By looking at distantly related bacteria from different branches of the evolutionary tree, the team speculate that the ability to alter torque in this way may have evolved up to two billion years ago.
“Entire branches of the bacterial family tree have evolved motors with different torques, leading to a diversity of species each geared to their own environment,” said Dr Beeby. The team is now investigating how and when the evolutionary steps that altered motor torque happened. More.
Evolved two billion years ago? That’s not a lot of time for Darwinian evolution, even if a wheel could be achieved that way, given enough monkeys, enough typewriters.
See also: You’ll never guess why biological wheels are not irreducibly complex The New Scientist writer seems anxious to so mangle the idea of irreducible complexity that “irreducible complexity” means lack of diversity and “evolved only once.”
Irreducible complexity (if you actually wanted to know)
Here’s the Significance:
Many bacteria swim using helical propellers, flagella. Intriguingly, different bacteria show different swimming abilities, strikingly illustrated by the abilities of some to bore through viscous fluids (e.g., gastrointestinal mucus) in which others are completely immobilized. We used 3D electron microscopy to show that differences can be explained by the structures of the torque-generating motors: two diverse high-torque motors position additional torque-generating complexes at wider radii from the axial driveshaft than in the model enteric bacteria; this positioning is consistent with the exertion of greater leverage to rotate the flagellum and thus greater torque generation. Intriguingly, these torque-generating complexes are scaffolded at wider radii by a conserved but divergent family of structures, suggesting an ancient origin of reconfiguring torque output. (open access .pdf) – Morgan Beeby, Deborah A. Ribardo, Caitlin A. Brennan, Edward G. Ruby, Grant J. Jensen, David R. Hendrixson. Diverse high-torque bacterial flagellar motors assemble wider stator rings using a conserved protein scaffold. Proceedings of the National Academy of Sciences, 2016; 201518952 DOI: 10.1073/pnas.1518952113