This Might Be the World's Most Underwhelming Evidence for Darwinian Evolution - Evolution News & Views

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This Might Be the World's Most Underwhelming Evidence for Darwinian Evolution


Our old friend Chris Mooney is excited that he seems to have touched a chord with a recent article for Mother Jones. What's he got this time? It's "a stunning piece of evidence in favor of the theory of evolution -- one that terrifies creationists." In the original article science journalist Mooney brandished human chromosome 2. In a new piece for the same publication he comes back at us again with it. He breathlessly announces the evidence here is "even stronger than I let on in my last article." Why did he hold back till now? I don't know. He believes this is a real Stop the Presses kind of argument.

Oh please. If there are any "creationists" out there who are running scared, they need not do so. The new article is titled "You Share 98.7 Percent of Your DNA with This Sex-Obsessed Ape," referring, of course, to the precious bonobo, a chimp-like ape famous for its progressive sexual habits. Just by itself, the genetic similarity between us and apes such as the bonobo is supposed to be of knockdown importance.

But what else would anyone expect, whether on a model of Darwinism, intelligent design, or creationism? Apes and humans are similar in many ways, and you don't need Darwinian evolution to see this.

My family visited Seattle's Woodland Park Zoo recently and spent time looking at the orangutans. I was mesmerized as I watched one large, sprawling fellow -- I think it was Heran, a 25-year-old male Sumatran-Bornean hybrid -- working a cup of yoghurt. It was eerie. Separated from him by just a pane of glass, I was struck most by his eyes, which he lifted to mine occasionally in seeming disappointment, as if to say, "I can't get the last bit at the bottom of the cup!" That is frustrating, isn't it?

People have known about the resemblance between apes and us for a long time. I just looked up the medieval Hebrew commentaries on the rare use of the term for ape, kof, in the Bible. The word appears twice, without explanation, so commentators had to explain to readers -- living, let's say, in 12th-century Provence -- what a kof is. They said that it's a creature that in form is like a man, virtually a copy of us. The word itself is easy to remember since in Hebrew the same letter represents f and p. As a friend points out, kof sounds like our English word "copy."

None of this is news. Now, let us reason together. As Ann Gauger says in the new documentary The War on Humans, the ballyhooed genetic similarity between apes and humans refers only to protein-coding DNA, as opposed to species-specific non-protein-coding DNA. The latter, formerly dismissed as "junk," is now increasingly understood to be vital to life.

All of life is protein-based, with these molecular machines serving as the building blocks of animals and plants. Imagine you were to go back in history centuries before the structure and function of DNA were known. You find a thoughtful person who is familiar with the idea of an ape, even if she's never seen one, and is aware of their similarity to human beings. She's also aware that of living things in general, some seem very distant in form from humans, while others appear less distant.

You ask her to suppose that somehow a kind of recipe for our physical being, specifying the ingredients, is inscribed in the body itself. Different kinds of animals naturally have different recipes for the physical stuff that makes up their bodies. Take a cow and an ape. Which would she expect to require a recipe closer to that for a human? Obviously, the ape!

Let's say the similarity can be measured on a percentage scale, from 1 to 100. A hundred percent ape-human similarity would be surprising. Zero percent would also be puzzling. You're going to expect a figure somewhere between 1 and 99, probably a lot closer to 99 than to 1. If you told someone who lived in medieval Provence, a religious person with no frame of reference that would include Darwinian evolution, natural selection or common descent, that the material "ingredients" for a man and ape were 98 percent similar while the ingredients for a man and a cow are only 80 percent. Would she be surprised? Would her faith be rocked? Of course not.

Sharing a high percentage of protein-coding DNA with bonobos, chimps or orangutans, higher than we share with bovines, for example, is simply what common sense would lead anyone to expect.

But Mooney isn't done yet. It's human chromosome 2 that he thinks is the clincher. Chimps, gorillas, orangutans and bonobos all have a pair of shorter chromosomes, 2a and 2b, where we and our ancient relatives, Neanderthals and Denisovans, have one longer chromosome. There is sequencing evidence, though not dispositive, that a fusion event occurred at some time in the past. It may be that our ancient ancestors had two chromosomes there, like the apes do, which subsequently joined.

This makes Mooney caper and dance. For a sober analysis of the evidence for a fused chromosome, see Casey Luskin's comments here and here. But on the point about a past fusion, let's stipulate for simplicity's sake that Mooney is right. Such an event fits well into a Darwinian story of common descent, where apes and humans share ancestry, with a hypothetical common ancestor that had 24 total chromosomes. After the human line split from other primates, the fusion occurred and we were left with only 23.

But the fact fits no less smoothly into non-Darwinian scenarios. It's only a "stunning" confirmation of Darwinism if you assume Darwinian evolution to begin with. We already know that humans and apes have highly similar genomes -- we know that by empirical science that has nothing to do with evolutionary arguments. So grant that our ancestors had 24 chromosomes, just like our "copies," the apes. That would not be shocking. For whatever reason, some time later, our line of descent experienced a fusion of chromosomes 2a and 2b, which we inherited. Humans today are thus left with only 23 chromosomes.

This suggests the common descent of human beings. It says nothing at all about shared ancestry with apes. It certainly says nothing about life developing without plan or purpose. None of this poses the least problem for an inference to ID, which claims to find evidence of design in nature, not the absence of evidence for life's having a long and fascinating history.

Mooney, in fact, seems to miss that genetic similarities could indicate common design just as much as common descent. Software designers reuse similar programming modules in different programs, so wouldn't a species designer reuse similar genetic programs in different species? Doing so seems only natural.

One might also ask, how does Mooney's argument provide us with an objective criterion for confirming common ancestry? If 98 percent genetic similarity confirms common ancestry for humans and apes, would a mere 80 percent, as between humans and cows, disconfirm it? Or how about the (perhaps) 50 percent similarity that some of our genes have with bananas? Is there any metric available for falsifying common descent? No, there isn't. In pointing to human-ape genetic similarity, Mooney isn't making a scientific argument. He's making an emotional one.

Sorry, Chris Mooney. What you've come up with could be the single most underwhelming piece of "evidence" for Darwinian evolution currently available.

I'm now on Twitter. Find me @d_klinghoffer.

Photo: Bonobos at the Cincinnati Zoo/Wikipedia.