[HN Gopher] Feathers are one of evolution's cleverest inventions
       ___________________________________________________________________
        
       Feathers are one of evolution's cleverest inventions
        
       Author : sohkamyung
       Score  : 277 points
       Date   : 2024-04-17 12:17 UTC (1 days ago)
        
 (HTM) web link (www.scientificamerican.com)
 (TXT) w3m dump (www.scientificamerican.com)
        
       | matrix2596 wrote:
       | archive link plz
        
         | xanny wrote:
         | Just append archive.is/ to the beginning of the url. Chances
         | are, it is already archived.
         | https://archive.is/https://www.scientificamerican.com/articl...
        
           | swores wrote:
           | Or save a bookmark in your browser and edit its destination
           | to be this Javascript bookmarklet to let you load the
           | archive.is version of any URL you're currently on without
           | even needing to remember the domain or type anything:
           | javascript:void(location.href='https://archive.is/?run=1&url=
           | '+encodeURIComponent(location.href))
           | 
           | Or version for IA's Wayback Machine instead:                 
           | javascript:void(window.open('https://web.archive.org/web/*/'+
           | location.href))
           | 
           | (The archive.is one takes you to it in the same tab, while
           | the wayback machine one opens a new one - because personally
           | I use the former when I can't load a page, so don't need that
           | tab kept open, and use the W.M. for comparing current to old
           | versions of the page. But it should be fairly self-
           | explanatory how to swap one URL with the other if you prefer
           | it differently.)
           | 
           | Or this more complicated version of the Wayback Machine one,
           | which if you click while on an empty tab will instead give
           | you an alert with a text field in which to type or paste
           | whatever URL you want to look up:                 javascript:
           | (function()%7Bif(location.href.indexOf('http')!=0)%7Binput=pr
           | ompt('URL:','https://');if(input!=null)%7Blocation.href='http
           | ://web.archive.org/web/*/'+input%7D%7Delse%7Blocation.href='h
           | ttp://web.archive.org/web/*/'+location.href;%7D%7D)();
        
             | jmckib wrote:
             | Thank you, that's so convenient!
        
       | hubrix wrote:
       | https://archive.is/20240416202627/https://www.scientificamer...
        
       | isolli wrote:
       | Pet peve: I don't like superlative descriptions. They're often
       | counterproductive, because they call for a rebuttal.
       | 
       | How many other evolutionary inventions have you included in the
       | comparison? What comparison criteria have you used?
       | 
       | I would prefer: "Feathers are an incredibly clever invention of
       | evolution."
        
         | rsynnott wrote:
         | Well, as somebody who likes complaining, I don't like your new
         | title either; evolution doesn't 'invent' anything, and
         | anthropomorphising it just confuses people (see also generative
         | ai, grumble mutter).
        
           | isolli wrote:
           | Oh, I agree! But I did not want to make more than one change
           | at a time ;)
        
           | cies wrote:
           | > evolution doesn't 'invent' anything
           | 
           | Really? I think it kind of does invent. Trial and error. Back
           | propagation. Mutation. Some randomness at conception. Sure
           | it's a personification, but not a bad one.
        
             | thfuran wrote:
             | Evolution doesn't do back propagation.
        
               | arrow7000 wrote:
               | The evolutionary fitness of a particular adaptation helps
               | spread the genes that causes the adaptation. I think
               | backpropagation is a very apt description for that
               | phenomenon
        
               | klyrs wrote:
               | That's propagation.
        
             | owlstuffing wrote:
             | There is zero science to back that up, natural selection
             | [?] evolution.
        
         | RicoElectrico wrote:
         | I thought "one of" is a weasel qualifier here?
        
           | isolli wrote:
           | Indeed, but it still unconsciously invites controversy (in my
           | opinion) -\\_(tsu)_/-
        
         | Ensorceled wrote:
         | > Pet peve: I don't like superlative descriptions. They're
         | often counterproductive, because they call for a rebuttal.
         | 
         | Pet peeve: People who HAVE to rebut things like superlative
         | descriptions. They're always counterproductive, because
         | literally nothing actually called for a rebuttal. It clutters
         | up the conversation much worse than "well, actually"
         | corrections.
        
           | thfuran wrote:
           | >literally nothing actually called for a rebuttal
           | 
           | Aside from the initial false claim, you mean?
        
             | Ensorceled wrote:
             | > Aside from the initial false claim, you mean?
             | 
             | Well, yes, we're talking about the superlative in the
             | title. Everything else might be nonsense and is fair game.
        
         | gromneer wrote:
         | i don't like people who spam "well ackkktually" and make it so
         | entire categories of phrases need to be eliminated to appease
         | their neurosis.
        
           | Ensorceled wrote:
           | It's a form of tone policing ... " _I_ don 't like
           | superlatives so _you_ don 't get to use them."
        
       | ChrisMarshallNY wrote:
       | That's a great breakdown of feather technology. TIL...
        
