One of the problems that science textbook authors face is the fact that science is constantly changing. As we learn more about the Creator’s handiwork, we find that the science we have taught as fact is actually incorrect. Sometimes, this is because the experiments upon which those facts are based were in error. Sometimes, it’s because our interpretations of those experiments were in error. Sometimes, it’s a result of making conclusions that go beyond what the experiments actually tell us. The practical upshot of all this is that some of the things you are reading in your science textbooks are wrong.
I recently found out that something I (and most other authors) have taught about DNA is probably wrong. Most people know that DNA is a double helix. As shown in the illustration above, those two helixes wind around each other, with the information-bearing units (called nucleotide bases) inside. In order for cells to use the information in DNA, those helixes have to be separated so that the sequence of the nucleotide bases can be read. That means the helixes need to be held together when DNA is not being used, and then they must be separated when it is time for the cell to read the DNA.
How does that happen? Well, according to most textbooks (including mine), it is because the nucleotide bases form hydrogen bonds with one another. Hydrogen bonds are weaker than true chemical bonds, but they can hold things together. As I say it in my textbook, Exploring Creation with Biology, 2nd Edition:
…the attraction between the atoms in hydrogen bonding is about 15% as strong as the attraction between two atoms that have a true chemical bond linking them. Thus, the hydrogen bonds in DNA are strong enough to keep the two chains together in a double helix, but they are significantly weaker than a true chemical bond. Since they are weaker than a true chemical bond, it is rather easy for the two helixes in DNA to unravel.
This sounds great, but a recent study indicates that it’s probably not true. If nothing else, it doesn’t tell the entire story.
Symbiosis is the most relevant and enduring biological theme in the history of our planet.
If you aren’t familiar with the term, “symbiosis” refers to organisms of different species living together. There are three general forms:
(1) Parasitic symbiosis, in which one organism benefits and the other is harmed
(2) Commensal symbiosis, in which one organism might benefit but neither is harmed
(3) Mutualistic symbiosis, in which all organisms in the relationship benefit
I have written extensively on mutualistic symbiosis (see here, here, here, here, here, here, here, here, here, and here, for example). Not only does it fascinate me, but it was also the major scientific issue that led me away from atheism. When one sees the amazing mutualistic relationships that exist all over nature, it becomes clear that these organisms were designed to work together.
Back in April, I spoke at the Ohio Homeschool Convention. It is part of the Great Homeschool Conventions, at which I have been fortunate to be a regular speaker. This year, the convention graciously allowed me to do my favorite kind of presentation: A Question/Answer Session. I have done them at other conventions (see here, here, and here), and I always enjoy them, usually because I learn something. I open these sessions by simply asking for questions, and I tell the audience that the questions can be about anything. If I can’t answer a question, I am happy say the three words any scientist should be totally comfortable saying, “I don’t know.” I also tell them that if I have to say those words, I will try to find the answer later and post it on my blog.
That’s what happened at the Ohio Homeschool convention. One of the audience members asked me what a narwhal (Monodon monoceros) does with its horn. I had to tell him that I don’t know. I did tell him that it isn’t really a horn. In fact, it is an elongated tooth. I speculated about a couple of possibilities, but I couldn’t say anything for sure. That was a few weeks ago, and I have been pretty busy since then. However, I have wrapped up both the Thermodynamics course I was teaching at Anderson University, and the online classes I have been teaching this year, so I finally got around to investigating narwhals.
The short answer is that we still don’t know what a narwhal does with its tusk. The long answer, however, is much more interesting.
In 1796, Simon Pierre LaPlace predicted that there are objects in the universe which are so massive that light cannot escape them. As a result, they would be “invisible” to us. These objects have become known as black holes. More than 100 years later, Einstein published one of the most successful theories of modern science: General Relativity. A year later, Karl Schwartzchild used Einstein’s equation to define a black hole and calculate its radius, which is now known as the Schwarzschild radius. While black holes captured the imagination of many scientists, Einstein himself did not like them. In fact, in 1939, he published a paper that attempted to show they cannot exist.
Over the years, however, several lines of indirect evidence have supported the existence of black holes. For example, astronomers can measure the speed of objects in orbit around other objects. The speed of the orbiting object indicates the mass of the object being orbited. In the center of a nearby galaxy charmingly named “M87,” there is a disc of hot gas that is orbiting so quickly that the mass of what is being orbited must be three billion times the mass of our sun. However, the size of the object is, at most, the size of our solar system. Those measurements are consistent with Schwartzchild’s description of a black hole.
The more we learn about creation, the more it surprises us. While it is true in all areas of science, it seems particularly true in genetics. When I was at university, I was taught as definitive fact that each gene in my DNA determined the makeup of one protein in my body. We now know that is false. I was also taught as definitive fact that the only way a parent can transmit a trait to its offspring is through the sequence of nucleotide bases in DNA. As a result, if a new trait appears in a population, it must be due to a change in the species’ DNA sequence. We now know that is false. For example, I was taught as definitive fact in university that cave fish are blind because of mutations to their DNA. We now know that is false, at least for one species of blind cave fish.
