10 ms·

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

by gumby 3y ago

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 3y ago
> 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 3y ago
  "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 3y ago
    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 3y ago
      Wow, you amazed me. That is a journey of several orders of magnitude.
      - throwway120385 3y ago
        That journey of orders of magnitude is the journey of all life on Earth from its genesis to today.
  - RoyalHenOil 3y ago
    I can't speak about nails and hairs specifically, but directional cell growth is common in nature. In plants, for example, cells replicate primarily at the tip of a bud, which allows branches to lengthen directionally rather than grow out in all directions. The plant produces growth hormones, which are transported upward throughout all branches until they reach a dead end. When they reach a dead end, they stop moving and just sit there, which causes the cells at the dead end to have a greater exposure to these growth hormones. These cells bathe in growth hormones for so long that they pass the hormone-exposure threshold that triggers cell replication.
- deleted 3y ago
  [deleted]
- VeninVidiaVicii 3y ago
  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 3y ago
    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 3y ago
      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.
    - ars 3y ago
      > and evolution favors advantages The question was how, not why. Your answer is like saying "how does the eye focus light" and answering "so that you can see".
  - bane 3y ago
    Tautologies may be unsatisfying, but there's nothing specifically wrong with them.
    - VeninVidiaVicii 3y ago
      It is what it is.
- moi2388 3y ago
  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 3y ago
> 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 3y ago
  > 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-selection-and-adaptation/but-its-not-random-either/ https://evolution.berkeley.edu/misconceptions-about-natural-... [2]: See Number 7. https://www.pbs.org/wgbh/evolution/library/faq/cat01.html https://www.pbs.org/wgbh/evolution/library/faq/cat01.html
  - vcg3rd 3y ago
    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 3y ago
      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 3y ago
        But why do they want what they want, and how much agency is there really anyway ?
Hendrikto 3y ago
Dragonflies are pretty much the best flyers among the insects, and they have four wings. Maybe not directly comparable, but still.
- GuB-42 3y ago
  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.
  - jononomo 3y ago
    Another example of evolution deleting something instead of creating something. It is bizarre how many examples that people cite demonstrating evolution are actually demonstrating devolution.
- meindnoch 3y ago
  Hummingirds are the best flyers among vertebrates, with only two wings. They can hover very precisely, and they can also fly backwards.
- gumby 3y ago
  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.
  - userulluipeste 3y ago
    "At the current level of O2 in the air I don't believe that flying insects can grow as large as even a hummingbird" This got me curious. At a quick search, I found out that there in fact is at least a species of flying insect larger than (the smallest) hummingbird: https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Bee_hummingbird https://en.wikipedia.org/wiki/Bee_hummingbird The insect grows up to 7 cm in length whereas the bird can stay less than 6 cm at adulthood. No information about the insect weight though (for a proper comparison).
huytersd 3y ago
Because nails and hair are produced at a fixed site. The nail itself is dead cells and do not grow.
- gumby 3y ago
  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 3y ago
    > 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 https://en.wikipedia.org/wiki/Mechanotransduction
ghaff 3y ago
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 3y ago
  i’ve had those procedures— super painful. i’ve ended up doing surgeries to cauterize the roots to prevent the ingrown growing direction.
  - ghaff 3y ago
    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 3y ago
  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 3y ago
    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
  - 3y ago
snarfy 3y ago
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?
- throwaway5752 3y ago
  https://www.washingtonpost.com/news/speaking-of-science/wp/2016/07/19/dear-science-why-does-the-hair-on-my-head-grow-longer-than-the-hair-on-my-body/ https://www.washingtonpost.com/news/speaking-of-science/wp/2... Different anagen phase durations.
  - harshaxnim 3y ago
    Still doesn’t answer - How does the follicle know that I cut my hair and needs to grow again to that length?
    - mkaic 3y ago
      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 3y ago
        So hairs are actually excretions, like sweat and shit.
        bee_rider 3y ago
        What’s the opposite of a fun fact
        klyrs 3y ago
        Teeth
heresie-dabord 3y ago
> 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.
TravisCooper 3y ago
It's all designed. Top down, one mind. Designed. That's why it all works. Think about all the cells, and the thousands/millions of jobs they do, in perfect coordination just in your fingers or hands. It's all designed.
- RoyalHenOil 3y ago
  There is not some guy coordinating all our cells to grow and work in lockstep. It's actually just a few very simple algorithms (e.g., cells differentiation is triggered by strength of a signal, a la HOX genes) that have been very slowly refined over millions of generations of evolution. Just because the output of a system looks complicated does not mean that the input into a system is complicated.
  - concernedParty 3y ago
    The most probable scenario for inorganic matter to be arranged and organised into a living, homeostatic self replicating machine, is for a number feature complete systems (including hardware and software) to appear all at the same time. If you don't start with all of them in place, the organism dies, and fails to benefit from both time and natural selection. Even in this model there are many chicken / egg scenarios. e.g. Every cell needs a membrane to survive, but how does a membrane benefit a cell if it has no ports built in to let waste out and food in? So the wall and the access control systems must appear simultaneously, or the cell dies and does not benefit from natural selection. Another one is DNA, it's information storage, but it's inert, it doesn't do anything except be acted upon by other systems, but DNA holds the information to create those systems. So how were the systems consistently replicated before information storage systems like DNA? You probably don't care about this because you seem to be answering something he didn't suggest... But he's not saying that every cell in our bodies is being actively managed by another being, he's saying that cells have been designed to self-coordinate. Anyway, just food for thought for other readers who may also have these questions, you're not alone, and it is worth investigating because the current paradigm is in crisis and it's not worth basing your life decisions on their ideas anymore.
    - 3y ago
Intralexical 3y ago
> 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. If they fly through the same air as airplanes, you also lose efficiency wherever you have wingtips (pressure below leaks above, basically), and the rear wings can get messed up by turbulence/vortices from the front wings if you're not careful.

