The Case for a Creator - Lee Strobel [26]
“The point I want to make is this: quite unintentionally, Berra had illustrated the fact that merely having a succession of similar forms does not provide its own explanation. A mechanism is needed. With the Corvette, that mechanism is human manufacturing.”
“What mechanism is proposed for Darwinism?” I asked.
“One is called ‘common developmental pathways,’ which means if you have two different animals with homologous features and you trace them back to the embryo, they would come from similar cells and processes. This happens to be mostly untrue.
“I mentioned frogs earlier. There are some frogs that develop like frogs and other frogs that develop like birds, but they all look pretty much the same when they come out the other end. They’re frogs. So the developmental pathway explanation is false—I don’t know anybody who studies development and takes it seriously.
“A more common explanation nowadays is that the homologies come from similar genes. In other words, the reason two features are homologous in two different animals would be that they’re programmed by similar genes in the embryo. But it turns out this doesn’t work very well, either. We know some cases where you have similar features that come from different genes, but we have lots and lots of cases where we have similar genes that give rise to very different features.
“I’ll give you an example: eyes. There’s a gene that’s similar in mice, octopuses, and fruit flies. If you look at a mouse eye and an octopus eye, there’s a superficial similarity, which is odd because nobody thinks their common ancestor had an eye like that. What’s more striking is if you look at a fruit fly’s eye—a compound eye with multiple facets—it’s totally different. Yet all three of these eyes depend on the same or very similar gene.
“In fact, it’s so similar that you can put the mouse gene into a fruit fly that’s missing that gene and you can get the fruit fly to develop its eyes as it normally would. The genes are that similar. So neither the developmental pathway explanation nor the similar gene explanation really accounts for homology.”
I asked, “What’s the answer, then?”
Wells shrugged. “Frankly, it remains a mystery. If you read the literature on homology, the experts know it’s a mystery. They may not give up Darwinism, but they know they haven’t solved the problem. To me, if you haven’t solved the problem of a mechanism, then you haven’t distinguished between common descent and common design. It could be either one. The evidence isn’t pointing one way or the other.
“I think students deserve to know that scientists haven’t resolved this problem. Instead, some textbooks simply define homology as similarity due to common ancestry. So the theory becomes true by definition. What the textbook is saying is that similarity due to common ancestry is due to common ancestry. And that’s circular reasoning.”
HUMAN GENES, APE GENES
Since Wells had brought up genetics, I was reminded of another question I wanted to raise with him about the theory of common descent. “What about recent genetic studies that show humans and apes share ninety-eight or ninety-nine percent of their genes?” I asked. “Isn’t that evidence that we share a common ancestor?”
“If you assume, as neo-Darwinism does, that we are products of our genes, then you’re saying that the dramatic differences between us and chimpanzees are due to two percent of our genes,” he replied. “The problem is that the so-called body-building genes are in the ninety-eight percent. The two percent of genes that are different are really rather trivial genes that have little to do with anatomy. So the supposed similarity of human and chimpanzee DNA is a problem for neo-Darwinism right there.
“Second, it’s not surprising that when you look at two organisms that are similar anatomically, you often find they’re similar genetically. Not always; there’s a striking discordance with some organisms. But does this prove common ancestry?”
He shook his head as he answered his own question: “No, it’s just as compatible with common design as it is with common