> Nobody said that nature is optimal. Wheels are trivial, however not present in biology. Nature creates tentacles, not jet engines, nuclear energy etc.
Wheels are trivial but useless without bearings.
Bearings most certainly aren't trivial. All the things you listed further are dependent on bearings somewhere.
AFAIK both exist in biology. Bacterial flagellum is effectively a motor, and has a working wheel-like structure. IIRC, some crickets had an equivalent of a bearing somewhere in their anatomy too.
Evolution is a greedy, lazy optimizer, so it promotes things that work a-ok for a given environment.
It's also worth noting that wheels alone are not too useful for transportation, as they're only half of the picture. The other half is roads. That is, because we couldn't (and mostly still can't) figure out all-terrain mobility systems that could navigate diverse environments, we cheated and locally flattened the environment, to reduce the problem to that solvable by a humble wheel. Evolution can't cheat like this.
I actually googled before writing the comment (preposterous, I know; also, out of vouge, should've asked chatgpt) and the bacteria thing was the only thing I found, nothing macro scale, which made sense since it's easier to rebuild than to heal. Anything bigger than that would have to be healed and it's hard enough to fix mechanical bearings, can't imagine how to regrow or heal one even if it somehow grows. Maybe it's an issue with my imagination ;)
Good point about rebuilding vs. healing. We're kind of rediscovering it with economies of scale and price of labor making it much cheaper to replace things than to repair them.
I can imagine evolution creating macro-scale wheels that can be healed, and/or able to survive long enough before failing to be advantageous - after all, bones and teeth can hardly be healed if badly damaged, and yet they last long enough to stick around as core design elements.
This is why I mentioned roads. Whether or not evolution could iterate its way to macroscale wheels, it wouldn't, because they'd be useless without roads. Legs may be more complex overall, but they're an all-terrain solution that can be incrementally improved, and every improvement step grants improved survivability.
If that's the case why are we sending wheeled rovers to mars/moon and not something with legs?
In any case this discussion is going sideways, the point is that nature doesn't have monopoly on being optimal. This also applies to intelligence/learning/modeling something better than brain.
> If that's the case why are we sending wheeled rovers to mars/moon and not something with legs?
Because Mars is a simple and boring environment. Most of its surface, and especially the parts we target with rover missions, are effectively flat sheets peppered with rocks - a decent set of wheels and suspension is close to optimal for navigating such terrain.
Now, if we were to send missions to a planet that's mostly forests and rivers, like Earth used to be, then wheels wouldn't cut it - not before cutting down some of the forests first.
> the point is that nature doesn't have monopoly on being optimal. This also applies to intelligence/learning/modeling something better than brain.
Fair enough. Nature doesn't do globally optimal - but it makes things heavily optimized for their environment. That's why our planes are nowhere near as energy-efficient in flying as birds are, but birds cannot travel as far and as fast as our planes can.
Exactly, same with intelligence - it's polluted with emotions and all kind of "nonsense" - but it doesn't have to. We can create emotionless, super-intelligent machines exceeding human capability by far (and use them as hammers). No need to imitate every detail of the brain to extract intelligence.
The counter to this is you can end up with an exceptionally powerful, but unaligned AI, which presents a new series of 'known unknowns' and 'unknown unknowns' that we have to deal with.
> We don't need to match number of neural connections in human brain to exceed its intelligence.
That's also true because of wheels/road thing, in that we can "cheat" here too. More specifically, some of the neural connections in the human brain are dedicated to sensing, processing and controlling the dynamic state of human body. Purely-software AIs don't need those for intelligence.
Legged-robot technology is still very immature, even more so when the rover was designed. Wheels work well on relatively flat Martian terrain and are a lot less likely to break than robot legs.
Interestingly the latest Mars rover also includes a small helicopter, another technology which requires spinning something on a bearing and does not commonly exist in nature.
Wheels are trivial but useless without bearings.
Bearings most certainly aren't trivial. All the things you listed further are dependent on bearings somewhere.