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What Birds Know About Fractal Geometry 74

sciencehabit writes "In a new study, researchers find that a single number that describes the complexity of feather patterns on bird chests, a parameter called the fractal dimension, is linked to whether a bird has a strong immune system or is malnourished. When scientists restricted the food of red-legged partridges, the patterns on their chests had a lower fractal dimension than those sported by their well-fed colleagues. The food-restricted birds, on average, weighed 13% less than their well-fed colleagues and had weaker immune systems, which makes fractal dimension an easily recognizable sign of a potential mate's health and vitality, the researchers contend."
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What Birds Know About Fractal Geometry

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  • by CuteSteveJobs ( 1343851 ) on Thursday January 24, 2013 @04:16AM (#42678353)
    'Fractal dimension' seems like a cool buzzword which will make it easier to get research noticed, so call it what you will, but a the color of birds feathers except for blues are determined by their diet. Blue is determined structurally. The pattern is determined by proteins following genetically-laid out patterns, same as like stripes or spots on other animals. There is some logic that birds with good diets would have 'better' patterns as determined by their prospective mates.

    http://www.smithsonianmag.com/science-nature/Why-Are-Some-Feathers-Blue.html [smithsonianmag.com]
    http://www.birds.cornell.edu/AllAboutBirds/studying/feathers/color/document_view [cornell.edu]
    • by Anonymous Coward on Thursday January 24, 2013 @04:52AM (#42678475)

      You are absolutely correct, it just so happens that the patterns formed are also fractal in nature. All fractals are described statistically with fractal dimension, a relative measure of complexity, in order to differentiate between scaling properties in different fractal patterns. Really, all this research is saying is healthier birds have more complex patterned feathers, but with a mathematical definition of what that complexity is.

    • So it's the overall colour not the fractals? The title makes it sound as if the birds are doing some conscious calculation the way you might size up a new date as rich, poor, or in between.
      • Re: (Score:2, Interesting)

        What? The world has come to this? Instead of how intelligent, strong, or attractive we are, the primary factor is socio-economic status?

        Wow, I bet that realisation causes more than a few suicides.

        • by fuzzyfuzzyfungus ( 1223518 ) on Thursday January 24, 2013 @07:07AM (#42678831) Journal

          What? The world has come to this? Instead of how intelligent, strong, or attractive we are, the primary factor is socio-economic status?

          Wow, I bet that realisation causes more than a few suicides.

          At the level described in TFA(malnutrition leading to visible differences in development persisting into maturity) or similar(doesn't sound like they tested it; but parasite load and certain sorts of environmental pressures probably have the same effect) there really isn't a terribly strong separation of physical factors and socio-economic status(to the degree that birds have that). At the knife-edge-of-subsistence level, the fact that intelligence, strength, and attractiveness are paid for in calories and nutrient distributions really tightens the connection between personal virtues and economic status.

        • by lxs ( 131946 )

          Welcome to the human race. You'll find that like the majority of great apes, we are a social animal. Keeping track of your socioeconomic status is of prime importance for successfully navigating life within the tribe.
          Good luck on you exciting life as a human.
          ~the management

          PS. Don't fling poo, that's a chimp thing.

          • "Keeping track of your socioeconomic status is of prime importance for successfully navigating life within the tribe."

            Except there is one important statistic that contradicts this idea: people of "lower socioeconomic status" get married and breed much more often than the "upper crust".

      • by craigminah ( 1885846 ) on Thursday January 24, 2013 @07:05AM (#42678821)
        The title is misleading...the birds like the pattern and know nothing about fractals. Reminds me of the story of a mathematician's dog who "knew calculus" because of the way it waited for a ball to bounce off a wall. It didn't know calculus, it just learned what happens when a ball is tossed against a wall. To know calculus or fractal geometry would mean you'd do some form of calculations and be aware of the interrelationships of the variables within...neither the birds nor the dogs did any such thing.

        People at nightclubs simply like or dislike the way someone acts/looks to determine if they want to "mate" with them...no math there but a story will come out saying men and women at nightclubs perform complex trig to find mates.
        • by Viol8 ( 599362 ) on Thursday January 24, 2013 @07:31AM (#42678909) Homepage

          "a story will come out saying men and women at nightclubs perform complex trig to find mates."

          Hey , you've obviously never tried to look cool in front of some babes at a club while carrying a load of beers and having to carefully avoid all the drunks and druggies swaying about by calculating the optimal path across the dancefloor cross referenced in the time domain against the beat of the music!

          • In that case I was calculating the optimal curved path since I was inebriated...I must've inherited calculus from my parents then since I took calc after my clubbing days (I already had enough seals stored up).
          • It went fairly well until I pulled out the slide rule.

          • by museumpeace ( 735109 ) on Thursday January 24, 2013 @11:09AM (#42680199) Journal
            Did you see the movie "a beautiful mind" about John Nash...who took game theory as it existed in early '40s to a whole new level when he realized how it applied to the efforts his buddies at the bar were making to score with some girls who had shown up there? He was a genius then, and crazy, but his math was right.
        • The birds probably notice that the potential mate is malnourished and 13% underweight before they start calculating fractal dimensions.
        • The pictures of the bird are interesting, too. No explanation for them; probably because the larger image is a portion of the smaller image scaled up in size and reversed left to right. I guess viewers are to draw their own conclusions.

