A photo book of biological marvels (and my own take on two of them)

I can’t brain today, which is lucky because there’s nothing substantive to write about—and I have other work to do. So enjoy these photographs from Robert Clark’s new photo book: Evolution: A Visual Record. I’ve selected a few photographs from a longer selection in the December 8 Washington Post. The notes at flush left are mine but are informed by the Post‘s captions. All photos are by Clark himself.

Below is a gynandromorph (half male, half female) of the Palawan Birdwing butterfly (Trogonoptera trojana): guess which half is male.  What probably happened here is that one sex chromosome in a male embryo was lost at the two-cell stage, so that the left half remained ZZ in sex-chromosome constitution, while the right half was ZO. (In birds and butterflies, unlike mammals and flies, males have two identical sex chromosomes, ZZ, and females have unlike sex chromosomes ZW. If you’re ZZ and lose a Z, you’re ZO, probably a female—and very probably sterile.) [Note added in proof: actually, this speculation isn’t correct; as reader Arnaud Martin pointed out in a comment on this site, Lepidopteran gynandromorphs are produced in a genetically different way. But the stuff about flies below is correct.]

This beautiful specimen is certainly sterile, with its body split right up the middle. Notice the longer antennae of the male as well as its shorter hindwing. It’s a direct way of comparing the traits that are sexually dimorphic, but in a single individual.

I sometimes found flies just like this, though the gynandromorphs were caused by a loss of the X chromosome in females, causing one half (or bits) of the body to be XX (female) and the other half to be XO (phenotypically male). Sometimes the loss of the X occurs later in development, so that only a portion of the body is male.

My undergraduate student Ryan Oyama and I used genetic tricks to make lots of these gynandromorphs (with the male parts identified by bearing a yellow body-color mutation), trying to find out where in the body the male cuticular hydrocarbons, which act as sex pheromones, were made. (Males and females have different pheromones.) I found that it was only when the abdomen was male did the gynandromorph produce male pheromones, so that area, I concluded, was where the hydrocarbons were made. (Each gynandromorph, carefully scored for where and how much was male vs female, was then assessed for its hydrocarbons using gas chromatography.) This location was later confirmed by others who directly found the hydrocarbon-producing cells—right under the surface of the abdomen.


Here’s the table from my PNAS paper with Ryan clearly showing that the abdomen must be male for the fly to have male pheromone, and female to have the female pheromone (female pheromone is 7, 11-HD or 7,11-heptacosadiene, male is 7-T, or 7-tricosene). The “H”, “T” and “A” in the first three columns refer, respectively, to the sex identification (F for female, M for male) of the gynandromorphs (“mosaics”) we produced. n is the sample size.


I was just reminded that Matthew had a post–a really good one–on this site about Lepidopteran gynandromorphs as well as gynandromorphs affecting behavior in Drosophila. The first comment on that post, by Arnaud Martin, corrects both Matthew and me in our speculations about the source of the gynandromorphism.

This is the moth that pollinates Darwin’s orchid (the orchid is Angraecum sesquipedale, the moth Xanthopan morgani).


The orchid, from Madagascar, was described by a French botanist in 1798, but came to be named “Darwin’s Orchid” because Darwin speculated that the flower, which had a long nectar spur—27–43 cm, or 10.6–16.9 in—must have been pollinated by a moth that could stick its very long proboscis all the way into the spur. (By so doing, the moth pollinated the orchid by pressing its head against the opening of the flower. Flowers produce nectar as a way to get their genes into the next generation through pollination.) Here’s the orchid (photo by B. J. Ramsay):


Darwin’s idea was ridiculed by some of his colleagues, but then the moth was discovered in 1903. Darwin, as usual, was right, though he didn’t live to see his vindication—at least about the moth.