       | gumby wrote:
       | Wow, what an interesting article, not all about feathers. There's
       | so many genetic mysteries about skin appendages still to be
       | uncovered e.g. in humans, how do nails and hairs manage to grow
       | only in one direction (and perhaps even more remarkable, always
       | so).
       | 
       | I was drawn to this side point though: the _microraptor_ has
       | _four_ wings. Not like a dragon, of course, which has to be an
       | insect, but an ordinary quadruped that used all four limbs to fly
       | (compare that to mammals with a membrane between the forelimbs
       | and hind limbs on each side). I imagine it must have looked like
       | an F-35 when flying.
       | 
       | Seems like it turned out to be optimal to stick to two, not just
       | for terrestrial mobility, but due to the (bidirectional!)
       | optimization of the wishbone and the chest musculature. It's
       | probably hard to get enough power into the dual-mode hind limbs.
       | Sadly the Wikipedia article on the _microraptor_ doesn't explore
       | this.
        
         | cies wrote:
         | > in humans
         | 
         | Nails are a much older "invention of evolution" than humans: so
         | we have to investigate there...
         | 
         | > how do nails and hairs manage to grow only in one direction
         | 
         | Like all things evolution: nails that grow backwards to not
         | have an advantage (prolly a disadvantage), where nails that
         | grow forwards have an advantage (climbing, clawing,
         | scratching).
        
           | inglor_cz wrote:
           | "nails that grow backwards to not have an advantage (prolly a
           | disadvantage), where nails that grow forwards have an
           | advantage (climbing, clawing, scratching)."
           | 
           | That still doesn't describe the underlying mechanism of the
           | growth itself.
           | 
           | Looking at the work of Dr. Michael Levin regarding electric
           | communication of cells, I tend to believe him that the main
           | factor in actually creating tissues in their intended,
           | correct shape, is incessant electric chatter among individual
           | cells.
           | 
           | An interesting corollary would be that cancer = cells that
           | don't cooperate/communicate with their neighboring cells
           | anymore.
        
             | pfdietz wrote:
             | Another interesting question is how development
             | distinguishes left and right. As I understand it, there's a
             | small object that develops that has cilia in a tilted
             | configuration. The rotation of the cilia causes a flow of
             | fluid to one side that is determined by the sense
             | (clockwise or counterclockwise) of the cilia's rotation.
             | That flow is sensed and sets off signals that drive
             | development.
             | 
             | Where does the rotational sense of cilia come from? From
             | the stereochemistry of proteins, and therefore from amino
             | acids. The left-vs-right handedness of the base chemistry
             | of life is exploited to get a macroscopic signal.
        
               | inglor_cz wrote:
               | Wow, you amazed me. That is a journey of several orders
               | of magnitude.
        
               | throwway120385 wrote:
               | That journey of orders of magnitude is the journey of all
               | life on Earth from its genesis to today.
        
           | VeninVidiaVicii wrote:
           | I hear this kind of "it exists because it has to exist" thing
           | from non-bioscience types a lot. Essentially, this is just a
           | tautological statement.
        
             | morley wrote:
             | I don't read "it exists because it has to exist" in the
             | parent's statement. They're saying that there's an
             | advantage one way and a disadvantage another, and evolution
             | favors advantages. I wouldn't characterize a statement like
             | that as a tautology, and I don't think the author deserves
             | your dig for it.
        
               | VeninVidiaVicii wrote:
               | In my opinion there's a general fundamental
               | misunderstanding on the purpose of theories. I see it all
               | the time -- attempts to explain why something is useful
               | simply because it exists (re: popular science evolution).
               | There are loads of suboptimal traits that are
               | counterbalanced by something else.
        
             | bane wrote:
             | Tautologies may be unsatisfying, but there's nothing
             | specifically wrong with them.
        
               | VeninVidiaVicii wrote:
               | It is what it is.
        
           | moi2388 wrote:
           | Yeah that's not how it works. Fitness is not determined for
           | every single attribute.
           | 
           | For example, observation A might be maladaptive, but it is
           | caused by gene B which also causes observation C, which does
           | provide an advantage.
        
         | marcosdumay wrote:
         | > Seems like it turned out to be optimal to stick to two
         | 
         | You can't conclude that. Evolution is noisy and random.
         | 
         | Besides, birds are not unambiguously the most optimized flying
         | vertebrates around.
        
           | freedomben wrote:
           | > You can't conclude that. Evolution is noisy and random.
           | 
           | You're correct that you can't conclude that evolution is
           | perfection/optimized, but it's also not correct to say it is
           | random. The genetic variation is random, but natural
           | selection is very much _not_ random[1][2].
           | 
           | [1]: https://evolution.berkeley.edu/misconceptions-about-
           | natural-...
           | 
           | [2]: See Number 7.
           | https://www.pbs.org/wgbh/evolution/library/faq/cat01.html
        
             | vcg3rd wrote:
             | Regardless, it doesn't have agency and isn't clever.
             | Personally I belive in a Designer, but since middle school
             | I've been bewildered by the way evolution is almost always
             | presented, outside of rigorous scientific literature, as if
             | there is agency, intelligence and intent behind it.
             | 
             | I don't have a problem with that, but materialists don't
             | have that luxury and use language in bad faith when do it.
        
               | philosopher1234 wrote:
               | Evolution in humans, from an atheist perspective, is
               | consistent with the idea of a designer: humans are the
               | designer.
               | 
               | Sexual selection in humans is a psychological phenomenon,
               | and it's subject to all of our most hifalutin ideas.
               | 
               | You have an opinion about what "god" wants and express it
               | through sexual selection, thus influencing our collective
               | evolution in that direction.
        
