How the Evolution Story Became Like Jellyfish
“How the [blank] got its [blank]” is the template for story titles imitating Rudyard Kipling’s Just-So Stories: i.e., How the Camel Got His Hump and How the Leopard Got His Spots. Kipling wrote these as silly stories to entertain children, not to be taken seriously by scientists. Knowing that creationists often criticize Darwinian explanations as Just-So Stories, was Amber Dance being sarcastic or whimsical when she titled her article on Nature News “How the jellyfish got its sting”? Apparently the latter (or neither) because she dove into the genre forthwith: “From a bacterium, surprisingly.”
The article discussed apparent evidence for widespread lateral gene transfer among multicellular animals. In particular, a French team supposed jellyfish got the toxin in their stinging cells from bacterial genes. Comparing genomes, they deduced that the same gene jumped between cnidarians (jellyfish, corals, and anemones), sponges, worms and fungi. The team lead said, “horizontal gene transfer is often neglected, and could sometimes be more important than we thought.”
If true, this scrambles attempts to understand common descent. It’s understandable that other evolutionists didn’t want to take that plunge.
“There are other explanations for the incongruencies they see in the tree,” agrees Casey Dunn, an evolutionary biologist who studies phylogenetic problems at Brown University in Providence, Rhode Island.
For instance, the gene could be vertically transferred from a distant progenitor, before being lost from some organisms. Or, it may be possible that more than one animal independently evolved the gene; such sequence conversion is not unheard of, Dunn says. “At the end of the day, it will probably take far more data to paint a conclusive picture of what’s happening.”
Rabet responds that since the PGA synthase gene is approximately 1000 bases long, it is statistically unlikely to be the product of multiple distinct genes converging on the same sequence.
And if the gene was lost from all but the cnidarians and a few other animals, it must have disappeared from all related organisms. “It’s possible, but we need to imagine a lot of lost genes,” he says.
The Stuff Happens Law thus becomes the null hypothesis, unless one wants to fill the explanation with imagination of statistical unlikelihoods.1 Another alternative is to give up on evolution and explore alternatives. Any chance of that happening?
Using phylogenetic analysis, Rabet and his colleagues found that the cnidarian gene fits well into the bacterial family tree. They also showed that the gene turns on in at least one jellyfish, Clytia hemisphaerica. The same gene pops up in certain sponges, worms and fungi, suggesting it jumped between species more than once, the scientists say. It is not yet clear how the transfer might have occurred, or why this particular gene would be so well-travelled….
Scientists are finding that horizontal gene transfer, once thought to be the domain of single-celled critters, is not uncommon in the animal world, says Syvanen. “Horizontal gene transfer with the animals is going to turn out to be more widespread than anybody believes now. When that realization comes down, it will definitely change the way people think about evolution.”
The answer seems as slippery as the jellyfish they were studying. But the stinger-gene of evolution shows up everywhere, even when it has to hop around who knows how.
1. See online book for a calculation that the probability of getting one gene is one in 10236.
With the new Stupid Evolution Quote of the Week cartoon, we welcome Brett Miller to our website talent pool. His drawing of Emperor Charlie’s New Clothes removes all need for comment (click image for larger version). Watch for his occasional eye-catching graphics in days to come. Thanks, Brett! Your cartoon made our day.
See more of Brett’s work at EvidentCreation.com.