Here’s how Wikipedia describes the pollination:

The fertilization of A. sesquipedale has been observed to proceed as follows. The moth approaches the flower to ascertain by scent whether or not it is the correct orchid species. Then the moth backs up over a foot and unrolls its proboscis, then flies forward, inserting it into a cleft in the rostellum which leads to the spur while gripping the labellum. After the moth has finished drinking the nectar, which usually takes about 6 seconds, it instinctively raises its head while removing its proboscis from the spur, and in doing so causes the viscidium to adhere to its proboscis usually about 4 to 9 mm (0.16 to 0.35 in) from its base.[22]Attached to the viscidium via the caudicle is the pollinia. Upon removing its proboscis from the flower, the pollinarium stalk will be straight and parallel with the moth’s proboscis. Then after leaving the orchid the caudicle will eventually dry out, causing its angle relative to the moth’s proboscis to change by 90° so that it is at the correct angle to attach to the stigma of the next orchid the moth visits. The moth then repeats this process at another A. sesquipedale orchid and simultaneously fertilizes it. Once the flower has been fertilized, it quickly stops producing its powerful scent.

I believe it was my friend Phil DeVries who first actually photographed the pollination event, which takes place at night (video at link).

You can buy a lovely print of the pollination event from Official Website Artist™ Kelly Houle.

I’ll add two more photos because Matthew, who called the Post piece to my attention, said they were his favorite pictures of the lot. I’ve used the Post‘s own captions here.


Not so long ago, it was a controversial theory, but now it’s widely accepted: Birds aren’t just dinosaur-like; they are in fact living dinosaurs. That’s true of everything from sparrows to eagles to Darwin’s finches — but it’s rarely more obvious than when looking at a southern cassowary (Casuarius casuarius), the flightless bird native to Australia and New Guinea that at 5 feet tall and over 100 pounds is one of the largest and heaviest birds on Earth. (Robert Clark/Courtesy of Phaidon)

And this is amazing, though there are much older hominin footprints (the Laetoli footprints, which date back 3.7 million years and were probably made by Australopithecus afarensis). Both show humans walking bipedally, and the A. afarensis footprints are direct confirmation of what was surmised only from anatomy.


“The combination of good sedimentary conditions and the fact that animals, including hominids, like to be near a source of water,” the great paleoanthropologist Richard Leakey said, helps explain why the remains of human ancestors — and many other creatures — are so often found near the shores of lakes. These beautiful human footprints, about 120,000 years old, were discovered south of Lake Natron, Tanzania. (Robert Clark/Courtesy of Phaidon)

Go see the other photos at the Post site.

Here’s Clark’s book, which is much cheaper at both Amazon and Target. It would make a great Christmas present for your evolution-loving friends or relatives.


h/t: Matthew Cobb


  1. jaxkayaker
    Posted December 11, 2016 at 11:57 am | Permalink

    Very interesting.

    Typo: “n is the same [sic] size”; should be “sample”?

    • jaxkayaker
      Posted December 11, 2016 at 12:13 pm | Permalink

      If anyone were going to buy me an Xmas present, I’d certainly ask for this book. I guess I’ll have to purchase it for myself instead.

      An interesting thing about gynandromorphs is they make plain that biological sex identity isn’t as simplistic and binary as some would want us to believe.

    • Posted December 11, 2016 at 12:41 pm | Permalink

      yes, sorry. Fixed.

  2. Simon Hayward
    Posted December 11, 2016 at 12:08 pm | Permalink

    Never mind the cassowary’s head – look at the feet! The play the jurassic park music in your head….

    • Simon Hayward
      Posted December 11, 2016 at 12:16 pm | Permalink

      Well that link doesn’t work well – sorry.


      If that’s no good – google is there to help!

      • Diane G.
        Posted December 12, 2016 at 8:19 pm | Permalink

        I clicked on the picture icon in your first post and it worked just fine. Yep, formidable feet! I understand they can deliver a fatal kick.