So we now know that there are ways to inherit traits that go beyond the DNA sequence that you inherit from both parents. For example, we know that if you train mice to fear a certain smell, the next generation can inherit that fear. It’s not that the parents train the fear into their offspring (the offspring were raised separate from their trained parent). They actually inherited the fear. How in the world can a parent pass on a fear of something to its offspring? That’s what the field of epigenetics (which literally means “on top of genetics”) wants to find out.
We know that it has something to do with how an organism regulates the activity of its genes. An organism can alter chemical aspects of the DNA that are not related to its actual sequence, and that alteration can decrease the use of a gene, increase the use of a gene, turn a gene off so that it is not used at all, or turn a gene on so that it will start being used. For example, most people are not born lactose intolerant. After all, they drink their mother’s milk or a milk-based formula. Milk digestion requires the enzyme called “lactase,” which is coded for by a gene. While everyone has that gene turned on at birth, in some people, it gets turned off later on, causing lactose intolerance. Nothing has changed in the person’s DNA sequence – the gene is still there and has not been broken. However, that gene has been turned off by epigenetic mechanisms. It is thought that this process is responsible for epigenetic inheritance. To some extent, we must be able to inherit the “off” and “on” status of our parents’ genes.
One of the things I continually stress with my students is that science doesn’t have to make sense. In fact, most of the theories in my scientific field make no sense at all. Why do I believe them? Because they make predictions which are later verified by the data. That’s the acid test of a scientific theory. If it can make predictions about something that is not known and those predictions can then be tested by experiment or observation, the theory is scientific. If observations or experiments actually confirm the predictions, then it is a reliable scientific theory. For example, young-earth creationism is a reliable scientific theory, because it makes predictions which are later confirmed by the data.
The same can be said of Einstein’s theory of general relativity. Make no mistake: It’s a very strange theory. It says that what we see as the force of gravity is not really a force at all. It is a consequence of how mass warps space and time. Now that’s just crazy. We know that we stay on the surface of the earth because the force of gravity continues to pull us to the center of the earth. An apple falls from a tree because the force of gravity pulls it to the earth. The earth stays in orbit around the sun because the force of gravity keeps it there. Sir Isaac Newton himself gave us an equation for gravity, and that equation has been tested over and over again and found to be reliable. It begins “F =”. The “F,” of course, stands for force. Why,then, would you believe something as silly as what Einstein said? Because his theory made several testable predictions, and when those predictions were tested, they were confirmed.
Back in 2014, the European Space Agency launched several satellites into orbit around the earth. Satellites are generally put in a circular orbit, so their distance from the earth never changes. However, a malfunction in the rocket used to place two of the satellites caused them to be put into an elliptical orbit. As a result, their distance from the earth regularly varied. The ESA corrected the orbits as much as they could, but they remain elliptical to this day. The difference between their closest and farthest distances from the earth is about 8,500 kilometers.
While this was a disappointing mistake, two physics research teams realized that they could use it to further test Einstein’s prediction of time being affected by how close you are to a massive object. After all, at regular intervals, these satellites moved closer to and farther from earth. Their position could be accurately measured in real time, using the International Laser Ranging Service, which shoots lasers at the satellites and measures the time it takes for the light to reflect off them and return.
The teams independently examined the time measured by the clocks aboard the satellites, and they each produced a graph similar to the one at the top of this post. Both of them showed that the time measured by the clocks aboard the satellites varied just as Einstein had predicted: As the satellites drifted away from the earth, time started passing more quickly for them. As the satellites drifted towards the earth, time passed more slowly for them. What makes their results noteworthy is that this test is more precise than any other that has ever been done. Their results tell us that the maximum error in Einstein’s prediction is about 0.003%.
Like it or not, the general theory of relativity is the best description scientists have for gravity, as these misplaced satellites have further confirmed.
I was teaching one of my online biology courses yesterday and discussed something virtually every biology student learns: classifying organisms as producers (who make their own food), consumers (who eat other organisms for food), or decomposers (who decompose dead organisms for food). I then mentioned that consumers can be further classified as herbivores (eating only plants), carnivores (eating only animals), or omnivores (eating both plants and animals). I then asked the students how they would classify an alligator. Of course, they classified alligators as carnivores. I then showed them the picture above. That alligator is eating a fruit (a pond apple) on purpose.
It has long been known that alligators and crocodiles ingest plant material, but it was originally thought to be accidental. Perhaps the alligator was biting for a fish, missed, and took in some plant material that was floating in the water. However, recent research shows that in most species, the ingestion is probably not by accident. It is a part of the dietary strategy.
After class, I was looking at the scientific literature and ran across an incredible report about a similar phenomenon in bonnethead sharks. Once again, it has been well known that these sharks ingest seagrass, but it was thought to be accidental. Furthermore, since a carnivore’s digestive system is tuned towards breaking down meat, it was thought that the sharks gained no nutrition from the accidentally-ingested grass. We now know that this is definitely not the case.