               | stuaxo wrote:
               | But why do they want what they want, and how much agency
               | is there really anyway ?
        
               | TeMPOraL wrote:
               | Also ironically, by the time we became able to conceive
               | of and communicate about such ideas, natural evolution
               | has long stopped being the driving force behind how
               | humans and human groups look and grow and evolve.
        
               | throwway120385 wrote:
               | It's hard to explain an animistic force of nature to
               | another human without using words that imply agency. It
               | feels like our language and our ways of thinking are
               | hard-wired to see everything through that lens because we
               | have agency. It's like a fish trying to imagine what it's
               | like to be outside of water.
        
               | 48864w6ui wrote:
               | Bruce Lee's injunction "be like water" probably means
               | don't overcomplicate with agency and opposed
               | consciousnesses, just evolve the lagrangian (towards
               | victory).
               | 
               | (Speak not of the relevant XKCD)
        
               | Yeul wrote:
               | Didn't Darwin write a book that did just that?
        
               | renewiltord wrote:
               | Dude, that's just the language. "Water wants to flow
               | downhill". It's a model, man. Everyone learns this pretty
               | quickly. I don't get how this position is so popular on
               | HN/Reddit. The language is giving you tools to model the
               | world.
               | 
               | "The water doesn't want anything. It's just the laws of
               | gravity."
               | 
               | Intelligence comes from being able to efficiently
               | compress highly predictive models. Any computational
               | mechanism that is unable to do this is a low-grade
               | intelligence. If you need the whole thing spelled out
               | carefully for you, you're NGMI.
        
               | gumby wrote:
               | You might enjoy Dennett's "The Intentional Stance" for
               | some enlightening exploration of this metaphor, e.g. "The
               | thermostat tries to keep the temperature between 67 and
               | 69" not only makes sense but is a useful way to think of
               | it even when we don't believe the thermostat has agency.
        
               | TehShrike wrote:
               | I've observed this as well. People who believe in
               | evolution can't seem to stop themselves from using
               | "intelligent design" language to anthropomorphize
               | evolution.
        
               | prerok wrote:
               | I agree with the sentiment. I also heard of some books
               | that say stupid things like humans have not yet reached
               | the maximum of human evolution.
               | 
               | Of course we have not reached the end of our evolution.
               | That will exist only when we are all extinct.
               | 
               | As for the direction... that is something else. Maybe we
               | will evolve into higher intelligence, but as the Dick's
               | story "The Golden man" or "Idiocracy" show, is the
               | intelligence really the driving force of today?
        
               | mulmen wrote:
               | > is the intelligence really the driving force of today?
               | 
               | Yes, certainly. More than anything intelligence
               | differentiates us as a species.
        
               | prerok wrote:
               | I don't agree. Women, in general, don't find men
               | attractive because of intelligence. It's other factors
               | more like, whether their life is in order, they are fit,
               | or the classic, if they are symmetrical.
               | 
               | So, we are visually, materiallistically oriented. Not
               | all, of course, but evolution works on population size,
               | not exceptions. Exceptions only come into an overbearing
               | effect on cataclysmic events.
        
               | TeMPOraL wrote:
               | It's not that kind of intelligence that matters. Don't
               | think in terms of being good at chess, poetry, or
               | multiplying numbers in your head. Think wheel, writing,
               | domestication, agriculture, petrochemical engineering,
               | nuclear weapons, computers, genetic engineering.
               | 
               | Our intelligence is what allows us to acquire and improve
               | new adaptations without having to change our own
               | genetics. We're able to change living environments and
               | adapt to them multiple times in a single life span, and
               | we went from basic language to walking on the Moon much
               | faster than evolution is able to make meaningful changes
               | through natural selection. It takes however many million
               | years for a species to grow fur to adapt to cold climate;
               | it took a spear for us to adapt by stealing other
               | animals' fur, and couple hundred years to figure out how
               | to make synthetic ones at scale. In that time, we adapted
               | to almost every environment on the planet.
               | 
               | Intelligence very much _is_ the driving force behind
               | humanity.
               | 
               | EDIT: and we're also beating natural selection from the
               | other end - modern medicine allows many people to live
               | and reproduce, who without it would've died from genetic
               | diseases. We're very good at denying the "fitness"
               | criteria nature uses.
        
               | bdamm wrote:
               | While I agree with your general slant, it's not correct
               | to say that evolution can't act quickly. Evolution can
               | act, and does act, slightly faster than a single
               | generation. Populations change rapidly, and the success,
               | failure, life and death of individuals and their guiding
               | behaviors, change with it. The introduction of online
               | dating, for example, has already caused evolutionary
               | changes in our species. Only time can tell if these
               | changes are going to last. Just because we haven't yet
               | generally grown thumbs adapted for interacting with
               | iPhones doesn't mean that the more subtle changes haven't
               | happened.
        
