Darwin Missed the Beetle Can Opener Trick
You know those big horns on rhinoceros beetles? They’re not just for showing off. Scientists at Indiana University found a “surprising function” for them. It turns out “horned beetles use their young horns as a sort of can opener, helping them bust out of thick larval shells.”
The function of horned beetles’ wild protrusions has been a matter of some consternation for biologists. Digging seemed plausible; combat and mate selection, more likely. Even Charles Darwin once weighed in on the matter, suggesting — one imagines with some frustration — the horns were merely ornamental.
Since only the adult males retain them, biologists were misled into looking into an explanation invoking sexual selection. Armin Moczek warned biologists not to ignore the developmental stages:
Despite the growing presence of developmental biology in evolutionary studies, “Even today, evolutionary theory is very much a theory of adults,” Moczek said. “But evolution doesn’t morph one adult shape into another. Instead there’s an entire lifetime of development that we can’t afford to ignore.”
The female beetles also have horns in the embryo, he explained, but lose them after hatching. Special enzymes reabsorb the horn tissue after its function as a can opener is done. The male, meanwhile, retains it for sexual prowess, or maybe for some beetle version of Monday night football (can opener, get it?); to the horny males, the game’s not the same without beetle juice. In some species, however, it’s not beetle Bailey, but the female that retains the horn, while in others, both sexes lose them in adulthood.
Looking back on this oversight stretching back to the time of Darwin, Moczek thinks mistakes were made:
“I think these findings illustrate quite clearly the importance of development to evolutionary biology,” Moczek said. “By including studies of your organism’s development, at the very least you stand to gain fundamental insights into its biology. More often than not, however, you may prevent yourself from making big mistakes when drawing up evolutionary histories. In this case, I think we did both.” See the related story on EurekAlert.
Lest the proponents of evo-devo think they have scored a point, the authors did not explain where horn-making genes and protein machines came from. As far as the evidence goes, the ability to make horns and remove them was always present. How the traits got sorted out in the descendants of horn beetles are due to loss-of-information mutations and natural selection. Nothing new has been gained. “The hornlessness of some adult beetles is therefore not the result of an inability to make horns….,” the press release mentions, “but the reshaping or reabsorption of horn tissue before the beetles become adults.”
Evolutionists also cannot explain the sequence of events. Moczek said that they can’t tell if the horn was needed because the carapace got bigger, or the bigger carapace allowed the formation of horns. “We are left with the commonly asked question in evolutionary developmental biology, ‘Which came first?’” Generalizing that question shows that evolutionists know very little at all. Picture poor Charlie wondering in consternation what tall tale to tell about the big male horns and the hornless females. He only pondered the adults; he didn’t even think to watch the larvae pop their cans with their clever tool. Darwin disciples continue to make the same mistake and miss out on a lot of the fun.
This story is also a lesson about so-called vestigial organs and secondary sexual characteristics (e.g., see entry about male nipples, 11/28/2006). Something is not vestigial if it had a function in the embryo. Just because an organ like a tonsil or appendix looks shriveled up compared to its counterpart in other animals, and just because it can be removed without harm, does not mean it is a relic of some mythical evolutionary past. The right approach should be to look for a function when none is apparent. A little humility would have saved biologists from getting squirted when this new information popped out of the can.