First Mechanical Gear Found in a Living Creature
popularmechanics.com
popularmechanics.com
http://www.reddit.com/r/science/comments/1m9eke/scientists_d...
They're taking questions.
Not necessarily. Evolution has a lot to do with path dependence and in no way guarantees the best of all possible adaptations.
Evolution is both very powerful, with many people underestimating it, and profoundly stupid, with many people also overestimating it. Once humans really get cracking with the gene engineering (which has proved harder than we had initially hoped, but I'm still confident we'll get there), I'm sure we'll find a plethora of relatively simple changes we can make to natural organisms that may involve changing three or four genes simultaneously where no single change is advantageous, which is a thing that evolution essentially can't do.
[1]: Or at least, not yet... one bizarre-ish, "Selfish Gene" way of looking at human gene engineering is evolution evolving itself a way to make those multi-gene changes. Still not in a directed fashion, of course. But evolution will still apply to our own gene engineered creations, just possibly with a very different set of constraints, such as potentially severing the billion-year-old connection between fitness and direct biological reproduction... as I've said on HN before, you don't have to be a full-on "Rapture of the Nerds"-style Singulatarian to see that the future may get very weird....
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?
But observationally, humanity is currently in a place where that level of gene engineering is a decent bet, yes.
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.)
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.
However, in your first case, it sounds to me like you're talking about two changes, each of which are beneficial, or at least neutral. That wasn't what I was talking about, that happens all the time. I'm talking about changing two or three or four (or more) genes simultaneously in a way that each individual change, if applied on its own, would be detrimental, but the whole is an improvement.
In this representation of life it is directed and goal based. This is a misunderstanding of evolution that was common in a world that saw humanity as the peak of the process of evolution. For this reason Darwin perferred to think of it as a directionless bush rather than a directed tree.
1: http://en.wikipedia.org/wiki/File:Tree_of_life_by_Haeckel.jp...
What I mean is, a more adequate picture of the process is not a simple "path" analogy. It's more like you have a high dimensional optimization space and a wildly varying survival function, and the organisms are bouncing around this space in a random motion. This allows them to occasionally cross valleys and take very distinct paths to each far away maxima, specially if there are a few minor maxima along the way.
My point being organisms have a given capability to bounce around: they don't have to take a monotonically improving path, although this capability is limited because otherwise (if the mutation rate is too fast) the results are too chaotic.
They're somewhere in the middle of monotonically improving, guaranteed optimization (low mutation; gets stuck at local maxima) and completely random (high mutation; does not retain advantages well and leads to many deleterious results).
It can do amazing things, but only because it's had millions/billions of years and an entire planet to run on.
In this case it seems pretty obvious that gears can be better than friction at transmitting torque.
The ones that stay around long enough to be studied perhaps.
I think a better phrasing would be, "the summation of all adaptations in addition to environmental state (including benefits or constraints to itself and all others) has led to the survival in its present environment".
It's really about optimization gradients in a particular time/environmental/social niche. Everything can change with the purturbation of any factor--but that's evolution for you. Adative curve fitting.
If you read the rest of the article, that idea does become more compelling since the creature loses those gears at its final stage in life.
> Larger animals, whether kangaroos or NBA players, rely on their nervous system to keep their legs in sync when pushing off to jump—using a constant loop of adjustment and feedback. But for the issus, their legs outpace their nervous system. By the time the insect has sent a signal from its legs to its brain and back again, roughly 5 or 6 milliseconds, the launch has long since happened. Instead, the gears, which engage before the jump, let the issus lock its legs together—synchronizing their movements to a precision of 1/300,000 of a second.
The ATP synthase also works that way. The ADP and Pi are mechanically squeezed against each other in order to create the covalent bound.
See the last two videos of [0] for the general process. The first three focus on details.
[0] http://www.mrc-mbu.cam.ac.uk/category/slideshows/atpmovies
I have a PhD in Biophysics. If I ever said "ADP and Pi were squeezed together", I'd have been laughed out of journal club. The fine details of the reaction coordinate are still being argued about.
I'll grant you there are no canonical gears as a mechanical engineer would recognize them. I wasn't talking about the motive coupling. But a number of the physical structures (proteins) that couple the anchoring to the moving body have gear like properties. These are used to orient and clock the moving body in its cycle.
OK, I'll up it a notch since you guys are being picky. There are motor proteins which use ATP hydrolysis to do directed (non-random) motion. One of the plausible (IIRC it's passe now) mechanisms involved coupling the ATP hydrolysis free energy to a physical ratchet-like mechanism which, while didn't physically look like a gear when you looked at static crystal structures, seemed to behave like one using various subtle time-resolved mechanisms.
