Variation under domestication: pigeons

by Greg Mayer

Late summer is state- and county-fair time in much of the United States, and besides all sorts of odd foods (more on that below), these fairs afford a good opportunity to examine the phenomena of variation under domestication. These phenomena were of great interest to Darwin in helping him formulate his theory of descent with modification. He studied the amount and kinds of variation, the causes and inheritance of variation (less successfully), and, perhaps most important, the results of artificial selection. Besides his discussion in the the Origin, Darwin wrote a two volume monograph on the matter. That selection by breeders for slight variations could lead to large and permanent differences among domestic varieties provided Darwin with the vera causa he needed for natural selection.

A racing pigeon with "wild type" coloring at the Wisconsin State Fair, 9 August 2013.

A racing pigeon with “wild type” coloring at the Wisconsin State Fair, 9 August 2013.

On Friday I went to the Wisconsin State Fair, and headed straight for the small animal barn to see the pigeons. As we’ve noted before, Darwin’s own most extensive animal breeding experiments were with pigeons, and I like to see some of the many varieties up close and personal. The one above is very close to the wild form of Columba livia in color and pattern. The next few are also racing pigeons, but with varying colors and patterns.

[JAC note: As I recall, one of the readers for John Murray, the publisher of The Origin, said, when vetting the manuscript, that Darwin should jettison all the  dull stuff on natural selection and evolution and just leave in the interesting stuff about pigeons!]

Pink and white pigeon; notice the "wild type" bird behind it.

Pink and white pigeon; notice the “wild type” bird behind it.

Note that this bird retains part of the wild type pattern.

Note that this bird retains part of the wild type pattern.

So far we’ve seen birds bred for behavior, and for color and pattern. Some pigeon breeds are bred for aesthetic criteria, and these often have variant feather shapes and number. Tail feather number is a taxonomically important trait in birds, so changing tail feather number is in some senses a “big” change.

A fantail pigeon.

A fantail pigeon.

The next birds show feathering on the feet. This is also a trait developed in some chicken breeds.

Feathering on feet: heavy on bird in front, light on bird in back.

Feathering on feet: heavy on bird in front, light on bird in back.

The next bird has a crest of feathers on its neck and a ruffle of feathers on its forehead, as well as feathered feet.

Pigeon with crest on neck, ruffled forehead, and feathered feet.

Pigeon with crest on neck, ruffled forehead, and feathered feet.

The next pigeon I find the most interesting, because it has a distinctive head shape, quite different from that of wild pigeons; head and bill shape are of great adaptive and taxonomic significance in birds. It also has a neck crest and ruffled chest feathers; I think it’s a “turbit”.

A turbit, with modified head and beak shape.

A turbit, with modified head and beak shape.

Darwin was also struck by head shape variation in domestic pigeons, and illustrated this in his Variation of Plants and Animals Under Domestication:

Pigeons

Pigeons

So, Darwin learned from pigeons not only that selection was efficacious in changing the hereditary characters of pigeons, but also that the modifications possible extended to many characters (color, pattern, behavior, size, shape, feathers, skeleton), including those of great ecological and taxonomic importance. Thus, selection could account for adaptively and taxonomically important characters, and, given enough time, he argued, these could add up to large differences between groups.

[JAC addition: In the first edition of Darwin’s Origin, right in chapter 1 (“Variation under domestication”), Darwin establishes the crucial principle that, since animal and plant breeding are invariably successful, there must be ample genetic (“heritable”) variation in populations. Were this not the case, natural selection could not be efficacious and evolution of any sort couldn’t occur. Here’s a famous quote (my emphasis) from that chapter:

The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to a large extent some breeds of cattle and sheep. In order fully to realise what they have done, it is almost necessary to read several of the many treatises devoted to this subject, and to inspect the animals. Breeders habitually speak of an animal’s organisation as something quite plastic, which they can model almost as they please. If I had space I could quote numerous passages to this effect from highly competent authorities.