               | Nevermark wrote:
               | As humans we do things for teleological reasons. Meaning
               | we can say we did X in order to accomplish Y.
               | 
               | Ascribing teleological explanations to evolution is
               | technically wrong, since it doesn't look ahead.
               | 
               | However, it does something very similar. Our brains
               | process competing options, from plausible to nonsensical,
               | before selecting an action, partly in sequence
               | (ideation), but also in parallel (competition
               | processing).
               | 
               | Evolution tries many options in parallel and sequence
               | too. Just by actually doing them and then selecting which
               | of those choices to keep repeating (better survival), and
               | those to forget (extinction of genes, clusters of genes,
               | or whole species).
               | 
               | So over longer time periods, it acts very teleologically.
               | A kind of reverse teleologic by hindsight.
               | 
               | The same is true for the "brilliance" of this teleology.
               | Evolution tries so many things, that it can solve very
               | difficult problems in very novel ways.
               | 
               | Is that "intelligence"? Our casual usage of intelligence
               | isn't defined precisely enough to say one way or another.
               | 
               | One person would say evolution is blind, and in the short
               | run it is. But another person might point out that
               | evolution is anything but blind. It is an epic version of
               | Edison's lab, where millions or billions of false
               | solutions are continually tried and ruled out, to find
               | each new fitness enhancement.
               | 
               | It relentlessly experiments and follows the "data".
               | 
               | On longer timescales, evolution is effectively
               | teleological, highly creative and very intelligent.
               | 
               |  _And all three aspects compound over time, just like
               | human learning and research_ , because evolution doesn't
               | just find new features, but new abstractions and
               | modularity. Such as flexible reusable gene systems for
               | encoding body parts, epigenetic reuse of features in
               | different kinds of cells for different purposes or
               | triggered and "run" by different conditions, nervous
               | systems, etc.
               | 
               | Thus evolution "learned" to speed itself up over time,
               | letting it more rapidly optimize larger more complex
               | solutions. I.e. orders of magnitude faster creation of
               | new novel animals, than it originally took to optimize
               | the first cellular life, colonies of cells, etc.
               | 
               | Watching evolutions first billion years would not have
               | suggested that the plethora of different intelligent
               | animals, from octopus, parrot to human, would have been
               | remotely possible in the time it took. Evolution's
               | compounding meta learning created brains, our "true"
               | teleology, and its expansion into technological and
               | economic expressions of the pursuit of survival. All meta
               | extensions of evolution, found by evolution.
        
             | heresie-dabord wrote:
             | > natural selection is very much not random
             | 
             | Except where punctuated by (subjective) catastrophe.
             | 
             | But then it is not the mechanism of evolution itself that
             | is random.
        
               | prerok wrote:
               | Well, it's never random, is it? It's only random when all
               | is equal, otherwise it's biased. That's why it works.
               | 
               | Consider birds. There was a good article a few days back,
               | on why only non-toothed birds survived. Until the meteor-
               | strike, 65M years ago, all was equal and they survived
               | along-side. Until they were the only survivors.
        
               | heresie-dabord wrote:
               | The asteroid that created the Chicxulub impact came from
               | a rather random location but had a deterministic effect
               | given where it struck.
               | 
               | And here we are, with beaked birds. ^_^
               | 
               | https://en.wikipedia.org/wiki/Chicxulub_crater
        
             | Retric wrote:
             | Random doesn't mean all outcomes are equally likely, a coin
             | rarely ends up on its edge.
             | 
             | Thus evolution is often random _between local optima._
             | People's organs don't represent perfect left /right
             | symmetry but there's no particular benefit for which of the
             | two options were chosen overall. Ie swap just which lung is
             | smaller and you get lots of problems, but swap everything
             | and it all works.
        
           | m463 wrote:
           | Maybe optimized for their niche.
           | 
           | I remember reading something about bombers maybe during ww2.
           | I think if fighters were chasing them, the bombers could
           | escape because with their large wings, they could fly high
           | and slow and turn inside them.
           | 
           | the analogy being - some birds might be set up for ground
           | operations and chasing prey, others living in a different
           | ecosystem with high altitude cruising over long distances.
        
         | Hendrikto wrote:
         | Dragonflies are pretty much the best flyers among the insects,
         | and they have four wings. Maybe not directly comparable, but
         | still.
        
           | GuB-42 wrote:
           | Generally, all insects have four wings, but they are not
           | always used for flying.
           | 
           | Flies in particular are also among the best flyers, and yet,
           | they use only two of their wings for flying, the other two
           | shrank to became halteres, a sensory organ acting like a
           | gyroscope.
           | 
           | Dragonflies may be the best fliers in the insect world thanks
           | to their four independently controlled wings, but flies may
           | be the second best, and they achieved that by _losing_ two of
           | their four wings. Evolution is interesting.
        
           | meindnoch wrote:
           | Hummingirds are the best flyers among vertebrates, with only
           | two wings. They can hover very precisely, and they can also
           | fly backwards.
        
           | gumby wrote:
           | insects are so different from vertebrates (e.g. multi
           | compartment bodies thanks to how they express the HOX gene)
           | that the flying strategies are also quite different.
           | 
           | At the current level of O2 in the air I don't believe that
           | flying insects can grow as large as even a hummingbird, much
           | less an eagle.
        
         | huytersd wrote:
         | Because nails and hair are produced at a fixed site. The nail
         | itself is dead cells and do not grow.
        
           | gumby wrote:
           | That isn't the question (in a prior job I studied the
           | physiology of the nail unit). Most cells don't normally have
           | an orientation, so you'd think that thefollicle would push
           | out a hair in some random direction, sometimes towards the
           | outside world and sometimes in the direction of your bones.
           | 
           | Obviously they don't (!) but the question is how?
           | 
           | The nail is the same: the lunula emits these keratinocytes in
           | only one direction; even more weirdly it's a planar
           | structure.
        