;-)
More seriously, I had inferred the squeezing from the videos I linked to.
If I understand properly, the mechanical constrains on the ADP, Pi and AA residuals involved result in the formation of the high energy covalent bound between the two phosphates.
Thus mechanical -> chemical energy.
I thought that the pressure between the electron clouds of the two molecules caused some superficial electrons to hop, resulting in the new covalent bound (that's what I meant by squeezing), and the dehydration.
Is this mostly correct (with possible intermediate steps where either the Pi or the ADP end up in a temporary covalent bound of even higher energy with subunits of the ÀTP synthase), or is this pure hogwash?
Also, thanks for the explanations regarding the flagellum, that's very interesting :-)
> I'll grant you there are no canonical gears as a mechanical engineer would recognize them. I wasn't talking about the motive coupling. But a number of the physical structures (proteins) that couple the anchoring to the moving body have gear like properties. These are used to orient and clock the moving body in its cycle.
Is it mediated by alternating, matching stripes of charged or polar AA residuals?
I knew that chemical bounds were vibrating (with a frequency proportional to their energy, E=h(nu)), but, for some reason, I had never envisioned macromolecules wiggling and vibrating as a whole.
Updating mental model :-)
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...
"... 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."
I felt bad for the monkey. But yes, direction matters.
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.
>Their idea: If one of the gear teeth were to slip and break in an adult, its jumping ability would be hindered forever. With no more molts, it would have no chance to grow more gears.
Gotta catch em all.
Repeat this with young and adult versions and see if/how much the gear system (adults don't have it) improves the odds of surviving attacks.
Either way the hypothesis they gave as to why the gears are eventually mutated away makes sense but has me wondering why they don't keep replacing them instead of settling on living without them.
Thus I'd like to quantify the edge said gears provide as a starting point for the investigation :)
The button is there to temporarily (or not) enable a tracker, when it's necessary for function - apparently, Ghostery decided the text is behind a tracker. It's strange though, I'm using Ghostery too (latest version), nothing enabled, and I didn't get the play button.
> Most other bugs synchronize the quick jolt of their leaping legs through friction, using bumpy or grippy surfaces to press the top of their legs together
Okay if you own a patent and sued someone for it, it's time to hand back the money!
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.
Like a Saturn V rocket, or an AC induction motor.
Things that make you proud to be an engineer.
Maybe whatever created these gears was being tortured by an evil master until it made something satisfactory.
I really can't say for sure...
Mind you, I'm an atheist, so this is just my understanding of the argument.
Looks like this for is as in "because", he is telling you why he belives, because of "beauty like this". You can only say you do not believe this evidence implicates that.
What I was looking for but didn't find in the article was an explanation (or even a hypothesis) for how this mechanism evolved. One of the things I find most fascinating about evolution is how seemingly irreducible complexity in nature always turns out to have a some path of mutations and adaptations that led to the current state. For instance, the canonical example of 18th century teleology, the eye, was touted as being so unimaginably complex that there's the only conceivable explanation for its existence was design, yet today we have a clear picture of how that organ arose from simple photorecptive cells. My guess in this instance? The friction plates that their ancestors have and the other species have got bumpy, then they got more bumpy, then they interleaved.
E.g., avoiding ivory tower planning and instead using empirical, in-the-wild A/B testing.
Mutation and genetic drift play a role in evolution, but are not the sole source of changes.
A perfect example is the eye. An organ of great complexity, but one that is very easily explained by logical evaluation, as well as existing living creatures and fossils: http://www.youtube.com/watch?v=Nwew5gHoh3E
If you're a software engineer, I hope you understand how procedural systems and algorithms can transform data and functions. Similar processes take place via chemistry and biological interaction. Conway's Game of Life is a good example of a simple system giving rise to complex interaction and patterns.
Complex beauty can arise from the interaction of systems, but if you say to yourself that it "must have been engineered by something greater than me", you settle in your mind, and shortcut around critical thinking and never progress toward understanding. And that's a great, great shame.
I agree with you about patterns and mathematics - also beautiful, but cold (sorry, best I can explain it).
But when we see a complex physical problem, and then see a nicely designed and implemented real-life solution - there I think my "engineered" theory has as good a chance at being correct as does the theory that says it just sprang up from 100 million years of evolution and random mutations (both of which I agree do occur).