The breeder as sculptor! So one of the tests of Darwin’s theory was to see if one could take wild plants and animals and, using artificial selection, transform them in a desired direction. That would establish that those wild populations had genetic variation for things like size, color, behavior, body shape, and so on.  As Greg notes, all of these changes have been effected via selection on pigeons, descended from the rock dove.  He doesn’t mention behavior, but look up “roller pigeons.”

We now know that genetic variation is ubiquitous, removing one of the possible objections to the theory of evolution.  In Drosophila (the fruit flies I work on), there have been hundreds or even thousands of selection experiments on traits ranging from bristle number to behavior, and I’m aware of only three that did not change the population in the desired direction. Two of those three were done by me, involving selection on directional asymmetry (e.g., flies whose right eyes were bigger than the left, and vice versa.).  I haven’t yet published the second “failure.”]

Back to Greg:

And now for the food! The quintessential foodstuff of the Wisconsin State Fair is the cream puff (although there was some controversy this year about the source of the cream: from an Illinois-based dairy cooperative, but supposedly only from Wisconsin members of that cooperative, and actually prepared in Iowa). Regardless, they were delicious.

A Wisconsin State Fair cream puff.

A Wisconsin State Fair cream puff.

As regards this next advertised food, I don’t know what it is, and I didn’t find out!

Yikes!!

Yikes!!

47 Comments

  1. NewEnglandBob
    Posted August 12, 2013 at 4:52 am | Permalink

    What could be the reason for feathered feet? Is there some advantage or is this a bad trait that came along and will eventually be removed? (I know that last part can not possibly be answered.)

    • Dominic
      Posted August 12, 2013 at 5:08 am | Permalink

      Maybe it is an atavistic trait?

      • marcoli666
        Posted August 12, 2013 at 8:43 am | Permalink

        This has been of interest to me. Just mentioning an ‘out there’ idea, but the transitional birds like Microraptor and Archeopteryx, and other species, had flight feathers on their legs. I note the above pigeon leg feathers are also asymmetric, like flight feathers. I doubt that the pigeon breeders selected for this specific feather type. It is more likely that that feather type just appeared under selection for leg feathers. Your idea of an atavism seems possible to me.

        • teacupoftheapocalypse
          Posted August 12, 2013 at 1:16 pm | Permalink

          Many species of raptor also have feathered legs.

    • Alex Shuffell
      Posted August 12, 2013 at 5:13 am | Permalink

      Some Grouse species who live in very snowy places have feathered feet which function as a kind of snow shoe. Most of the examples of feathered bird feet are friends of breeders, the feathered feet are artificially selected for and require extra care. Many of the feathered dinosaur fossils have long feathers on their legs as well as arms, it looks like the leg and arm feathers evolved at the same time and most birds lost their feet feathers.

    • gbjames
      Posted August 12, 2013 at 5:28 am | Permalink

      The advantage is that some breeders like them.

    • Posted August 12, 2013 at 5:32 am | Permalink

      The reason the pigeons have them is because breeders like them– the “advantage” it provides is in the eye of the breeder. Some birds, such as ptarmigan and some owls, have varying amounts of feathering on the legs and feet, which seems to be adaptive to snow/cold. The development in domestic pigeons and chickens is beyond anything found in wild birds that I know of. Nicole Bouglouan has a very well-illustrated bird website, oiseaux-birds.com, that has a discussion of the functional morphology of bird feet which mentions feathering.

      GCM

      • John Taylor
        Posted August 12, 2013 at 9:02 am | Permalink

        Has anyone done a study of changes in domesticated pigeons since Darwin wrote about them? Have the various differences become more pronounced over time? Has anyone thought about doing multi-generational (human generations) breeding experiments to see how much change can happen over time? Would two separate species not emerge given enough time? Would there be any way to specifically select traits that would lead to the emergence of a new species?

  2. Dominic
    Posted August 12, 2013 at 5:12 am | Permalink

    Darwin, on preparing his pigeon skeletons – “the smell was so dreadful that it made me reach awfully”.