             | throwup238 wrote:
             | _> Obviously they don 't (!) but the question is how?_
             | 
             | Don't cells "just" orient themselves using
             | mechanotransduction [1] or am I missing something? That's a
             | bit hand wavey but since cells don't form 3d structures in
             | tissue themselves, they orient against the extracellular
             | matrix using mechanotransduction and other growth factors.
             | 
             | The development of multicellular life was essentially cells
             | learning how to orient themselves into a digestive tract.
             | 
             | [1] https://en.wikipedia.org/wiki/Mechanotransduction
        
         | ghaff wrote:
         | Not always.
         | 
         | On two different occasions, I've had ingrown toenails that had
         | to have a procedure done because, once they started ingrowing,
         | they wouldn't stop doing so. (It's still outward growth but
         | still.)
        
           | tylerchilds wrote:
           | i've had those procedures-- super painful. i've ended up
           | doing surgeries to cauterize the roots to prevent the ingrown
           | growing direction.
        
             | ghaff wrote:
             | Wasn't my experience FWIW. (Mostly commenting so others
             | won't necessarily avoid.)
             | 
             | Just an in-office procedure using some local anesthesia and
             | acid I think. The first time the whole cycle went on for
             | months while I was regularly going to the podiatrist
             | because of a fairly severe foot fracture of the same foot
             | which may or may not have been connected.
             | 
             | This last time--a good 15 years later symmetrically on the
             | other foot--I was pretty much just "Let's do this" after a
             | couple times trying to just cut the toenail.
        
           | Balgair wrote:
           | For others that have had this issue too: Cut your toe nails
           | in a straight line. I used to cut them in a curved line, a
           | 'C' kind of shape. Don't do that. Cut them in a '|' kind of
           | shape. Yes, you'll have a big overhang on the edges, but give
           | your toe time to adapt.
           | 
           | I've had a few of these procedures too and it never really
           | stuck for me. Ingrown toenails kept being a problem. Then I
           | started cutting my toenails in the flat / straight '|' sort
           | of way and I've not have a problem since.
           | 
           | I figure it's worth a shout out to the few of you out there
           | that need the help. But, again, it may not work for you too.
        
             | djtango wrote:
             | My friend told me this like 15+ years ago. I was skeptical
             | but it really works. I then just use a file to take a bit
             | of the edge off until its a curve
        
             | aqfamnzc wrote:
             | Wow, amazing. Why does this work? I would think that the
             | nail bed has no knowledge of what the end of the nail is
             | shaped like.
        
               | Kubuxu wrote:
               | It keeps the side from curling in and causing the
               | irritation/cut that results in what we call ingrown
               | toenail.
        
               | londons_explore wrote:
               | Ingrown toenails basically don't happen in cultures where
               | people don't wear shoes.
               | 
               | I suspect the cause is socks or shoes pushing against the
               | skin at the end of the toe, causing it to grow
               | incorrectly over many months.
               | 
               | An untrimmed nail pushes any sock/shoe away, solving the
               | issue.
        
           | gumby wrote:
           | Despite the terminology, "ingrown" doesn't mean the nail
           | grows in the wrong direction. The lunula continuously emits
           | keratinocytes in a single direction; these form both the nail
           | bed and the nail itself.
           | 
           | The "ingrown" phenomenon occurs well after the nail has
           | formed (it's getting pushed out from the lunula end) and is
           | due to a combination of your toe's (hallux I assume)
           | ideosyncratic geometry and environmental conditions, likely,
           | as another commenter pointed out, how you innocently cut your
           | nail.
           | 
           | Sorry for the pedantry but when I worked in drug development
           | I used to research the nail unit, which, it turns out, few
           | people do.
        
             | atombender wrote:
             | The most interesting thing I've learned about nails is that
             | they're now thought to be part of an organ -- the enthesis
             | organ [1], which is the tissue structures around the site
             | where the tendon attaches to the bone. This is relevant to
             | spondylarthropathies, some of which show up as nail changes
             | many years before enthesitis occurs.
             | 
             | [1] https://www.enthesis.info/anatomy/enthesis_organ.html
        
         | snarfy wrote:
         | The hair on your head grows indefinitely. The hair on your arms
         | and legs grows to a certain length and then stops. You can
         | shave it off, but it grows again, but only to that same length.
         | 
         | How does the hair on arms and legs 'know' how long it is?
        
           | m463 wrote:
           | Does it drop off after a certain time period (= length)?
        
           | throwaway5752 wrote:
           | https://www.washingtonpost.com/news/speaking-of-
           | science/wp/2...
           | 
           | Different anagen phase durations.
        
             | harshaxnim wrote:
             | Still doesn't answer - How does the follicle know that I
             | cut my hair and needs to grow again to that length?
        
               | mkaic wrote:
               | IIUC, it doesn't. Hair grows for a certain time period,
               | falls out, and regrows. The follicle has no knowledge of
               | the length of the hair it is producing, it is simply on a
               | grow-stop-shed cycle with a certain period.
        
               | guerrilla wrote:
               | So hairs are actually excretions, like sweat and shit.
        