You may think that it is a necessary defect, but the squid eye, which evolved independently to end up almost identical to its vertebrate counterpart doesn't have it. The nerve fibers and blood vessels run behind the retina.
When I'm told the algorithm is really just a random collection of instructions, assembled through an unguided process, that just happens to be work...that strains belief. But even accepting that, I'm still left with instructions, language, symbols, and interpretation. And these can only be produced by intelligence.
Something as simple as the characters we use to write code means nothing unless meaning is ascribed to them, and meaning can't arise from a strictly meaningless process (evolution, chemical interactions, etc). I think the simpler, and truer explanation for why these systems appear engineered, is because they are.
1. This geared creature must be considered part mechanical. A cyborg, if you will.
2. A "gear" is no longer (and was never) a "mechanical" device, but instead an organic one. Using gears is no longer (and was maybe never) doing mechanics.
3. Whether something is mechanical or organic depends on the process which created it. This is the "colored bits" or "patent" view. (If I build something using intuition instead of reason, am I no longer doing mechanics?)
4. A gear is no longer (and was never) either mechanic or organic, and is simply a physical process. The whole "mechanical" and "organic" division is a false dichotomy.
Bones and joints basically act as levers and pivots so why can't gear like body parts be found in other lifeforms.
6. Creatures like this shake my faith in evolution.
Why? It's easy to imagine a couple of touching pieces in the ancestor of the issid that aided in synchronizing the jumping mechanics.
Over time, mutations in those touching pieces interlocked more firmly until they resembled what we think of as gears. There was pressure on those mutations to proceed toward gears since the gear mechanism is a potentially successful one for achieving the goal of survival through jumping very far, very quickly.
Evolution has yielded some astoundingly more impressive structures. Take a look at this video that explains your own muscle contractions:
http://www.youtube.com/watch?v=gJ309LfHQ3M
The fact that our brains can pattern match the semblance of gears in the issid with gears that we created is a much more impressive development than the gears of the issid themselves.
Being able to jump quicker than your less-able siblings could convey a huge evolutionary advantage. This quickly weeds out the less-able and strongly encourages this kind of structure to develop once the process has started for whatever reason.
Over time, mutations in those touching pieces interlocked more firmly until they resembled what we think of as gears.
If this were the case, would you not expect to observe these evolutionary steps in other organisms today? As noted in the article:
...there are many jumping insects like the issus... [though] most other bugs synchronize the quick jolt of their leaping legs through friction...
If there are "many jumping" insects, how does it come to be that only a single specie (that we know of, granted) that has evolved this feature, and why have we not observed others undergoing the evolutionary process that could/would yield them in others?
Because evolution isn't planned, it involves selection from randomly[1]-occuring variations each of which has a extremely low probability. Certainly, we see some some traits that arise independently in different populations in different places with similar traits and are preserved and develop in similar ways, but the fact that a feature that contributes to fitness arises uniquely in one place is far from surprising.
[1] well, really, many of the processes are highly-chaotic more than random, but that's beside the point here.
I grant you all but a feature that contributes to fitness arises uniquely in one place is far from surprising. First, I'm not a biologist and have not studied evolution/evolutionary processes as much as I would like to, but it's hard to agree with that statement. Why exactly is it not surprising? In the over one-million insect species estimated to exist[1], of which some percentage (won't even try to guess) have some evolutionary jumping mechanism, it seems at least mildly surprising that we've never observed at least similarly structured creatures.
[1]: http://en.wikipedia.org/wiki/Insect#Distribution_and_diversi...
Its not surprising that some survival-valuable features (especially when they fulfill a function for which there are other mechanisms) arise and are preserved and further developed only once, since them arising in a species in which they are survival-useful is a matter of chance, as is their preservation.
So, its not surprising that features we haven't seen in other species is continue to be discovered. Its remarkable enough to be newsworthy and interesting, but not something that fundamentally challenges the expectations and understandings we have from basic understanding of evolution.
Indeed. In fact, what I find more surprising is that some non-trivial adaptations have developed more than once. Flight for instance evolved four separate times (bugs, birds, bats, and now-extinct pterosaurs all fly[flew], but none of them share a common ancestor that could also fly.) I find that simply remarkable. Really drives home the massive timescales that are involved.
Surely, "now-extinct pterosaurs", not "non-extinct pterosaurs", unless I missed some very newsworthy discovery.
Because:
- the designer is not that clever,
- the designer likes to play with its creatures,
- the designer is not alone,
- the designer forgot to update its creations,
- or simply because she does not care.
