

Image courtesy of Wikipedia Commons



Image courtesy of Wikipedia Commons

Evolution may be viewed as a controversial subject by much of the US population, but evolutionary biologists frequently complain that this controversy is manufactured by opponents of evolution who have a very flawed understanding of what the science of evolution is. This poor grasp of the science was demonstrated once again in a talk given by Intelligent Design advocate Jonathan Wells, who claims that "DNA does not control embryo development."Wells, who has a PhD in biology, (I don't know what the director of graduate studies at UC Berkeley was smoking), has repeatedly demonstrated his cluelessness about basic elements of biology, and he is a clear illustration of why a PhD does not necessarily indicate anything about its holder's knowledge. Over at Pharyngula, PZ Myers has a thorough takedown of Wells' absurd talk. The talk is based on the bizarre claim that "DNA does not control embryo development." If that's true, Wells argues, then the whole tottering neo-Darwinian edifice collapses, or something like that.PZ, who unlike Wells actually uses his developmental biology degree to do science, slices and dices these weird creationist claims with his usual facility. One of Wells' PowerPoint slides says that a "paternal centrosome, without DNA, is sufficient to generate a complete parthenogenic frog from from a living egg." Go visit PZ if you want a definition of the terminology, but taken literally this false statement claims that you can make a frog without DNA, which is clearly not true. To be charitable, Wells appears to be referring to the fact that you can generate embryos without paternal DNA. As PZ explains, you can make an egg cell "think" that it has been fertilized, and get it to start dividing with only maternal DNA around. How that phenomenon disproves evolution is beyond my comprehension.In any case, I'm not writing to echo Myers' takedown; head on over and read the whole thing yourself. But you've got to give Wells credit for one thing: whether he wants to or not, he's making a prediction. It works like this: if you take the DNA out of an egg cell of one species (let's say, a cow oocyte), replace it with the DNA of another species, like a cat, and then prompt that egg to develop into an embryo, which animal will you get, a cow or a cat? If Wells is right, then that cow egg with cat DNA will develop into a cow. The scientific world says you'll get a cat.Well, that experiment's been done, and unfortunately for Wells, it turns out that DNA does determine which animal you get. The technique to do this is called 'interspecies somatic cell nuclear transfer,' and it is being attempted in the hope that we'll be able to clone endangered or even extinct species. For example, if you want to resurrect woolly mammoths, you take mammoth DNA, put it into an elephant egg (minus elephant DNA), and implant that egg into an elephant.In fact, the experiment has been done many times already. In one case researchers took DNA from an endangered European mouflan (species Ovis orientalis):They put the DNA into an egg (missing its own DNA) from a domesticated sheep (species Ovis aries):The result? A lamb that is a European mouflan (you can see the cloned lamb next to its biological-but-not-genetic mother):In other words, DNA does in fact control embryo development. To be honest, no sane scientist thought the outcome would be any different, because decades of genetic experiments revealed that you can change how an embryo develops by altering a single gene, while leaving everything else constant. Thanks to cloning, another strange attack on evolution bites the dust.