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First Mechanical Gear Found in a Living Creature

popularmechanics.com

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Re: First Mechanical Gear Found in a Living Creature

#141

Post by nialo »

zdean wrote: post #128
m-photonic wrote: post #88

"They're rather specialized, and there are lots of other jumpers that don't have them, so there must be some kind of advantage." Not necessarily. Evolution has a lot to do with path dependence and in no way guarantees the best of all possible adaptations.

Could you clarify/expound on this?

The simple way to see this is that evolution is essentially just the simplest possible hill climbing algorithm (at each step, change one random gene on some fraction of organisms in a random way, keep the best set of genes for the next step).

It can do amazing things, but only because it's had millions/billions of years and an entire planet to run on.

Re: First Mechanical Gear Found in a Living Creature

#142

Post by ByronT »

stcredzero wrote: post #129

> In 2 milliseconds it has bulleted skyward, accelerating at nearly 400 g's—a rate more than 20 times what a human body can withstand. This is entirely incorrect. 9g is the limit that someone can stay conscious, but the body can withstand a lot more. Experimental subject John Stapp withstood 46.2 g. http://en.wikipedia.org/w/index.php?title=G-force#Horizontal...

I think it depends on the direction of the acceleration. The John Stapp experiment was horizontal acceleration, right? Right above that:

"... if g-forces are not quickly reduced, death can occur. Resistance to "negative" or "downward" g, which drives blood to the head, is much lower. This limit is typically in the −2 to −3 g (about −20 m/s² to −30 m/s²) range."

Re: First Mechanical Gear Found in a Living Creature

#143

Post by jk4930 »

bernardom wrote: post #134
jerf wrote: post #132

Earlier quoted context omitted.

Evolution works by incremental changes, each of which to a first approximation must be at least neutral and preferably advantageous to producing offspring. In order for evolution to get from A to B, there must be a path of incremental advantageous changes to get from here to there. It can't magically leap from one optimum to another. So you see things like the way the same basic body plan is reused endlessly in the n…

Whoa. That blew my mind. So we're evolving in such a way to be able to make combinatorial multi-gene changes- by evolving brains big enough to be able to develop gene engineering?

There's another term from the mentioned "Selfish Gene" (which is a book by the same title): https://en.wikipedia.org/wiki/Memetics

It's a view on how ideas spread and use hosts (e.g., human brains) as carriers. They mutate, they're selected, they compete for "brain space". One funny perspective is that we're the slaves to genes and memes, both using us to survive. We're just carrying out their orders. :)

(In the end it's just a way to look at information diffusion with focus on the way how ideas replicate and the condition of their success or failure over time, abstracting away from social/cultural context and other hard to grasp things.)

Re: First Mechanical Gear Found in a Living Creature

#144

Post by snowwrestler »

emiljbs wrote: post #102
snowwrestler wrote: post #96

Earlier quoted context omitted.

Evolution is the ultimate proof of the power of agile engineering--ship on a schedule, test with real data, then work on the next iteration, keeping the good and discarding the bad.

Except that the new iteration is pretty much making random changes.

A common misperception but not true, because traits are heritable and the environment selects for fitness.

Mutation and genetic drift play a role in evolution, but are not the sole source of changes.

Re: First Mechanical Gear Found in a Living Creature

#145

Post by mikeash »

shabble wrote: post #137
nether wrote: post #49

Earlier quoted context omitted.

Top comment is pretty much, "this changes my whole theory of nonsense which I just invented." It's a pseudoscientific strawman and I can't believe it was upvoted. As a mechanical engineer I see tons of mechanical components in the human body. Diaphragm pumps, ball and socket joints, pinned joints, tensile supports. None of this makes you a cyborg. https://en.wikipedia.org/wiki/Not_even_wrong

> As a mechanical engineer I see tons of mechanical components in the human body. Diaphragm pumps, ball and socket joints, pinned joints, tensile supports. The chemical engineer points at the vast complexity of enzyme catalysed reactions and intricate supply chains of nutrients. The electrical engineer observes the networked structure of the nervous system, the myriad signal processing pipelines built all from simila…

Physicists think God is a physicist, since everything runs according to simple laws.

