Can Evolution Generate New Information?
We at BioLogos marvel at the complexity of genetic information but agree with the majority of biologists that well-understood processes—which we understand to be under God's providential care—give rise to new information all the time.
Our intuitions can be misleading
DNA is often likened to an instruction manual from which living organisms are built, and many people find it intuitively implausible that an instruction manual could change itself to produce something new. If this intuition is true, it would mean there must be an intervening intelligence to produce new information.
In responding to this, we might first consider that our intuitions are not always a reliable guide to what is possible. It didn’t seem possible to most people before the seventeenth century that Earth is spinning on its axis and orbiting the sun. It still doesn’t seem possible to many people that time slows down the faster you go. And perhaps our intuitions aren’t reliable about what kinds of changes in DNA are possible through natural processes over long periods of time.
God’s role in natural processes
Besides the intuitive implausibility of the natural mechanism, it also seems to many people that if there is a natural or scientific explanation for some event, then God must not have had any active role in bringing it about.
At BioLogos, we affirm that God sometimes acts miraculously to bring about things for which there is no scientific explanation—think of the Resurrection, turning water into wine, or other miracles to which Scripture testifies. But we also affirm that God brings about his desired ends in the natural world through regular and consistent means that science can describe. It is theologically correct to say that God created the Hawaiian Islands and that God knit each of us together in our mothers’ wombs, even though we have detailed scientific descriptions of these processes.
So the question here is whether the generation and development of information in DNA is one of those miraculous events for which there is no possible scientific explanation, or whether it is a regular and consistent process that science can describe. Either way, God is the author of life. We must consider the evidence in the natural world to determine which way God accomplished it.
Origin of life
When we ask whether evolution can generate new information, it is important to be clear on what exactly we mean. The process of evolution acts on already existing organisms, so it should be understood as an explanation for the diversification of life—not as the origin of life. There is active scientific research about the origin of life (a field of study called abiogenesis), and currently no consensus exists among experts on a plausible scientific explanation for the origin of life. Perhaps it was one of those miraculous events for which there can be no scientific explanation, or perhaps scientists will eventually develop a plausible explanation. That is not the focus of concern in this article.
The other term that needs clarification in the question is “information.” It is commonly used in several different ways, and the failure to distinguish these is what often leads to confusion.
There are precise mathematical definitions of information developed for different contexts in various fields of science and technology. One of the best known of these is Shannon Information, which is used to determine the most efficient ways of transmitting data in a communication system. This is incredibly important for making the Internet work, but is not the kind of information in DNA.
The most common use of “information” refers to meaning that is conveyed by a symbolic code of some kind. Ordinary language is a symbolic code in which words have come to stand for specific concepts, and when strung together in particular ways they convey information. The list of scores in the sports section of a newspaper is a symbolic representation of things that happened, and thus conveys information about the past. A recipe uses words and other symbols to convey information about how to cook something. A computer code contains information that has been encoded by the programmers.
The key to understanding this sense of “information” is that the symbols used in natural or programming languages mean something else, and they only mean something else because we have assigned them meaning. That “meaning” is the information, in this sense of the word. It is fair to question whether natural process can generate this kind of information. But that is not the kind of information in DNA.
There is another use of the word “information” and it is this sense of the word that comes into play in the question of whether natural processes can generate new information. In DNA, information means the specific physical states of biomolecules that determine how living organisms function. In this sense we talk about the information in an organism’s DNA. But DNA is not a symbolic code like a language or even a computer code. It is not composed of symbols that mean something else—the As, Ts, Gs, and Cs are the symbols we use to describe its molecular structure. DNA itself is not actually composed of letters! It is a molecule with a specific shape that does something. If the question is whether natural processes can generate new information in this sense (strings of molecules that do something different than had been done before), then the answer is clearly yes.
Examples of new biological information
If information in the genome is understood to be the physical states of the biomolecules, then sexual reproduction produces new information with each new generation. Just look at how children differ from their parents—these changes require new information. New information is also generated any time there is a mutation to the genome as it is passed along from one organism to its offspring. Some of the time those mutations result in information that is harmful to the organism. But other times the mutation will be neutral or even positive, and the new information might positively impact future generations.
To see how mutations can generate new information this way, first recall that DNA is a double-stranded helix, shaped like a spiral staircase (see figure below): the “rails” are made of repeating units of sugar and phosphate, while the “steps” are made of pairs of molecules called bases. There are 4 bases: adenine (A) and thymine (T) always pair together, and guanine (G) and cytosine (C) always pair together. In eukaryotes, the double helix itself folds up around proteins called histones, forming nucleosomes. The nucleosomes are further packaged in a compact arrangement called chromatin, which enables the genetic information to fit within the tiny nucleus of the cell (if it were stretched out the DNA in just one cell would be about 2 meters long!).
