshoot of the true human line? The author of the letter makes a bizarre statement that relates to beneficial mutations like these that reads as follows:
“There are a small percentage of mutations that are admittingly “beneficial”, but not “positive”. Beneficial in that loosing, an enzyme, or trait occasionally adds to the fitness of the organism, but it is technically a loss of information, not a gain, therefore not a “positive” mutation (one that adds new information to the code). Positive mutations are a myth. Mutations are always negative.”-from the letter to pastors
It will help the conversation at this point if we examine what the DNA code is and what might constitute “new information.” As the letter reminds us, DNA is made of 4 digits, called bases, that come in the flavors of A, T, G, and C, to use their symbolic abbreviations. These 4 bases are joined together in a linear sequence of bases that run up and down the middle of a molecule that looks like a twisted staircase, the famous double-helix. It is the order, or sequence, of bases in DNA that provides the information to each cell as to how to build correct proteins for each job that needs to be done. Each three bases in a row create what is known as a codon that codes for which amino acid needs to be inserted into a new protein. For example, the DNA sequence that reads CACGTGAAATGT might look like so much nonsense to us, but a cell at work will use it to build a protein that begins with Histidine-Valine-Lysine-Cysteine amino acids in that order.
What then constitutes “new information?” Since the sequence of bases in DNA directly determines the order of amino acids in the resulting protein, a change (mutation) in the sequence of bases results in a change in the information used to build a protein. Therefore, every mutation is new information. Does every mutation change the DNA information in a meaningful way? No. Some mutations are silent due to the fact that some changes (like CCT to CCG) result in no difference to the protein produced (both code for Proline). Some mutations are quite noticeable however, especially if the chemistry of the protein produced causes it to take on a wildly different shape in its finished form. Such changes have been observed in regulatory proteins that control when lactase enzyme is produced and also in diseases such as cystic fibrosis and sickle cell anemia.
This discussion hasn’t even scratched the surface of how the information in DNA can be changed via massive interventions from viruses and chromosomal rearrangements and duplication. Single base changes (point mutations) are not the only major changes happening to the information stored in DNA. And what if all of these changes occur in cells of the germ line that are used to make new babies? Those babies will be different than their parents. Through multiple generations over time with accumulating changes to the information in DNA eventually there will come a point at which the resulting proteins function so differently in vastly different combinations than before that the resulting organism is different enough from its original ancestors as to be considered a member of a new species.
What if species really do change?
What happens when my students study biology and find that the massive weight of evidence from astronomy, geology, fossils, comparative anatomy, vestigial structures, embryology, DNA, and biochemistry indicates that the earth has changed in measurable ways and that all life has changed over billions of years along with the changing surface of the planet?
The author of this letter and I have the same goal: to bring people to begin to know and understand Jesus Christ and the God of all Creation. I have an additional goal as a science teacher, and that is to encourage students to develop scientific habits of mind. In particular I want students be able to collect and analyze data and, most importantly, I want them to be able to change their minds when presented with new evidence. However, a student’s faith journey and their acquisition of a scientific mindset are usually very disconnected.
A trivial fix would be to never teach “controversial” topics in a biology class, and therefore never expose students to these ideas. That would shield them for the moment from observations that show that species do change over time. This is the approach often taken by home-schooling parents and some teachers at both private and public schools. However, willful, planned ignorance regarding certain scientific observations is contrary to the mission of a science teacher and so that is not an option in my biology courses.
I could do as some suggest and “teach the controversy” or “teach both sides.” Certainly this approach has appealed to some school systems around the country who have tried to legislate the teaching of “Creationist” ideas alongside those of the “Darwinists.” But this is a false equivalence. Only one of these two supposedly antagonistic schools of thought has any scientific data to support its claims, namely that species have changed and continue to change in response to environmental variables. A science classroom should be a place where data is collected and analyzed. Philosophical topics that are not testable such as God the Creator, Jesus the Redeemer, and True Love belong in philosophy or religion classes that are equally valid educational experiences for our students.
When my biology students investigate these issues, they are faced with two scientifically testable possibilities that are mutually exclusive: either species of living organisms can change and have changed over time in response to changing environmental conditions OR species of living organisms cannot change and have not changed since they first appeared upon the Earth. Any other discussion of Who created them or how is outside the realm of scientific inquiry.
How to lose a Christian
The way to destroy belief in Christ and in God the Creator is to convince someone that if they accept that species of living organisms can change and have changed over time then they cannot believe in God, the authority of the Bible, and in the humanity and divinity of Jesus Christ. The most obvious goal of the letter that my wife received is to refute every scientific argument that might support species change. But what if a student sees through some of the fallacies and outright inaccuracies present in these so-called scientific arguments? What if they learn that species do change?
Christians who rely upon anti-evolution arguments to help people believe run the risk of alienating all future students if their arguments are not based in actual science. Anyone who learns the basic facts about how mutations and chromosomal rearrangements occur will raise their eyebrows about an argument that says that all mutations will have negative consequences. If a student studies about the rise of lactase persistence in certain populations they will learn that drinking milk in adulthood is “new information” in terms of human DNA sequences. How many scientific facts will it take to break their faith? Consider the following quote from conservative writer Michael Gerson
Michael Gerson, “The Last Temptation”
“…they (Evangelicals) made a crucial error in picking evolution as a main point of contention with modernity. “The contest between evolution and Christianity is a duel to the death,” William Jennings Bryan argued. “If evolution wins … Christianity goes—not suddenly, of course, but gradually, for the two cannot stand together.” Many people of his background believed this. But their resistance was futile, for one incontrovertible reason: Evolution is a fact. It is objectively true based on overwhelming evidence. By denying this, evangelicals made their entire view of reality suspect. They were insisting, in effect, that the Christian faith requires a flight from reason.”
It would be better by far to encourage students to engage with the scientific community, read peer-reviewed research, analyze data for themselves, and to treat that scientific knowledge gained as a way of understanding God’s Creation. What is taught in Bible Study, Church, Sunday School, and Youth Group should not set students up to have to choose between their faith and an understanding of how God’s Creation works as experienced through their science classes at school.
For a much more thorough discussion of some of the arguments presented above and for inspiration for how to integrate the teaching of science and the practice of faith I will direct you to these texts:
The Language of God: A Scientist Presents Evidence for Belief
Origins: Christian Perspectives on Creation, Evolution, and Intelligent Design