Engineers think God is an engineer, because He created order out of chaos, and that's what engineers do.

Programmers think God is a programmer, because where do you think the chaos come from in the first place?

Re: First Mechanical Gear Found in a Living Creature

#146

Post by upquark »

jerf wrote: post #132
zdean wrote: post #128

Earlier quoted context omitted.

Could you clarify/expound on this?

Evolution works by incremental changes, each of which to a first approximation must be at least neutral and preferably advantageous to producing offspring. In order for evolution to get from A to B, there must be a path of incremental advantageous changes to get from here to there. It can't magically leap from one optimum to another. So you see things like the way the same basic body plan is reused endlessly in the n…

Awesome post. About the "fantastic two-gene change": can't there ever be a force pushing for a species to obtain two independent mutations more or less simultaneously? What I mean by that is pressure on a species to maintain / promote a few existing mutations in the population (each individual may carry one, or the other, or none, but the offspring of carriers is likely to end up with more than one). I imagine in very narrow bottlenecks this could be the case, e.g. tough ecosystem forcing early humans to a. become bipedal and b. think/plan better. Such bottlenecks could also be caused by inter-species dynamics, climate change, etc.

Actually the more I think about it, the more I am convinced that multiple interacting species introduce a serious argument against the blind hill-climbing view of evolution. Essentially what you have is not a single point on a landscape blindly climbing in the direction of the gradient, but a probability distribution with a given mean point that could jump to another mean currently at its periphery given enough pressure / interference. E.g. a newly migrated predator eating away 90% of variance of the distribution of some existing sheep-like species, leaving only its tough "tail", thus severely relocating the centroid. Maybe this is something trivial I'm just realizing, I'm not a biologist.

Re: First Mechanical Gear Found in a Living Creature

#147

Post by swamp40 »

dsuth wrote: post #100
swamp40 wrote: post #77

It is for beauty like this that I believe all living things were originally designed by some intelligence, somewhere. Perhaps designed to mutate and evolve, or perhaps that was a limitation in the source materials, but there are some beautifully engineered living systems on our planet.

You're fitting the data to support your preconceived ideas. That never works out well.

Well, I can't disagree with that.

Re: First Mechanical Gear Found in a Living Creature

#149

Post by estebank »

dsuth wrote: post #99
andrew_gardener wrote: post #17

Earlier quoted context omitted.

While I can't be certain, I believe it might not handle wear very well based on the article. Near the end they mention that it molts several times growing new, larger versions of the gears. When its an adult, it actually loses these gears entirely. Their theory is that when the insect is fully grown is gets rid of the gears since it can no longer molt and thus replace them if they become damaged.

What's interesting is that their replacement - essentially friction pads, IS expected to last the remainder of their life (and for other similar insects). I would have expected gears to last longer than something relying on friction, especially at those levels of energy.

I guess that the difference is the failure mode for friction pads is more gracious than for gears, making survival more likely.

Re: First Mechanical Gear Found in a Living Creature

#150

Post by upquark »

jk4930 wrote: post #143
bernardom wrote: post #134

Earlier quoted context omitted.

Whoa. That blew my mind. So we're evolving in such a way to be able to make combinatorial multi-gene changes- by evolving brains big enough to be able to develop gene engineering?

There's another term from the mentioned "Selfish Gene" (which is a book by the same title): https://en.wikipedia.org/wiki/Memetics It's a view on how ideas spread and use hosts (e.g., human brains) as carriers. They mutate, they're selected, they compete for "brain space". One funny perspective is that we're the slaves to genes and memes, both using us to survive. We're just carrying out their orders. :) (In the end…

Wouldn't it be in the best interest of memes to never let us figure them out though? To never obtain this view of the world where memes are exposed for the parasites that they are? Maybe "theory of memetics" is a next-generation meme that took over our collective consciousness to exterminate all the other primitive memes and gain world domination :)
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