    See this letter to T.C.Eyton

    http://www.darwinproject.ac.uk/letter/entry-1784

    • Dominic
      Posted August 12, 2013 at 5:24 am | Permalink

      On the asymmetric drosophila eyes, I recall reading around 10 years ago of a rather unpleasant experiment in an ophthalmic journal, showing that the loss of an eye in a juvenile mammal results in an asymmetric development of the skull/face.

  3. Alex Shuffell
    Posted August 12, 2013 at 5:16 am | Permalink

    I’ve heard rumours of pork doughnuts being just regular doughnuts with shredded pork as sprinkles. The idea of savoury doughnuts has never occurred to me before.

    • Posted August 12, 2013 at 5:52 am | Permalink

      There are many ways donuts are combined with pork.

    • Gregory Kusnick
      Posted August 12, 2013 at 11:20 am | Permalink

      A few weeks ago at a farmer’s market I found a baker selling a variety of fruity scones. I chose one called simply “The Wedge” that looked like it had bits of black cherry and orange peel in it.

      Nope. On first bite it turned out to be a bacon-and-cheese scone, and definitely not my cup of tea.

      The following week the same baker was back with more bacon-and-cheese scones, but this time they were labeled correctly. So I guess I wasn’t the only one to be fooled.

  4. Hempenstein
    Posted August 12, 2013 at 5:22 am | Permalink

    Pigeons: Ever since I learned that dodos are related to pigeons, I’ve wondered how different they were at the molecular level. These pix suggest they might not have been all that different.

    Cream puffs: In Sweden, things like this are called semlor and marzipan (+ sometimes cardamom) is usually involved. Any spicing in these? Also, I note from the link that you can order them by the dozen locally and have them delivered – by ambulance! Presumably the ambulance then waits to transport you to the ER?

    • darrelle
      Posted August 12, 2013 at 5:54 am | Permalink

      I love cardamom. I use it as the signature hilight in my bread pudding recipe.

    • JBlilie
      Posted August 12, 2013 at 8:21 am | Permalink

      Normally (USian) cream puffs are not spiced in any way (except perhaps a little vanilla extract in the cream). Straight puff pastry filled with stiff cream whipped with a little sugar. Heaven! (If there were sucha place! :) )

    • Diana MacPherson
      Posted August 12, 2013 at 8:36 am | Permalink

      Mmmmm marzipan to boot!

      • teacupoftheapocalypse
        Posted August 12, 2013 at 1:22 pm | Permalink

        Marzipan? If there was ever proof of the existance of satan, marzipan is it! :)

        Vile stuff, together with its evil cousin, almond paste.

        • Diana MacPherson
          Posted August 12, 2013 at 1:35 pm | Permalink

          That’s rich coming from someone with a Marmite nym. Lol I tease of course.

          • teacupoftheapocalypse
            Posted August 12, 2013 at 2:09 pm | Permalink

            Just doing my bit to keep opinions polarised. :) Divide and play conkers!

  5. darrelle
    Posted August 12, 2013 at 5:58 am | Permalink

    Pigeons are often overlooked as being merely ordinary (at least I was once guilty of that), but they are pretty amazing birds with a long history of interaction with humans.

  6. Rara192
    Posted August 12, 2013 at 6:28 am | Permalink

    This isn’t evolution – they’re still just dogs!

    • Posted August 12, 2013 at 10:11 am | Permalink

      You mean, of course, that they — and we — are still fish.

      b&

  7. Diana MacPherson
    Posted August 12, 2013 at 6:41 am | Permalink

    Sub

  8. JBlilie
    Posted August 12, 2013 at 6:46 am | Permalink

    Cream puffs! Oh, yes!

    When I go, I eat nothing but fried cheese curds and cream puffs. Totally ridiculous; but I refuse to waste stomach capacity on anything less scrumptious! :)

  9. Vaal
    Posted August 12, 2013 at 7:22 am | Permalink

    That cream puff looks amazing.

    Had I been there I would have bravely, and altruistically stepped in and found out what “Pork Donuts” are. I’m in for savory and sweet.

