Here are some news items that have crossed the editor’s desk, discussed in brief.
Cephalopods and the Cambrian Explosion
The octopus is one of the most complex invertebrates known. If fossils from Newfoundland (pictured above) have been interpreted correctly by paleontologists at Heidelberg University, they give more worries to Darwinists: “The 522 million-year-old fossils could turn out to be the first known form of these highly evolved invertebrate organisms, whose living descendants today include species such as the cuttlefish, octopus and nautilus. In that case, the find would indicate that the cephalopods evolved about 30 million years earlier than has been assumed.” Anne Hildenbrand and Gregor Austermann from the University’s Institute of Earth Scientists say this would mean that “cephalopods emerged at the very beginning of the evolution of multicellular organisms during the Cambrian explosion.” Their paper on “A potential cephalopod from the early Cambrian” was published in Communications Biology.
Technology vs. Ecology
Wind farms are killing bats. Design advocates appreciate bats for their powered flight, echolocation and other exquisite capabilities. The crisis pits climatologists against conservationists. Researchers at the University of Leibniz are looking into improving mitigation measures, such as improving monitors on the blades or housings that can sense the echolocation clicks of bats. The windmills could then stop operation during periods of high bat activity. Alas, none of the current techniques are adequate. Different species emit clicks at different frequencies, and the clicks, which are directional with the bats’ motions, attenuate with distance. As the blades of windmills increase in length, it also becomes more difficult to monitor the bats and stop operation. “This approach is a good starting point,” a bat expert at Leibniz said after a team analyzed alternatives. “Its methodological implementation is, however, often insufficient, especially for large wind turbines.” Windmills also pose threats to birds, including several species of endangered raptors. Trick question: Which is designed, the windmill or the bat?
Those who watched Unlocking the Mystery of Life probably remember the amazing fact that the bacterial flagellum can rotate at 100,000 rpm in one direction and then switch directions in a quarter turn. Scientists in Rehovot, Israel, are homing in on the switching mechanism, finding that it “combines tight regulation with inherent flexibility.” In a paper in the EMBO Journal, they find that reversing direction is not accomplished by a simple on/off switch. Rather, the signaling protein CheY has three docking ports on two different rings. If it docks at the first port, the flagellum switches briefly from counterclockwise (CCW) to clockwise (CW) briefly, then reverts. This gives stability to the bacterium’s direction of motion. When CheY binds to the second site, tumbling occurs, which starts the cell moving in a different direction. Binding to the third site stabilizes the switched states. “Thereby, this mechanism exemplifies a unique combination of tight motor regulation with inherent switching flexibility.”
AI Debating Machine
Echoes of Alan Turing’s thought experiment about artificial intelligence (AI) good enough to fool humans come to mind in a News and Views piece in Nature. Chris Reed reports on “A fully autonomous computer system has been developed that can take part in live debates with people.” Called Project Debater, this collaborative effort by N. Slonim et al. has tackled the challenge of programming a computer that can appear to adduce evidence to support conclusions and state them in debate with a live human. AI is good at storing and retrieving facts, but argument structure was thought to be “too varied, too complex, too nuanced and often too veiled to be recognized as easily as, say, sentence structure.” It’s an “extraordinarily ambitious” project, but the question must be asked, does the machine comprehend what it is saying?
Researchers at the University of Colorado, Boulder, believe they have witnessed a form of speciation that does not involve random mutations. The Iberá Seedeater, a small songbird that lives in South America, “followed a very rare evolutionary path to come into existence at a much faster pace than the grand majority of species.” The species is closely related to the Tawny-Bellied Seedeater. Instead of evolving by random mutation or natural selection, “genetic shuffling of existing variations, rather than new random mutations, brought this species into existence — and their own behaviors are keeping them apart.” The two species, which differ only in genes involved in plumage color, could hybridize but apparently do not. Is this an “evolutionary shortcut” to speciation? Their findings are in Science.
Almost all living things use left-handed amino acids (L-aa) instead of right-handed (D-aa), but there are exceptions. “Unlike other organisms, bacteria chiral-convert L-aa to D-configurations as essential components of their cell walls and as signaling molecules in their ecosystems,” explain Masataka Suzuki et al. in Science Advances. The team found that the mammal immune system recognizes these backward amino acids and triggers formation of B cells, macrophages, and immunoglobulin to stand guard against the bacteria with D-aa in their cell walls. Symbiotic bacteria, however, need to remain in the gut, so the mammal immune system keeps them in check instead of killing them all. “Thus, chiral conversion of amino acids is linked to bacterial recognition by mammals to control symbiosis with bacteria.”
Here’s a quote from Phys.org by Erin Brandt, a Canadian invertebrate zoologist, speaking about Habronattus conjunctus — a small jumping spider with a body length of approximately 4.5 mm:
“Humans can replicate various aspects of animal in large scale, but there is no way we could make something that is four millimeters long and can move like this,” said Brandt. “We just don’t have the technology to do it. And these spiders are doing it with brains the size of a poppy seed. They’re amazing.”
Chinese and American researchers have built a biomimetic synapse. The advantage of synapses in neurons include flexibility to change the signals across the gap. This is called plasticity, and it’s a property that makes the human brain so infinitely flexible and able to store memories. Inspired by the plasticity in brain neurons, the team built an artificial synapse made of an optoelectric transistor and a triboelectric generator, described in Science Advances. “By controlling the charge transfer/exchange in the heterostructure with triboelectric potential, the optoelectronic synaptic behaviors can be readily modulated,” they say. They believe it will lead to interactive AI, perhaps like the debate computer mentioned earlier.
Listen to the Cell Symphony
Scientists at the Whitehead Institute talk about the cell symphony. A transcript of their 21-minute podcast follows the sound file. David Sabatini discusses mTOR, a protein he discovered, that turns out to have multiple immunosuppressive and anticancer effects. This protein complex is being studied heavily in multiple institutions and cancer centers. Mary Gehring discusses epigenetics and imprinting, the effect of epigenetic modifications depending on whether they are expressed by the mother or the father. Iain Cheeseman discusses the kinetochore: “I really like protein machineries, and I really like how they’re precisely controlled,” he remarks “The kinetochore is I think by far the best example.”
Only one speaker mention evolution: “But, clearly in our evolutionary history,” he says in passing. Overall, the podcast is instructive about the cell’s “orchestra” players and how they interact. The analogy of a symphony with a conductor better fits intelligent design. “Whitehead Institute scientists are showing that the cell’s many parts aren’t just a crowd going every which way,” host Conor Gearin concludes. “There are crucial organizers in the cell that help conduct the noise and turn it into a melody.”