               | bdamm wrote:
               | There are possible physical answers; it could be lack of
               | inertia on the hair triggers growth. It could be that
               | when you rub your arm, an action as innocent as a yawn,
               | you are also informing the growth of hair. Could it be as
               | simple as looking at your hair or knowledge of shaving
               | causes a subconscious trigger? We already know that these
               | high level shortcuts into low level processes exist
               | (Pavlov's dog anyone?)
        
               | someotherperson wrote:
               | It doesn't know. Hair cycles are constant. If you didn't
               | cut it, it would eventually fall out as it is replaced by
               | another hair. It grows to the point where the epithelial
               | column contracts and starts forcing it out. This is based
               | on environment, nutrition and genetics and varies from
               | person to person and is affected by everything from
               | stress to blood flow.
               | 
               | You can observe this on many people by looking at hair
               | miniaturization of people who have MBP or similar -- the
               | follicle constricts in size and the resulting hair that
               | comes out is progressively shorter in length and diameter
               | until the follicle is so constricted that it no longer
               | produces hair.
        
           | nektro wrote:
           | and then other parts of skin know not to grow hair at all!
        
         | heresie-dabord wrote:
         | > hatching ground in Alaska to its wintering ground in Tasmania
         | 
         | According to simulations of plate tectonics, these two
         | locations would have been somewhat closer... 100m years ago.
        
       | andrelaszlo wrote:
       | > The flat, broad, flight-enabling feathers we see across most of
       | the wings and much of the body surface of living birds are called
       | pennaceous feathers. (Fun fact: these are the feathers people
       | used to make into quills for writing, hence the word "pen.")
       | 
       | I get the author's point, I think, but the etymology of "pen"
       | according to wiktionary.com:
       | 
       | > From Middle English penne, from Anglo-Norman penne, from Old
       | French penne, from Latin penna ("feather"), from Proto-Indo-
       | European _peth2r ~ pth2en- ("feather, wing"), from_ peth2- ("to
       | rush, fly") (from which petition). Proto-Indo-European base also
       | root of *petra-, from which Ancient Greek pteron (pteron, "wing")
       | (whence pterodactyl), Sanskrit ptrm (patram, "wing, feather"),
       | Old Church Slavonic pero (pero, "pen"), Old Norse fjodr, Old
       | English feder (Modern English feather);[1] note the /p/ - /f/
       | Germanic sound change.
       | 
       | So pens aren't called pens because we used _pennaceous_ feathers,
       | but because they were made of _feathers_ , period. At least
       | that's how I get it.
       | 
       | "Pennaceous feather" is a funny term too, then, meaning something
       | like "featherlike feather"?
        
         | 082349872349872 wrote:
         | ...and penknives were originally the small blades one used for
         | trimming pennaceous feathers into writing-pens.
        
         | gruez wrote:
         | The article has another factual error as well:
         | 
         | >covering 8,425 miles without taking a single break. For
         | comparison, there is only one commercial aircraft that can fly
         | that far nonstop, a Boeing 777 [...]
         | 
         | The Boeing 787 and the Airbus A350 have ranges exceeding that,
         | with ranges of up to 8,790 mi and 11,163 mi respectively,
         | depending on the variant.
         | 
         | https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Specific...
         | 
         | https://en.wikipedia.org/wiki/Airbus_A350#Specifications
         | 
         | edit:
         | 
         | Turns out there's even more aircrafts that exceed that range.
         | 
         | https://en.wikipedia.org/wiki/Airbus_A330neo#Specifications
         | 
         | https://en.wikipedia.org/wiki/Airbus_A380#Specifications_(A3...
         | 
         | https://en.wikipedia.org/wiki/Airbus_A340#Specifications
        
         | corpMaverick wrote:
         | In Spanish. Pen=Pluma. Feather=Pluma.
        
           | thaumasiotes wrote:
           | In Mandarin Chinese a pen is Bi , obviously derived from the
           | word for a paintbrush, Bi . Feathers don't come into it -
           | Chinese is traditionally written with a paintbrush - but the
           | pattern is the same.
        
         | thaumasiotes wrote:
         | > "Pennaceous feather" is a funny term too, then, meaning
         | something like "featherlike feather"?
         | 
         | I'd probably render it as more like "typical feathers" or
         | "standard feathers". Note that "typical feathers" and "feathery
         | feathers" mean the same thing, but one is perfectly normal
         | phrasing and the other isn't.
        
         | busyant wrote:
         | > from Latin penna ("feather")
         | 
         | Also in Italian. Although I believe penna can also mean the
         | more modern "pen."
         | 
         | Penne pasta is basically plural of this.
        
       | jeremiahbuckley wrote:
       | Excited to anticipate next-gen airplanes with slotted wingtips
       | and their vanes controlled by AI for optimal performance.
        
         | mhb wrote:
         | Also the new swimsuits inspired by penguin feathers.
        
           | pfdietz wrote:
           | Props for ships with knobs inspired by whale flukes.
        
       | nyc111 wrote:
       | It may be misleading to look at only to the design of the
       | feather. Flight and such a long and sustained flight can only
       | happen because of the sophisticated programming. Evolution must
       | be a great programmer too.
        
         | zelphirkalt wrote:
         | One with lots and lots of time on their hand and countless
         | trial and error, and parallel projects.
        