          • It's a detailed close up of the same bird to show the pattern. Did you think it was meant to be a different one?

        • no math there but a story will come out saying men and women at nightclubs perform complex trig to find mates.

          And if they decide they don't want to mate, they flip you the bird, and if they decide that they do, they flip you the mandelbird?

        • by nayrbn ( 2704751 )
          You have a very good point, and I get annoyed as well, but consider this. What does it mean that a dog learns how to bounce off the wall? The fact of the matter is that the dog has some procedure for determining its position that can also be figured out using calculus. That's the amazing thing. There was actually an Mathematical Monthly article called "Can Dogs Do Calculus." In it, the dog would seem to solve this optimization problem, though it turns out there is a simpler explanation for their behavior.
          • I think that article you mentioned was either in Slashdot or BigThink...probably Slashdot. Dogs aren't doing calculations, just as athletes aren't while playing sports, but they instinctively know what the results would be through past trial and error.
        • by cusco ( 717999 )
          No, the bird knows nothing of fractals, but it knows what it finds attractive in a prospective mate. Part of that attractiveness is the complexity of the feather pattern on the other bird's breast. That complexity can be measured by a human as a fractal dimension. Make sense now? No one is saying that a bird calculates an optimal fractal pattern to display its feathers, any more than a tree generates a fractal pattern before it grows a leaf.

          A dog can estimate the direction and speed of a ball as it b
    • by cupantae ( 1304123 ) <maroneill.gmail@com> on Thursday January 24, 2013 @08:30AM (#42679137)

      'Fractal dimension' seems like a cool buzzword which will make it easier to get research noticed

      Well, maybe it is, but you can't actually fault them for using it. The term "fractal dimension [wikipedia.org]" is as old as the study of fractals, and is taught in university mathematics courses. It is a useful concept, as you'll see if you read the wikipedia page. It's also consistent with the traditional geometric idea of dimension.

      I've only skimmed through the paper so far, but they've directly calculated the FD from its definition. The data looks pretty good. From what I've seen in the paper, I would say it's all legit.

      • Someone mod cupantae, there's nothing buzzy about "fractal dimension". Seriously, how did the parent get modded 5 insightful? Mod down please.
        • how did the parent get modded 5 insightful?

          Because so many mods think they know what a good comment looks like, even if they have no idea of its factual accuracy.

          Thanks, by the way.

      • by nayrbn ( 2704751 )
        In fact, my professor suggests that there's not much promise writing a thesis relating to fractal dimension! Not a new field indeed.
    • yeah, I'm pretty sure the feathers are just spread more because the bird is fatter.

    • It's common knowledge that the condition of a birds feathers is an indication of the overall health of the bird. One does not need to calculate a Fractal Dimension to see this. Somebody was jonesing for a research grant. Sad that a review board approved it.
  • by Anonymous Coward

    Birds know nothing about fractal geometry. It would have been extremely cool if they did.

  • by Anonymous Coward

    Is this related to the idea that the degree of golden proportion in the human face is a measure of beauty?

  • Now seriously! (Score:4, Interesting)

    by docilespelunker ( 1883198 ) on Thursday January 24, 2013 @04:56AM (#42678487)
    The notion of birds calculating the fractal dimension of a prospective mate's feathers seems about as farfetched as baseball fielders calculating the exact mathematical damped parabolic path of the ball to work out where to put their hand. It also indicates that if true, birds are much nerdier than my physicist friends and should in theory have less chance of getting a date. As such, this theory is debunked by birds not being extinct through lack of mating! I do buy the notion that birds could see the effect without doing the maths though.
    • But they might calculate the fractal dimension. Might see other correlated aspects of it.
      Just as they perform what computer scientist have lots of trouble replicating, that is the flight, the landing, the looking around.
      But all of this simply is a case of: "doesn't eat properly, looks like sh*t, doesn't get laid" phenomenon which occurs naturally in all species.

    • It's a gag. The authors of the paper, and of the article about the paper, are not seriously suggesting that the birds understand fractals. The fractal dimension is just a useful descriptor for pattern complexity.

  • by Required Snark ( 1702878 ) on Thursday January 24, 2013 @06:30AM (#42678719)
    Fractal dimension is not a set of buzzwords, but a useful concept in both mathematics and technology. http://en.wikipedia.org/wiki/Fractal [wikipedia.org]

    Fractals have many uses http://en.wikipedia.org/wiki/Fractal#Applications_in_technology [wikipedia.org] It is a perfectly reasonable hypothesis that birds recognize the fractal dimension of plumage in their own species. Conflating this with "being able to compute a fractal" is ignorant. Some birds are known to get information about magnetic fields through their visual channel. This does not mean they are solving Maxwell's equations.