    At our local CNE (Canadian National Exhibition) I had one of the most delicious breakfasts I’ve ever eaten: Stacked Red Velvet pancakes with layers of pulled BBQ pork, smothered in Jack Daniels infused syrup. I still dream of it.

    Now, about those pigeons. I’m thinking with a nice, sweet chili sauce…

    *snaps self out of it*

    Vaal

  10. Allautin@gmail.com
    Posted August 12, 2013 at 7:32 am | Permalink

    Carrier pigeons were “heroic birds” that carried messages over enemy lines in battle for thousands of years.

    During World War II, Project Pigeon (later Project Orcon, for “organic control”) was American behaviorist B.F. Skinner’s attempt to develop a pigeon-guided …
    (en.wikipedia.org/wiki/Project_Pigeon)

    Alas, these birds that carried messages behind enemy lines — and were trained to carry the explosive message inhering in a bomb — cannot convey the message that evolutionary processes are the case to creationists etc.

    It gets one to thinking that it is the creationists screed house a bird brain in their crania.

  11. Diana MacPherson
    Posted August 12, 2013 at 7:40 am | Permalink

    OMG those cream puffs look so good that just looking at them is making me hungrier! Now I want a total sugar lunch!

    People who breed cats and dogs should have to pass a course in genetics before they make some of the deleterious changes to animals based on their desire for a certain look.

    • Linda Grilli Calhoun
      Posted August 12, 2013 at 8:14 am | Permalink

      One of the things that pleases me greatly about the American Dairy Goat Association breed standards is that everything in the basic standard is directly related to structural strength, productivity, and longevity. Stuff like ears and coloring that are breed-specific are as far as we go for “fashion”.

      When the fashion part begins to affect the well-being of the animals, as in Pygmy goats, and several dog breeds, it’s time to ask what the point is. L

      • JBlilie
        Posted August 12, 2013 at 8:23 am | Permalink

        Dairy goats? Lucky you! (I am a goat cheese fiend.)

      • Diana MacPherson
        Posted August 12, 2013 at 8:37 am | Permalink

        Yes, I agree. It’s horrible what happens with breeding if you don’t have those rules about function.

      • Diane G.
        Posted August 12, 2013 at 11:08 am | Permalink

        I still find Lamanchas strange looking. Sweet, though. :)

        Boers are a good example of fairly recent selection in goats; but I hate their looks. I’m too used to the elegant dairy types.

        Sorry, I’m free-associating here. Your point stands!

        • Linda Grilli Calhoun
          Posted August 12, 2013 at 12:56 pm | Permalink

          When Boers were first introduced into this country, roughly twenty years ago, the ones that were here were really unsound – weak backs, bad pasterns, open shoulders. And, they were selling for astronomical amounts.

          I had a friend who was a semen processor at the time, who was spending a lot of time collecting Boer bucks, and I asked his opinion. He replied, “Most of those people have already taken a bath in ostriches.”

          The breed has come a long way since then. They are truly sound now.

          And, being a dairy breeder, I agree about meat type. But, if you’re a meat breeder, you’d probably feel just the opposite, seeing dairy breeds as “skinny”. L

          • Diane G.
            Posted August 12, 2013 at 1:37 pm | Permalink

            Interesting, Linda!

            For too many years, the newness/popularity of Boers meant that that’s where the excess kids for 4H’ers were coming from. Which meant the fair goat barns were always a huge disappointment. :D

            We’re in the process of losing our last pet goats to old age this summer; down to one (lonely!) 10-year-old wether. So sad.

            • Diana MacPherson
              Posted August 12, 2013 at 1:40 pm | Permalink

              Goats are awesome. I wish I could have one but I don’t have the facilities or time to make one happy. I have a goat calendar on my wall at work. That’s as close to goat ownership as I will get.

  12. Torbjörn Larsson, OM
    Posted August 12, 2013 at 10:24 am | Permalink

    Speaking of useful and/or selected pigeon traits, OB mention: their behavior illustrates the pigeonhole principle of mathematics.