           | umvi wrote:
           | > and countless trial and error
           | 
           | Is it countless though? Earth is "only" 4.5 billion years old
           | with life appearing "only" 800 million years later, which
           | seems pretty short for something chaotic and unorganized to
           | self-organize into the nearly unfathomable sophistication we
           | have now. Of course, humans are bad at grokking large
           | numbers, and I might be too biased as a God fearing man... to
           | be clear I don't deny the realities of evolution, but I
           | currently tend to believe that as far as
           | abiogenesis/evolution goes, life was "seeded" in some way on
           | the planet, i.e. given a head start vs arising spontaneously
           | from primordial soup within 800M years. I realize that this
           | belief doesn't really contribute anything to the scientific
           | discussion, just musing that 800M years to create the initial
           | life seed doesn't seem that long considering we use super
           | computers to simulate trillion+ iterations of various models
           | and have failed to observe similar phenomenon in terms of
           | self-organization without outside influence.
        
       | hammock wrote:
       | I first thought the headline was "Fathers are one of evolutions
       | cleverest inventions". To which I agree
        
       | jcims wrote:
       | I'd say DNA is one of evolution's cleverest inventions, buuut. xD
       | 
       | *ducks*
        
         | wongarsu wrote:
         | Two things can each be one of evolution's cleverest inventions
        
           | xandrius wrote:
           | So you're saying that two can be one?
           | 
           | 2 = 1 proven?
        
             | daveguy wrote:
             | They are saying "one of" does not mean the only one.
             | 
             | One of my cat's eyes is blue. One of my cat's eyes is
             | green.
             | 
             | Both can be true at the same time.
        
       | SamBam wrote:
       | Really good article.
       | 
       | I know some of the early evolutionists wondered about the
       | evolution of the feather and wing, since it seems hard to evolve
       | in a gradual way -- a _little bit_ of a feathery flap doesn 't
       | offer any advantages if it's not enough to glide on.
       | 
       | I know one of the leading theories is that they evolved to keep
       | animals warm, since they're also good insulators. Is this still
       | the main theory?
        
         | swores wrote:
         | I have no knowledge in this area, this is purely a guess and so
         | I am sharing it not to inform anyone but in the hope someone
         | who does know can tell me if I'm wrong:
         | 
         | When I thought about this in the past, I assumed they evolved
         | in sea creatures first - where even very small flaps or mini
         | wings/fins could improve hydrodynamics and/or swimming control,
         | without needing to make a single jump from useless to being
         | able to fly. But I've not looked into whether that is the case.
         | 
         | Edit to add two quotes from a quick search:
         | 
         |  _" Thus, early feathers functioned in thermal insulation,
         | communication, or water repellency, but not in aerodynamics and
         | flight."_ - https://www.britannica.com/animal/bird-animal/The-
         | origin-of-...
         | 
         |  _" Two major rival published theories are based on the roles
         | of feathers in insulating the body against heat loss and in
         | providing an aerodynamic surface for flight. However, because
         | of the lack of knowledge about the roles and ecological
         | relationships of protofeathers and of the most primitive
         | feathers, it is not possible to test strongly either of these
         | theories, or others as proposed in this symposium, against
         | objective empirical observations to determine which is
         | falsified or is the most probable"_ -
         | https://academic.oup.com/icb/article/40/4/478/101404#
        
         | sampo wrote:
         | > it seems hard to evolve in a gradual way
         | 
         | There seems to be 4 different hypotheses. So there is no
         | consensus on this question.
         | 
         | https://en.wikipedia.org/wiki/Origin_of_avian_flight#Hypothe...
         | 
         | A video about the "wing-assisted incline running" hypothesis:
         | 
         | "The Origin of Flight--What Use is Half a Wing?"
         | https://www.youtube.com/watch?v=JMuzlEQz3uo
        
       | bluishgreen wrote:
       | I read it as "Fathers Are One of Evolution's Cleverest
       | Inventions".
       | 
       | It completely made sense. I heard some research where starting
       | about 500K year ago humans started to pair bond as a way to
       | prevent mom and child mortality during and after childbirth and
       | indeed Fathers are a clever invention. So yea, feathers are cool
       | - fathers too! (for more info/reading here is a book suggestion:
       | Eve)
        
       | Gravityloss wrote:
       | If the world warms back to the saurian sauna for a few millions
       | of years, maybe mammals will not be on top of the game anymore.
       | Time to welcome our new avian overlords. Maybe they'll evolve
       | from crows. They're more optimal in so many ways anyway. Too bad
       | they won't have coal, oil or natural gas reserves to build an
       | early industrial civilization on.
        
         | holoduke wrote:
         | They have microplastics. Enough to power the new society for
         | 200 years.
        
         | wongarsu wrote:
         | But getting large amounts of copper, iron and aluminum will be
         | so much easier with all the work we have already put into
         | mining and refining it. At worst you have to invent the
         | technology to turn wood into charcoal and charcoal into coke to
         | get the fire hot enough to smelt iron. But aluminum is pretty
         | rust resistant and can be smelted with a good wood fire, and
         | avian species will likely prefer the lighter metal anyway.
        
       | Simplicitas wrote:
       | Another feature that make birds really remarkable, if not
       | mistaken, is that they take in oxygen when they inhale AND
       | exhale. Feathers are great, but a creature such as B6 still needs
       | a lot of energy to fly for 10 days straight.
        
