Previous posts
Personal Preface
Forward and Introduction
Evolution as a Scientific Theory
1. 1. In chapter 2, Dennis Venema gives a basic explanation of how genes replicate themselves and activate proteins. It is actually a quite impressive simplification of genetic science. In the process, he gives us a small taste of the genomic evidence for evolution. At the end of the chapter, he says, “It is no exaggeration to say that (the very, very few) trained biologists who reject common ancestry do so because of prior religious commitments, not for scientific reasons” (40).
He actually quotes from a blog post of one of the them. Todd Wood is a young earth creationist by faith. He is quite clear, however, about how the evidence looks. “Evolution is not a theory in crisis… There is no conspiracy to hide the truth about the failure of evolution… I say these things not because… I’ve ‘converted’ to evolution… Creation students, listen to me very carefully… evolution is an extremely successful scientific theory. That doesn’t make it ultimately true… It is my own faith choice to reject evolution” (41).
I am just a beginner when it comes to such things, but my guess is that the situation is this. We could suppose, by faith, that God created in an instant the genomic map of all organisms to look as if they could have gradually evolved following processes we now can observe on a small scale. But the most natural explanation, if we had no prior commitments to go either way, would be to conclude that there has been a gradual development from simpler to more complex organisms over millions of years.
2. Some of the chapter consists of some basic genetics. Most of us have heard of DNA. DNA exists in a double spiral. Sections of DNA are called “genes,” and sections of genes are called “chromosomes.” Humans have 46 chromosomes, 23 from our father and 23 from our mother. Women have two “X” chromosomes. Men have an X and a Y chromosome. In children, women always contribute an X chromosome, while men contribute either an X (making it a girl) or a Y (making it a boy). So Henry VIII should have had himself executed for not having a boy.
There are only four basic building blocks in DNA, chemicals called cytosine, guanine, adenine, and thymine. Cytosine only bonds with guanine, and adenine only bond with thymine. So you can replicate a strand by breaking it in half and then making all these “nucleotides” available. The right ones will find the right plug-ins and bond. In fact, this is how our cells reproduce.
It is also how our DNA puts into motion our physical characteristics. Something called “messenger RNA” duplicates one of the DNA strands, takes that information off and uses it to produce a variety of proteins, which in turn activate things like our eye color or hair color or nose length, etc.
There is apparently a lot of dead space in our genes, stuff that doesn’t do much of anything. In fact, only about 5 to 6 percent of our genome are the actual genes. Three genes make a codon, which collectively code for the production of a particular protein.
3. Errors and mutations do happen. Perhaps a nucleotide doesn’t bond to the right corresponding nucleotide. Perhaps a “stop” mutation cuts off the gene so that it doesn’t finish giving complete information. Perhaps there is a deletion mutation, which throws off the three codon pattern.
For a parent-child generation, of the some 3 billion pairs of nucleotides in our DNA, there might be about 100 mutations, most if not all of which will go completely unnoticed.
4. None of the above is particularly controversial. What is controversial is how to interpret what we observe when we set the genome of humans alongside chimpanzees, gorillas, orangutans, even chicken, dogs, and whales. Venema gives the example of insulin in dogs and humans. The gene sequence has a great deal in common.
In fact, it has enough in common that dog insulin would work in a human. Apparently, there is a lot of wasted space in DNA so that there can be quite a bit of variety and it all still work. This is not how a German would design it—too much unneeded and irrelevant space. But you can imagine that if a process was wandering somewhat randomly, it would be convenient if you only had to randomly come close for something to work.
Then he puts the sequence of chimpanzees, gorillas, and orangutans alongside as well. Even closer agreement to the human sequence. Chimpanzees and gorillas are slightly closer to humans in sequence than orangutans.
Later in the chapter, he looks that the olfactory sequence for primates. It turns out that there are the remnants of genes that do not function that are present in, say, wolves. Humans, chimpanzees, gorillas, and orangutans all have a certain stopped gene that is complete in wolves. This is a shortened gene that doesn’t do anything. Humans, chimpanzees, and gorillas all have a certain gene deleted that wolves have and orangutans still have. Humans and chimpanzees have a deletion that the gorillas and orangutans still have. Meanwhile, each of these primates have a mutation in this sequence that none of the others have.
So this could all be God having fun, knowing that in the early 2000s humans would be able to unlock these codes. Wait for it, Gabriel, Francis Collins is almost ready for that joke we planned 6000 years ago. But if we were just going on the evidence alone, we might hypothesize that orangutan split off from a common ancestor first, then gorillas, then lastly chimpanzees and humans. This explains why some still have functioning genes that wolves and others still have working and why others have the same traces of earlier mutations.
Similarly, the stretch of human genes that corresponds to the part of the chicken gene that codes for an egg shell has a large number of nucleotides in the same sequence. It’s just that the key genes to make a shell are missing in humans. But there is a lot of junk in that stretch of human DNA that corresponds to a stretch of chicken DNA that works.
5. I found his opening to the chapter brilliant, since I love languages. First, he compared genomes to languages. He has a background in West Frisian in the Netherlands and put two sentences up next to each other, Apparently they sound much the same:
English: “Butter, bread, and green cheese is good English and good Frise.
West Frisian: “Bûter, brea, en griene tsiis is goed Ingelsk en goed Frysk.
By implication, the young earth creationist would have to say that God created these two languages to look and sound very similar, but he created them this way from the very beginning. He created them to be very, very similar but there would be no historical relationship between them.
If we had no prior assumptions, however, we would more naturally conclude that at some point, perhaps in the 600s AD, a common group of Anglo-Saxons split, some going to the island of England and others staying nearby on the continent. Over time, little variations arose in the way they wrote and pronounced certain words. Today, you can see a common ancestry, but the isolation of the two has resulted in some interesting “mutations.”
He shows the same in English translations of John 14:6 from the 1300s to today. Wycliffe spelled truth, “treuthe.” Tyndale in the 1500s spelled it “truthe.” The original 1611 KJV said “trueth.” And the 1769 edition of the KJV says “truth.” Same word, variations over time.