by gumby 3y ago

cies 3y ago

> 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 3y ago
"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 3y ago
  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 3y ago
    Wow, you amazed me. That is a journey of several orders of magnitude.
    - throwway120385 3y ago
      That journey of orders of magnitude is the journey of all life on Earth from its genesis to today.
- RoyalHenOil 3y ago
  I can't speak about nails and hairs specifically, but directional cell growth is common in nature. In plants, for example, cells replicate primarily at the tip of a bud, which allows branches to lengthen directionally rather than grow out in all directions. The plant produces growth hormones, which are transported upward throughout all branches until they reach a dead end. When they reach a dead end, they stop moving and just sit there, which causes the cells at the dead end to have a greater exposure to these growth hormones. These cells bathe in growth hormones for so long that they pass the hormone-exposure threshold that triggers cell replication.
deleted 3y ago
[deleted]
VeninVidiaVicii 3y ago
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 3y ago
  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 3y ago
    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.
  - ars 3y ago
    > and evolution favors advantages The question was how, not why. Your answer is like saying "how does the eye focus light" and answering "so that you can see".
- bane 3y ago
  Tautologies may be unsatisfying, but there's nothing specifically wrong with them.
  - VeninVidiaVicii 3y ago
    It is what it is.
moi2388 3y ago
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 3y ago

> 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 3y ago
> 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-selection-and-adaptation/but-its-not-random-either/ https://evolution.berkeley.edu/misconceptions-about-natural-... [2]: See Number 7. https://www.pbs.org/wgbh/evolution/library/faq/cat01.html https://www.pbs.org/wgbh/evolution/library/faq/cat01.html
- vcg3rd 3y ago
  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 3y ago
    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 3y ago
      But why do they want what they want, and how much agency is there really anyway ?

Hendrikto 3y ago

Dragonflies are pretty much the best flyers among the insects, and they have four wings. Maybe not directly comparable, but still.