Proteins do most of the work in the cell, and their function is tied to their shape. A protein’s shape is dictated by the linear sequence of basic building blocks called amino acids, of which there are 20. A group of 3 DNA bases called a codon leads to the selection and incorporation of a particular amino acid into a particular protein. Thus, the sequence of bases along one strand of the DNA helix ultimately guides the production of all the proteins in our body. (Reality is more complicated, of course; not all DNA codes for proteins.)
So consider this short segment of 9 nucleotides grouped into 3 codons:
ACT | CCT | GAG
The codon ACT selects the amino acid threonine, CCT selects proline, and GAG selects glutamic acid. But if the A in the GAG codon mutates to a T, the resulting GTG codon results in a substitution of the amino acid valine instead of glutamic acid. This one simple change is enough to have a profound effect because this stretch of DNA is a section of our hemoglobin gene, and this specific mutation causes sickle cell anemia. It is called a point mutation (because it affects a single base), and there are numerous examples of these kinds of mutations that change the information state of the DNA—the DNA does something different than it did before. Individuals with only one affected copy of the gene (from one but not both parents) do not develop the disease and are also somewhat protected against malaria—a positive outcome for some members of a population. This example shows that new information—in the form of new states of biomolecules—can arise through natural mechanisms we understand.
Other examples of new DNA information
There can also be mutations in regulatory regions which affect when and where a gene is “turned on” or expressed. A mutation in a regulatory sequence could lead to the protein being produced in a new place, or in greater or lesser amounts than before. A small change in gene regulation can lead to a large effect. Snakes are a nice example; they are classified as tetrapods (four-limbed vertebrates), even though they do not have limbs. The gene that produces a protein important in limb development is still present in snakes’ DNA, but it is no longer expressed, so limbs do not form (though limb buds do).
Another method of developing new information in a genome is by horizontal gene transfer (HGT), which is the exchange of genetic information between individuals of different species (as opposed to vertical transfer from parent to child within a species). It is especially important for bacterial evolution, because bacteria are able to trade genes like baseball cards, and thereby quickly adapt to new situations. For example, bacteria use HGT to acquire resistance to antibiotics.
Other more dramatic changes in the information state of DNA occur when genes, chromosomes, or even whole genomes are duplicated, sometimes leading to novel results. For example, a new crawfish species was formed about 30 years ago when two individuals of a common species mated, and the resulting crawfish had three copies of each chromosome, instead of two. The mutation made it possible for the new species to clone itself (produce asexually). There is good evidence that early vertebrates had two whole genome duplication events in their lineage — the effects of which can be seen in all vertebrates living today, including humans.
Scientists have characterized many other kinds of changes that can take place in an organism’s genome, all of which represent sources of new information. See our extensive blog series (here) for further examples and explanations of new information being generated in DNA.
When people claim that evolution cannot account for the development of new information, they usually have in mind the second definition of information: the kind that depends on humans (or other intelligent beings) assigning meaning to a symbolic code. We don’t know of natural processes that account for that. But that is not the kind of information in DNA. There we find an amazing string of biomolecules that can and does change with every generation. Each time it changes, there is new information in the sense that it causes physiological changes. Much of the time, these changes will be neutral or even harmful to an organism. But sometimes—especially when many changes accumulate over time—innovations arise and gradually even new species can come into being.
Isn’t this process wasteful? Wouldn’t an all-powerful God create things more efficiently and directly? It is dangerous to claim to know the mind of God and tell him how he ought to act (just ask Job!). But we have a clear record of how God did act through natural history. What we see there is consistent with Jesus’s description in the Parable of the Sower, where the Sower lavishly distributes seeds. Some seed never took root at all, some sprang up quickly but didn’t last long because it fell on rocky ground, and other seed was out-competed by thorns. But some found fertile soil and produced the plants the farmer intended (see N.T. Wright’s commentary connecting creation to the Parable of the Sower). This is the same pattern we find in the natural history of life on Earth. If we question why the Creator allowed millions of species to die out, we might as well question why the Sower wasted so much seed. Perhaps efficiency wasn’t the primary goal. We can praise God for partnering with the created order to bring about the remarkable lavishness of life.
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Charles Foster | Inhabit the World