         | delecti wrote:
         | It's more that their respiratory system is kinda circular. When
         | we exhale, there's still a bit of gas in our lungs, and that
         | reduces how efficiently we can extract oxygen. But the oxygen
         | extracting parts of a bird's lungs are more like a heatsink,
         | with air rushing past it in a consistent direction, rather than
         | back and forth.
        
           | xeonmc wrote:
           | So human lungs are piston engines whereas bird lungs are
           | turbojet engines.
        
       | luxuryballs wrote:
       | Dinosaurs were actually Chocobo
        
         | xandrius wrote:
         | Chocobo -> Dinosaurs -> Chicken
         | 
         | Checks out!
        
       | cushpush wrote:
       | is a feather a discovery or an invention? (am actual
       | philosophical inquisition)
        
         | xandrius wrote:
         | Discovery implies that it already existed before and it wasn't
         | found yet.
         | 
         | I'd say invention is closer but does seem to imply agency.
         | 
         | I think feathers _are_ the evolution here. Something evolved
         | into a feather.
        
       | Yeul wrote:
       | Doesn't clever imply a conscious designer? Not very scientific.
        
       | willturman wrote:
       | > did not land, did not eat, did not drink and _did not stop
       | flapping_
       | 
       | My understanding is that these incredible distances are
       | achievable less by "flapping" and more by leveraging small
       | adjustments to harness the incredibly powerful forces found among
       | and between air currents and waves as they traverse across the
       | ocean.
       | 
       | For example, here is an _unpowered_ remote control glider
       | achieving measured speeds of 548+! mph using nothing but natural
       | energy harnessed from wind and gravity.
       | 
       | https://www.youtube.com/watch?v=4eFD_Wj6dhk
       | 
       | https://en.wikipedia.org/wiki/Dynamic_soaring
        
         | nonameiguess wrote:
         | You see this even more in the ocean. There are sharks who,
         | being cold-blooded, have the ability to slow their metabolism
         | to very near zero and simply ride a current for thousands of
         | kilometers to entirely different parts of the globe where
         | feeding is better without expending any energy to do it. It's
         | probably why sharks have been around so long. They can be
         | extremely resistant to famine conditions.
        
         | elliottkember wrote:
         | I met that guy at a glider meetup a few months after that
         | record. That Transonic plane is huge. He managed to fit the 3m
         | wingspan into a regular car, lengthwise.
         | 
         | I never got out to Parker Mountain but those guys had great
         | stories. 100G will find the weak point on your model, often
         | explosively.
         | 
         | Also fun is pelicans surfing:
         | https://www.youtube.com/watch?v=cEFrSycTvRk
        
           | willturman wrote:
           | That pelicans surfing video is perfect - there's certainly
           | not a whole lot of flapping going on.
           | 
           |  _100G will find the weak point on your model_
           | 
           | You know, just a casual glider built to withstand 10 times
           | more gravitational force than an F-15 and 15 times more than
           | a Formula 1 car. Wild.
        
         | etangent wrote:
         | > My understanding is that these incredible distances are
         | achievable less by "flapping" and more by leveraging small
         | adjustments to harness the incredibly powerful forces
         | 
         | That is not correct. This particular bird (Bar-tailed Godwit)
         | has never been observed to "dynamically soar" nor does it have
         | the proper wing shape for that type of flight. If you ever seen
         | Godwits in the wild, you will know why, it's a flapping only
         | bird, they have no other mode of flight.
         | 
         | Albatrosses on the other hand do employ dynamic soaring and fly
         | even greater distances than Godwit does (they can
         | circumnavigate the Southern Ocean several times) although
         | albatrosses have additional advantage of being able to use
         | water for rest (Godwits cannot).
        
       | nyrulez wrote:
       | I love the science of evolution in that there's no need for an
       | underlying model for such an invention to actually verify the
       | science and the possibility of it, just that such an invention is
       | possible. Basically anything and everything is possible with
       | evolution and that doesn't really feel like science to me.
        
         | prerok wrote:
         | To me, it sounds like science at its finest.
         | 
         | Only what works, survives, regardless of the politics, i.e.
         | what others think of it.
        
       | TheMagicHorsey wrote:
       | Great article. But I hesitate to call feathers one of evolution's
       | cleverest inventions. The natural world is chock full of amazing
       | evolved engineering from the huge (the hearts of blue whales) to
       | the intricate (the brains of hominids) to the diverse (the
       | various forms of eyes from compound to pinhole, to lensed), to
       | the tiny (white blood cells). Everywhere you look there are feats
       | of engineering that would awe anyone.
        
       | DoreenMichele wrote:
       | _October 2022 a bird with the code name B6 set a new world record
       | that few people outside the field of ornithology noticed. Over
       | the course of 11 days, B6, a young Bar-tailed Godwit, flew from
       | its hatching ground in Alaska to its wintering ground in
       | Tasmania, covering 8,425 miles without taking a single break...
       | 
       | Many factors contributed to this astonishing feat of athleticism
       | --muscle power, a high metabolic rate and a physiological
       | tolerance for elevated cortisol levels, among other things._
       | 
       | Additional fun fact the article doesn't mention:
       | 
       | Birds sleep with only half their brain at a time when making
       | these long distance flights. That's why they don't doze off and
       | fall out of the sky.
        
       | dadjoker wrote:
       | Wow, they are so incredibly intricate, it's almost like they were
       | designed....
        
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