Functioning 'mechanical gears' seen in nature for the first time (2013) | Hacker News Reader

Functioning 'mechanical gears' seen in nature for the first time (2013)

phys.org

31 pointszachrose10 comments

You wonder how this near ideal shape could evolve.

Maybe a pair of opposing plates preceded this to better sync the legs, and the plates became wheels to allow longer hops. Then adding bumps to each wheel is imaginable since it would sync a bit better.

But a long series of identical deep evenly spaced detents along one wheel and a perfectly matched series of gear nubs on the opposing wheel is quite a bit more complex and a phylogeny that's not at all intuitive, to me anyway.

Evolution can be nigh-impossible to understand sometimes, but this one seems straightforward- as you mentioned, it was originally two discs, which gained bumps- bugs that had better bumps were more likely to survive, and thus the bumps probably became more defined and streamlined, forming ridges, and later "gears"- and if there's one thing the body likes to do, it's symmetry.

at the end of your last sentence, I'd generalize that to "if there's one thing the universe likes, it's symmetry."

Well, a long series of repeating patterns happen very often in organisms and have some well understood evolutionary paths.

It was even Turing that discovered how some of those patterns form.

repeating patterns are common due to segmentation and gene duplication. I suspect, and I think a lot of others do as well, that the appearance of complicated new shapes occurs fairly commonly after mutation, as a consequence of the hierarchical structure of developmental gene regulatory networks and the process of cellular differentiation. In a sense, it could be there is a collection of "modules", and successful mutations involve mostly manipulation of the regulatory network of those modules, while the modules themselves don't change very often at all (at least in part because they have so many dependent processes). By combining expression of those modules with spatial patterning.

> the legs always move within 30 'microseconds' of each other

> This is critical for the powerful jumps that are this insect's primary mode of transport

> even miniscule discrepancies in synchronisation between the velocities of its legs at the point of propulsion would result in "yaw rotation" - causing the Issus to spin hopelessly out of control.

> "This precise synchronisation would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinarily tight coordination required,"

> Interestingly, the mechanistic gears are only found in the insect's juvenile – or 'nymph' – stages, and are lost in the final transition to adulthood

So, how do the adults or other grasshoppers synchronize their jumps if the nervous system can't do it and cog-wheels aren't involved?

From September 12, 2013

Also discussed at https://news.ycombinator.com/item?id=8212984.

One must, absolutely must, wonder how many marvels of life we have destroyed having never witnessed their splendor.

But what about ATP synthase?

Reply on news.ycombinator.com