    • Derek Freyberg
      Posted December 11, 2016 at 1:37 pm | Permalink

      “Once there was a cassowary,
      on the plains of Timbuctoo.
      There he ate a missionary,
      head, and hands, and hymnbook too.”
      Ogden Nash, I think.

      • W.Benson
        Posted December 12, 2016 at 10:27 am | Permalink

        Somehow weirdly appropriate.

      • zytigon
        Posted December 14, 2016 at 12:53 am | Permalink

        Is that Timbuktu as a place holder name ?
        Wikipedia doesn’t list a Timbuktu on New Guinea or Australia where the Cassowary roams but there is a Timbuktu in Mali, and three in the U.S.A at Oregon, New Jersey, California.
        Is it possible that one went on vacation to Timbuktu though ? I doubt if there is much in the way of fruit & flowers for a Cassowary to eat at Timbuktu Mali as it looks desert like on google Earth

    • loren russell
      Posted December 11, 2016 at 4:03 pm | Permalink

      I can see where Jack Horner could go after Chickenosaurus. Not sure teeth would make it more fearsome than the beak, but hands, tail, and maybe a raptor second toe on the cassaowary?

  3. Gamall
    Posted December 11, 2016 at 12:13 pm | Permalink

    Fascinating stuff about the gynandromorphs — as a non-biologist, I didn’t know stuff like that was possible.

    • gravelinspector-Aidan
      Posted December 11, 2016 at 6:37 pm | Permalink

      Similar things happen to humans (for a variety of different reasons), which is part of the variety which is coming out to fuel the kerfuffles over sexuality and sexual behaviour. That’s just looking at physical circumstances – of course what goes on inside people’s heads is another random variable.

      • Posted December 12, 2016 at 6:43 pm | Permalink

        I’d add it makes me think of not only sexual aspects but the wide range of differences among humans and other animals, differences of many kinds, including temperamental and cognitive quirks, that could have a genetic piece.

  4. Mark Sturtevant
    Posted December 11, 2016 at 12:21 pm | Permalink

    This is totally fascinating.
    Some years ago, my wife had started to keep various species of orchids. We discovered that this is actually a huge business, and one can get all manner of orchids by mail order. Among these is ‘Darwins’ orchid’, on sale now here, and not at all expensive.

  5. Randall Schenck
    Posted December 11, 2016 at 12:38 pm | Permalink

    And how does religion explain the Gynandromorphy. Oh yes, he works in strange ways but always perfect.

    • Posted December 11, 2016 at 4:15 pm | Permalink

      Easy. G*d created the male insect, then created the female one from a part of it but forgot to separate them. Or, alternatively, a male and female insect “became one flesh” literally.

      • Randall Schenck
        Posted December 11, 2016 at 4:53 pm | Permalink

        Ah, but you make it sound so dirty….

        • gravelinspector-Aidan
          Posted December 11, 2016 at 6:48 pm | Permalink

          Is there a religion – any religion – that doesn’t take a prurient interest in how people (adherents and all others) chose which bits of skin to rub against other bits of skin belonging to any number (*) of other people?
          (*) Any non-negative integer of other people. Though I’m struggling to find a circumstance that could include a negative integer of other people. Non-integer people is a well known interest.

          • Randall Schenck
            Posted December 11, 2016 at 7:59 pm | Permalink

            I cannot think of any either regarding prurient interest, however with religion the inequality of this interest between the sexes is a major dysfunction as well. But on the main point it really does not look good for the omnipotent one to be having so many screw ups.

            • gravelinspector-Aidan
              Posted December 11, 2016 at 8:54 pm | Permalink

              The economic disadvantage of keeping half of the population outside economic activity will eventually do for the discrimination-based religions, but it’s going to take a long time to economically destroy those who depend on domestic slavery. I note that the two systems co-existed for nearly a century in America between the Constitution and the Emancipation, and it eventually took a war and a 150yr of effort to get to … well, Trump and the perceived need for “Black Lives Matter.”
              I don’t sound too optimistic, do I?