GuB-42 3y ago
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.
- jononomo 3y ago
  Another example of evolution deleting something instead of creating something. It is bizarre how many examples that people cite demonstrating evolution are actually demonstrating devolution.
meindnoch 3y ago
Hummingirds are the best flyers among vertebrates, with only two wings. They can hover very precisely, and they can also fly backwards.
gumby 3y ago
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.
- userulluipeste 3y ago
  "At the current level of O2 in the air I don't believe that flying insects can grow as large as even a hummingbird" This got me curious. At a quick search, I found out that there in fact is at least a species of flying insect larger than (the smallest) hummingbird: https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Bee_hummingbird https://en.wikipedia.org/wiki/Bee_hummingbird The insect grows up to 7 cm in length whereas the bird can stay less than 6 cm at adulthood. No information about the insect weight though (for a proper comparison).

huytersd 3y ago

Because nails and hair are produced at a fixed site. The nail itself is dead cells and do not grow.

gumby 3y ago
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 3y ago
  > 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 https://en.wikipedia.org/wiki/Mechanotransduction

ghaff 3y ago

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 3y ago
i’ve had those procedures— super painful. i’ve ended up doing surgeries to cauterize the roots to prevent the ingrown growing direction.
- ghaff 3y ago
  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 3y ago
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 3y ago
  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
- 3y ago

snarfy 3y ago

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?

throwaway5752 3y ago
https://www.washingtonpost.com/news/speaking-of-science/wp/2016/07/19/dear-science-why-does-the-hair-on-my-head-grow-longer-than-the-hair-on-my-body/ https://www.washingtonpost.com/news/speaking-of-science/wp/2... Different anagen phase durations.
- harshaxnim 3y ago
  Still doesn’t answer - How does the follicle know that I cut my hair and needs to grow again to that length?
  - mkaic 3y ago
    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 3y ago
      So hairs are actually excretions, like sweat and shit.
      - bee_rider 3y ago
        What’s the opposite of a fun fact
        klyrs 3y ago
        Teeth

heresie-dabord 3y ago

> 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.

TravisCooper 3y ago

It's all designed. Top down, one mind. Designed. That's why it all works. Think about all the cells, and the thousands/millions of jobs they do, in perfect coordination just in your fingers or hands. It's all designed.

RoyalHenOil 3y ago
There is not some guy coordinating all our cells to grow and work in lockstep. It's actually just a few very simple algorithms (e.g., cells differentiation is triggered by strength of a signal, a la HOX genes) that have been very slowly refined over millions of generations of evolution. Just because the output of a system looks complicated does not mean that the input into a system is complicated.
- concernedParty 3y ago
  The most probable scenario for inorganic matter to be arranged and organised into a living, homeostatic self replicating machine, is for a number feature complete systems (including hardware and software) to appear all at the same time. If you don't start with all of them in place, the organism dies, and fails to benefit from both time and natural selection. Even in this model there are many chicken / egg scenarios. e.g. Every cell needs a membrane to survive, but how does a membrane benefit a cell if it has no ports built in to let waste out and food in? So the wall and the access control systems must appear simultaneously, or the cell dies and does not benefit from natural selection. Another one is DNA, it's information storage, but it's inert, it doesn't do anything except be acted upon by other systems, but DNA holds the information to create those systems. So how were the systems consistently replicated before information storage systems like DNA? You probably don't care about this because you seem to be answering something he didn't suggest... But he's not saying that every cell in our bodies is being actively managed by another being, he's saying that cells have been designed to self-coordinate. Anyway, just food for thought for other readers who may also have these questions, you're not alone, and it is worth investigating because the current paradigm is in crisis and it's not worth basing your life decisions on their ideas anymore.
  - 3y ago

Intralexical 3y ago

> 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. If they fly through the same air as airplanes, you also lose efficiency wherever you have wingtips (pressure below leaks above, basically), and the rear wings can get messed up by turbulence/vortices from the front wings if you're not careful.