The authors of the study fed bonnethead sharks a diet that was mostly seagrass with just a bit of squid. The seagrass had been labeled with a specific isotope of carbon (carbon-13), which makes up only about 1% of naturally-occurring carbon. This allowed the them to identify the chemicals from the seagrass and figure out what happened to them after the seagrass had passed through the sharks. They found that the sharks were actually digesting the seagrass and using it for nutrition. In fact, even though their diet was 90% seagrass, the sharks gained weight! Finally, the authors found that the sharks’ digestive tracts showed the activity of enzymes which are designed to break down plant matter. They write:
We show that a coastal shark is digesting seagrass with at least moderate efficiency, which has ecological implications due to the stabilizing role of omnivory and nutrient transport within fragile seagrass ecosystems.
Of course, one “take home” message from all this is that creation is marvelously complex, and our attempts to categorize it are incomplete, at best. However, it also has implications when it comes to the issue of origins. Most young-earth creationists (including myself) think that before the Fall, all animals were herbivores. We also believe in a global Flood, where Noah and his family had to care for different kinds of animals on the ark for a bit more than a year. Some of those animals were carnivores, but they could not have been fed other animals (except perhaps some sea creatures from time to time). Creationists critics often say both situations are impossible, because some carnivores must eat meat, or they will die.
If a species of shark can gain weight on a diet of mostly plants, it is at least conceivable that prior to the Fall and for a year on the ark, the animals that gave rise to the “carnivores” we see today could have lived on a diet of only plants.
The authors made this discovery while they were investigating how certain immune responses work in the brains of mice. White blood cells, the cells of the immune system, are produced in bone marrow, a soft tissue found inside some bones. The authors developed a technique to identify white blood cells produced in a leg bone (the tibia) of a mouse and distinguish them from white blood cells produced in the skull of a mouse. They induced a stroke in the mouse to activate the immune response and studied what happened. As expected, white blood cells were sent to the brain, but unexpectedly, most of them came from the skull.
Why was that unexpected? It has always been thought that white blood cells must travel through the circulatory system to get to the brain. As a result, it was assumed that any white blood cells found in the brain should come equally from all parts of the body. The fact that most of the white blood cells came from the skull indicated that there must be some “shortcut” between the brain and the skull, so the researchers used microscopes to look at the inside of the skull and the surface layers of the brain. What they found is shown in the image above.
The darkest splotches in the image are bone from the skull. The skull’s bone marrow is labelled in the figure, as is the top layer of brain tissue (labelled “Brain membrane”). Notice that there are “Channels” which connect the skull’s bone marrow directly to the brain membrane. That’s the shortcut the white blood cells took. They traveled directly from the skull’s bone marrow to the brain, making the immune response more rapid than if the white blood cells had to travel through the circulatory system.
Even though the discovery of these “brain channels” was made in mice, the authors examined skull tissue removed from patients who had been through a neurosurgical procedure. They found similar channels that were roughly five times as large as the ones they saw in the mice. Of course, they couldn’t do similar experiments on people, so they don’t know for certain that the channels serve the same purpose in humans as they do in mice. However, it makes sense that they should.
The human body is so fearfully and wonderfully made (Psalm 139:14), I am sure this isn’t the last new feature to be discovered!
It’s the beginning of another another academic year. In addition to teaching online courses, I am once again teaching Thermodynamics at Anderson University. I love teaching thermodynamics, because it is a difficult subject, but it explains so much about creation. Unfortunately, many scientists and even some engineers (like Bill Nye) don’t understand it. I hope that my students walk away with a solid grasp of the subject.
Of course, teaching at the university on top of my online courses will make me a lot busier than I should be, so I am not sure how much time I will have for blogging. I will try to write at least once a week, but we will see how that goes. For now, I hope that you enjoy this video, which is the demonstration I did for the first day of class. A variation of the first part of the demo (the aluminum foil heat engine) is in the last book of my elementary science series, Science in the Industrial Age. Students make the engine when they learn about Sadi Carnot, the father of thermodynamics.
Have you met STEVE? It’s a strange event that has been photographed by several people who spend a lot of time photographing auroras. One of them (Chris Ratzlaff) suggested the name “Steve,” which was inspired by the animated movie Over the Hedge. Apparently, one of the characters in the movie named something he didn’t understand “Steve.” When the scientific community began studying this phenomenon, they kept the name but made it more “scientific.” They called it STEVE for “Strong Thermal Emission Velocity Enhancement.”
Since STEVE events happen where auroras are found, it is reasonable to think that they are related to auroras in some way. However, auroras are visible every night when you are at high latitudes and the viewing conditions are favorable. By contrast, STEVE events are visible only a few days each year, at least according to the photographers who have documented them. Also, auroras produce a glow that spreads wide throughout the night sky, while STEVE events produce ribbons of light.
So what causes these events? Currently, scientists can’t say. The initial study said they might be similar to auroras, which are caused by high-energy charged particles that have been trapped by earth’s magnetic field interacting with molecules in the upper atmosphere. This interaction gives the molecules excess energy, and they emit that energy in the form of visible light, mostly reds, greens, and blues. Scientists looked at satellite imagery that was taken during a documented STEVE event, and they did see charged particles moving at high speeds through the appropriate region of the atmosphere, but they couldn’t say for sure that they were related to the event.