Some designed Bengal Tigers, and others designed Aye Ayes.
Why? Just because one life form developed a feature doesn't mean that other life forms will have it.
As the article mentioned, there are other solutions to the same problem that other insects evolved. Probably the gears solution is statistically less likely.
Then again, if this was just discovered, how hard have we really been looking?
If there was evolutionary pressure to produce an integrated circuit, some form of one would undoubtedly evolve eventually.
Microprocessors (aka, brains) seem pretty straightforward though. Even a little coordination and planning is better than none.
On the other hand, I don't think I would call the loops that fishing line passes through along the length of a fishing pole "pulleys".
I guess I'd say that block and tackle is not common, and neither are "wheeled pulleys", but "friction pulleys" are.
Alternatively, shoelace eyelets are pulleys ('block and tackle' in fact) , but describing them that way seems odd.
Very well stated.
This is not a false dichotomy, nor is it a true dichotomy, but a misunderstanding of just what concepts like "mechanical" are.
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 similar, near-standard components, yet ultimately giving rise to consciousness.
...and the civil engineer gets the blame for routing a hazardous waste pipeline through a recreational area.
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?
http://threepanelsoul.com/2010/07/05/on-design-by-committee/
Many commenters seemed to think I was asking a question of which of the possibilities was the correct one, and (correctly) answered that the fourth one was correct. This was not my intent, I merely wanted people to reflect on the possibilities and come to their own conclusion.
Everything that moves can be considered mechanical.
There is no "mechanical" vs "organic" division. It doesn't even make sense.
The terms you're looking for are 'natural' and 'artificial,' as in "of nature" and "of artifice (created by man)." These are natural gears, which are so surprising because we'd long assumed the gear itself to be an artificial concept.
Notes:
1) I don't use 'artificial' in the more modern connotation, meaning roughly "fake" or "not genuine." Rather, I use 'artificial' in the original sense of the word, deriving from the Latin artificium, or 'craft.'
2) To be fair, 'mechanical' has increasingly taken on a connotation of artifice or man-make ever since the Industrial Revolution (cf. 'mechanic,' 'mechanism'), but in the truest sense of the word, this is not necessarily the case.
3) My semantical nitpicking aside, I admit you raise some interesting points. I want to acknowledge that.
How is that blurry?
> 'Organic' is a similarly blurry category
I thought "organic" was restricted to carbon chemistry. Seems pretty specific to me.
> The terms you're looking for are 'natural' and 'artificial,'
It may be that his choice of words conflicts with his meaning, or at least conflicts with your interpretation of his meaning, but doesn't make his original word choices less specific in their inherent meaning.
> 'mechanical' has increasingly taken on a connotation of artifice or man-make
Maybe I'm too far down the rabbit hole, but the Industrial Revolution hadn't even occured to me. There is plenty of mechanical action in the human body, and those have certainly been solids long before Latin came around.
"It may be that his choice of words conflicts with his meaning, or at least conflicts with your interpretation of his meaning, but doesn't make his original word choices less specific in their inherent meaning."
Not sure I understand what you're saying here. My point is that the words he used were used to frame a false dichotomy, and that the use of more precise words for what (I interpret) he was trying to get at would have improved his thought experiment. As I mentioned, I think he raised some good points, regardless of word choice.
As I also mentioned, "mechanical" (literal) and "organic" (literal) do not form a dichotomy; they are not mutually exclusive categories. Surely you would agree here, as you seem to be saying as much.
"Maybe I'm too far down the rabbit hole, but the Industrial Revolution hadn't even occured to me. There is plenty of mechanical action in the human body, and those have certainly been solids long before Latin came around."
Again, see my point about connotation vs. denotation. The IR is roughly when connotations about the word "mechanical" started muddying the waters. (We should note that the ancient Greeks, from whom the word 'mechanics' descends, were certainly prolific engineers in their own right -- but they were careful not to blur the lines the way English has).
At any rate, I brought up this point simply to give the OP some credit, i.e., that I can see how it's easy to use the word "mechanical" to refer to "artificial," given that modern-day connotation is heading in that direction. This was a side point at best, though, and not the focus of my post.
I apologize to you, and to the OP, and to any unfortunate readers of this discussion, for dragging us down what is indeed a rabbit hole.
"Organic" has an older and still more widely encountered use, roughly, "relating to or derived from living organisms".
"organic" as pertaining to carbon chemistry is chemistry jargon that derived from the general use because of carbon's key role in biology.