  13. Diane G.
    Posted August 12, 2013 at 11:19 am | Permalink

    sub

  14. Posted August 12, 2013 at 11:29 am | Permalink

    Quite a few years ago I was working on Tenerife in the Canary Islands – studying canaries. The question was: Are the local canaries flying back and forth between Europe and the Canary Islands (migrating – and the answer is yes) or do the local populations stay local? At one point a local, knowing our interest in canaries, asked me whether I would like to see his collection of canaries which he bred. I said, “Sure,” and away we went. I expected canaries singing variations on canary songs. Instead he had featherless canaries, canaries with no feather on their legs, canaries with weird feather configurations – canary freaks in my untutored estimation – dozens of them. But, as it turned out, this is what quite a few Canary Island canary fanciers did. Darwin might have found these birds as interesting as pigeons. I found it creepy.

  15. W.Benson
    Posted August 12, 2013 at 12:31 pm | Permalink

    “In the first edition [of the Origin] . . . Darwin establishes the crucial principle that . . . there must be ample genetic variation in populations.”

    This is not entirely correct. Darwin proposed, as did two other important Darwinist’s Alfred R. Wallace and Ernst Haeckel, that ample genetic variation was produced anew each generation. Variation, in their view, resulted from the action of the environment, seen and unseen, on individuals. This is not to say that they were Lamarckians, for the variation induced could be directed or random. For the Darwinists, it did not direct the course of evolution. To the contrary, the course of evolutionary change depended on the direction of on-going natural selection acting on the ‘induced’ variability.

    The three (Darwin, Wallace, Haeckel) agreed that variation was typically small scale and arose simultaneously along innumerable different trait axes (not single variations away from a ‘type’ as Fleeming Jenkins argued). This (correct) view allowed for several co-associated traits to be selected at the same time in the same individual. Darwin’s academic coterie was impeded from suggesting unknown internal causes (even in the form of genes) without the risk of unleashing their demon of internal agents, vitalism.

    Environmental induction of heritable variation worked well as a heuristic model for variation in a theory that described how selection might make things evolve. This argument had the problem of requiring high ‘mutation’ rates that opponents could claim (also) drove Lamarckian type changes. This problem was fixed by Mendel. Environmental induction would also not explain how inbreeding, as occurs in small isolated populations, stalls evolution. Of course, Darwin was unaware of this fact. By the Darwin-Wallace-Haeckel model, populations of any size would have responded similarly to selection.

    Interesting insights on how Darwin and his ‘allies-in-natural-selection’ understood variation are presented in a 1932 paper by R. A. Fisher in the magazine Science Progress (Vol. 32, pages 273-287).

    • W.Benson
      Posted August 12, 2013 at 12:43 pm | Permalink

      Arrgh! (2)
      “Fleeming Jenkin”, not “Jenkins”.

    • Posted August 12, 2013 at 12:47 pm | Permalink

      I didn’t say the variation had to be pre-existing; just that it had to be there.

  16. W.Benson
    Posted August 12, 2013 at 12:34 pm | Permalink

    Arrgh! “Darwinists”,not “Darwinist’s”

  17. Posted August 12, 2013 at 1:18 pm | Permalink

    Jerry, If you get a chance, check out this post, on the Salt Lake Daily Issue:
    “Defending Darwinian Evolution – or – Why you never heard one damn word about evolution in school.”

    http://sldailyissue.com/2013/08/09/defending-darwinian-evolution/

    Also, an earlier work, recommending – and linking – to your book, on Amazon:
    Evolution – Putting a lie to rest

    http://sldailyissue.com/2011/05/19/evolution-putting-a-lie-to-rest/

  18. Mark Joseph
    Posted August 12, 2013 at 9:02 pm | Permalink

    Just wondering–did this post draw any condescending e-mails from creationists pointing out that “they’re still pigeons”?

  19. Jim Thomerson
    Posted August 13, 2013 at 6:36 am | Permalink

    Are the foot feathers on pigeons and chickens modified scales?


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