As Science Observes, Talk of Evolution Fades
Here is something that emerges from stories that have appeared recently in journals and at science sites, including news that updates some of my previous articles. We find that the more detail that scientists observe, the less talk there is about evolution. Why would that be? Another point worthy of note: the more sophistication that is found in biological engineering, the more scientists want to imitate it.
Jumping Robot Success
One of the most fascinating animal stories I have reported was about springtails (here). These miniature gymnasts, ranging from 2 to 6 mm long, perform Olympic-grade leaps, accelerating up to 80g, rotating at a phenomenal rate of 290 revolutions per second. Harvard reported success at mimicking the springtail with small robots that can jump 1.4 m, 23 times their length, using a rapidly unfolding furcula resembling the device the springtail uses to launch.
Robert J. Wood’s lab had earlier reported mimicking the mantis shrimp’s club, a device that I described here. Both the springtail and mantis shrimp use “latch-mediated spring actuation, in which potential energy is stored in an elastic element … that can be deployed in milliseconds like a catapult.” Does he believe it evolved? Hard to say. The news release only says that the inspiring springtail is ubiquitous “both spatially and temporally across evolutionary scales.” That could be interpreted as stasis
Our Bubble-Wrap Noses
Feel your nose. New Scientist announced a new fact about that monument on our facial map: “Your ears and nose are made from tissue that looks like bubble wrap.” It’s a different form of cartilage from that found in other parts of the body. Maksim Plikus at UC Irvine found this by accident when studying mouse ears, lending support to Young’s Law of Science: “All great scientific discoveries are made by mistake.”
Our bubble wrap cartilage, which the UCI team calls lipocartilage due to its fat content, does not pop when squeezed, nor does it make good shipping material, but the UCI team believes that “harnessing it could make facial surgery, like nose reshaping, easier.” One item of ethical concern appeared in the article: “The team also found lipocartilage in human ear and nose samples collected from medically aborted fetuses.”
Magnetic Navigators
A sea turtle hatchling disappears into the waves. How does it know where to go? And how does it know the way back years or decades later? These questions were explored ten years ago in Illustra Media’s film Living Waters: Intelligent Design in the Oceans of the Earth. It suggested that the turtles follow magnetic waypoints in an inherited map. Now, scientists at the University of North Carolina at Chapel Hill have filled “an important gap in our knowledge” by confirming that the turtles can memorize magnetic signatures. “Through controlled experiments, the research team demonstrated that loggerhead turtles can indeed learn and remember the magnetic fields of areas where they receive food.” Incidentally, it was good to hear from Deakin University that the endangered turtles are making a comeback thanks to conservation efforts.
UNC’s discovery adds understanding about animal migration in general. “More broadly, these findings could apply to a wide range of migratory animals that rely on magnetic cues for navigation,” they said. Indeed, earlier news from the University of Oldenburg found that desert ants memorize their nest location when out on learning walks by paying attention to the polarity of the earth’s magnetic field. Changing the inclination of artificial magnetic fields had no effect, they found, but changing the azimuth made the ants aim in the wrong direction. All is not lost, however; a recent paper in Current Biology reports that desert ants use a “variety of navigational tools” in their learning walks, including path integration: “Once the learning walks are completed the ants can reach the nest from any direction.” For more on the remarkable abilities of animals to navigate by the earth’s magnetic field, see Eric Cassell’s excellent book Animal Algorithms published by Discovery Institute Press.
Zooming in on the Flagellar Stator
Calling the iconic bacterial flagella “amazing natural machines!”, news from the Nagoya Institute of Technology announced new details in the stator at unprecedented resolution. Using CryoEM (see my article here about super-resolution microscopy), Japanese scientists peered into sodium ion channels that are arranged in a ring around the stator. They determined that these channels contain “key molecular cavities for sodium ions” that “act as size-based filters that allow the intake of sodium ions — but not other ions — into the identified cavities.” This is remarkable given that some flagellar motors operate on protons, which are smaller.
As hydrated sodium ions flow through the cavities, an accompanying video explains, they generate conformational changes, “transferring the mechanical energy to the rotor to make the motor spin.” The team identified numerous specific amino acid residues in the channel involved in size filtering. Even so, “the mechanism of how the ion flux drives the rotation is still unknown,” their paper in PNAS says. As scientists around the world continue collecting detailed clues about this molecular outboard motor, it’s exciting to see them approach the secret of torque generation. And so far, as this evolution-free paper illustrates, the irreducible complexity has been growing ever since Michael Behe brought this iconic motor to our attention in 1996.
Machine Recycling
Some eukaryotes alternate between amoeboid and flagellated forms. Swiss scientists publishing in EMBO Reportsexamined one shape-shifter: “The early branching eukaryote Naegleria gruberi can transform transiently from an amoeboid life form lacking centrioles and flagella to a flagellate life form where these elements are present, followed by reversion to the amoeboid state.” When it comes time to recycle the eukaryotic flagellum (different in design from bacterial flagellum), the axonemes “fold onto the cell surface and fuse within milliseconds with the plasma membrane” (emphasis added). That’s radically fast recycling! Then, a molecular machine called spastin cuts up the axonemes into similarly sized chunks and sends them to the lysosome, where the molecules are disassembled for reuse.
The researchers also found that the centrioles, parts of the basal bodies of the flagella on the inside, get recycled by lysosomes or proteasomes too. Some centrioles, though, are shed to the outside of the cell. “Remarkably, we discovered that externalized centrioles can be taken up by another cell,” they noted. What they found is probably not unique. “Collectively, these findings reveal fundamental mechanisms governing the elimination of essential cellular constituents in Naegleria that may operate broadly in eukaryotic systems.” Evolution made only a cameo appearance in the paper but was not essential to the science.
Cable Bacteria Update
Finally, new research on cable bacteria (see here) was published in PNAS in January. A study from the Naval Research Laboratory “presents the direct measurement of proton transport along filamentous Desulfobulbaceae, or cable bacteria. So it’s not just electrons that can travel on these miniature wires, but protons, too. And they go long distances. (Well, that is, if you consider 100 micrometers a long distance.) Why is this significant? “The observation of protonic conductivity in cable bacteria,” they say, “presents possibilities for investigating the importance of long-distance proton transport in microbial ecosystems and to potentially build biotic or biomimetic scaffolds to interface with materials via proton-mediated gateways or channels.” Proton transfer, they believe, may play essential roles in the ecology at the micro level. And as they point out, the imitation of nature in biomimetics remains a hot pursuit. Has Darwinism helped? “However, despite these hypotheses, the evolutionary benefit of this phenomenon, its role in environmental settings, and its role in microbial interaction remain unknown.” Let engineers figure it out.
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