    It is possible to extract fractal dimension information from images. Typing in "fractal dimension image detection" into Google Scholar results in over 25000 references. If academics have figured out how to do this then evolution may also embody these concepts.

    Posting on Slashdot is an opportunity to share knowledge and learn things. Unfortunately far to many people who post here show that they are ignorant and arrogant. I call them the Slashdot Pundits.

    Just because you know one thing does not mean that things you haven't heard of are wrong. With Google and the like, it's easy to fact check. On this topic so far all we have seen is woefully uninformed people criticizing academics and making fools of themselves. I would think that shear embarrassment would tend to eliminate this kind of drivel, but I guess if you are stupid enough to make such uninformed statements, you are also incapable of understanding how bad it makes you look.

    • by fuzzyfuzzyfungus ( 1223518 ) on Thursday January 24, 2013 @07:16AM (#42678865) Journal

      There is, arguably, a meaningful distinction between 'knowing' something(in the sense of being able to use that something in conscious cogitation) and 'knowing' something in the sense of 'exhibiting behavior that could not be accomplished without possessing some similarly capable mechanism; but not necessarily possessing any conscious knowledge, or even consciousness at all'.

      It's an open question(that the paper isn't really interested in attacking) whether birds 'know' anything about fractal dimension in the first sense, or what if anything they know at all in that sense; but there is a much stronger case to be made that they do exhibit behavior that could only be accomplished with access to the results of such a computation, even if the processing is a total black-box. Much the same is true of humans: you don't need to take physics to play catch(and, indeed, even those who have generally don't start using conscious calculation to catch falling objects); but our ability to catch objects is pretty hard to explain without positing that we have some mechanism that gives us access(and rather fast access, no less) to good approximations of answers to certain classes of physics problems.

    • by Anonymous Coward

      Wow, getting sheared and embarrassed at the same time sounds pretty harsh! Last I checked my wool coat was not thick enough yet so I'm safe for now.

  • Now, that should be worth an Ig Nobel [improbable.com], no?

  • Misleading title (Score:3, Informative)

    by henryteighth ( 2488844 ) on Thursday January 24, 2013 @08:40AM (#42679177)
    The title seems to be trying to suggest (to me at least, and based on the other comments here also to plenty of other readers) that birds can perceive fractal dimensions (FDs). However, if you read the journal article, it's all about a study of how the fractal dimension of the plumage correlates to different measures of the bird's health. They then also investigate some causative effects, by changing the bird's food intake and measuring the effect this has on FD. Nowhere in the article do they make any claim that birds can necessarily perceive or calculate a fractal dimension: the paper ends by saying "We therefore suggest that considering FD should shed new light onto the evolution and maintenance of complex animal patterns. " So they suggest (entirely reasonably IMHO) that it would be interesting to study that latter aspect, which is quite an important difference from what the Slashdot title is trying to imply.
  • by decora ( 1710862 ) on Thursday January 24, 2013 @08:44AM (#42679205) Journal

    if you are studying some awful disease, like smallpox, most people do not have a problem with purposely starving a mouse.

    if you are just doing it to measure fractals, a lot of people do have a problem with it... even meat eaters.

    "oh but we need basic research and that justifies it because it might save someone some day" -- yeah no it doesnt, unless you have some examples. because i can give you thousands and thousands of examples of where 'science' committed horrifying atrocities against human beings in the name of 'basic research' and used that same argument to justify it. thats the whole point - its not about 'save the animals', its about basic morality.

    • While I agree with you that this skirts the boundaries of research ethics (frankly the whole field of animal behaviour research is troubling):

      i can give you thousands and thousands of examples of where 'science' committed horrifying atrocities against human beings in the name of 'basic research' and used that same argument to justify it.

      Dozens, yes. (Mostly in secret, and without any a priori justification by the perpetrator.) Thousands?

    • Just to be clear, their protocol states that they observed a group of birds who were free to eat as much as they wanted and noted how much the different birds ate. This was a parallel study, where they just correlated food consumption to patterns with no intervention. Then for the intervention study, they fed the experimental group at the low end of that range.

  • It is truly the advancement of all humanity to study Fractal Patterns of bird feathers that have been starved; then to consider procreation in the same sentence.
  • The idea that something so complex could be automatic in a bird's perception based on visible traits is very interesting, but what intrigues me more is the possible correlation this could have to other species including humans. Immune malfunction, more specifically auto-immune disorders can be some of the hardest to diagnose (some can't actually be confirmed, only determined that you don't have anything else) and they have all sort of symptoms that resemble colds, allergies and other more easily diagnosed i
  • by jklovanc ( 1603149 ) on Thursday January 24, 2013 @02:20PM (#42681961)

    Birds know nothing about fractal geometry. One does not need to know the fractal geometry of a feather pattern to deem the pattern desirable.

    Another point is that they didn't prove the link between fractal dimension and desirability. It is quite possible that the prospective mate does not notice the change in plumage but looks at the overall health of the bird. Now if someone took identically healthy birds and modified some bird's plumage to change the FD and that changed the selection probability then that would be proof.

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