              • Randall Schenck
                Posted December 11, 2016 at 9:13 pm | Permalink

                No, you do not, but with good reason. Trump is a disgrace to the equality of sex and race and more. The only optimistic view is that the next four years run by quickly and the damage is not too great.

  6. rickflick
    Posted December 11, 2016 at 1:54 pm | Permalink

    Amazing images.

    I wonder how the Darwin’s Orchid’s nectar spur evolved as a function of time, and whether it is still changing? It might, I suppose, been subject to lengthening and then reached an equilibrium of some kind. Perhaps the moth’s weight or center of gravity became too much to continue the race.

    • gravelinspector-Aidan
      Posted December 11, 2016 at 7:10 pm | Permalink

      Perhaps the moth’s weight or center of gravity became too much to continue the race.

      Hmmm, since moths normally (TTBOMK) feed while resting on the flower (or some other structure), gross weight seems unlikely to be a significant contributor. Moths only extend their proboscis when feeding – they coil it compactly when in motion of flight – centre of gravity doesn’t look that much of an issue either.
      Looking at this picture of the orchid, it looks as if the flower part which the proboscis penetrates is a long, thin-walled tool. The mechanics of such are well known, and the stiffness of the tube is strongly constrained by the diameter of the tube and the wall-thickness of the tube and the stiffness-to-weight-per-unit-length ratio. I’d look at that as the main control on the system – but I note that you can seriously bolster the strength of such a tube by linking it to a “spar” with some larger diameter shape, decoupling the hydrodynamics of the pollenation structure from the mechanical apparatus. Are the tubes air-filled, or fluid-filled? (Actually, making the tube walls of layers of closed-end tubes would also bolster the stiffness a lot without greatly increasing the weight.)

      • gravelinspector-Aidan
        Posted December 11, 2016 at 7:11 pm | Permalink

        long, thin-walled tool.

        “tube” not “tool”.

      • rickflick
        Posted December 11, 2016 at 10:14 pm | Permalink

        It occurs to me the proboscis would have to be completely unfurled to get the business end into the mouth of the nectar tube. Then it would have to fly the damned thing in. This could put a bit of off to the moths kilter.

        • gravelinspector-Aidan
          Posted December 12, 2016 at 7:26 pm | Permalink

          Unfurled, yes – but that doesn’t mean that it’s rigid. Un-coil it, then lower the end into the trumpet of the flower ; adjust the turgor of the proboscis to navigate it into the trumpet, but with a significant part of the load of the proboscis supported by the wall of the trumpet.
          Ever tried getting a bolus of rags down the inside of a loose pipe to clean it, using a chimney-sweep’s push rod?

          • rickflick
            Posted December 12, 2016 at 7:58 pm | Permalink

            Makes sense.

      • Diane G.
        Posted December 12, 2016 at 8:29 pm | Permalink

        While the vid at Jerry’s link stops just before the moth appears, you can see the encounter starting at about 3 minutes into this link:


        The moth appears to be flying throughout at least the intromittent phase of the pollination.

        • rickflick
          Posted December 12, 2016 at 8:44 pm | Permalink

          Thanks. I thought I had seen that feeding behavior somewhere. It seems to bend the proboscis at the middle to help find the good stuff. Looks a bit like a fishing pole and line.

        • gravelinspector-Aidan
          Posted December 12, 2016 at 9:04 pm | Permalink

          I see that. The proboscis is unfurled, but not uniformly. At about half length there is a bend in the proboscis – the proximal section is canted upwards at around 20 degrees to the horizontal and the distal section down at about 45 degrees. The tip of the proboscis is then laid onto the mouth of the flower and the whole lot goes thoroughly Freudian. That deviation from horizontality and the bend will bring the centre of gravity of the proboscis in by quite a bit. If the full length is about 30cm, then that’ll bring the CoG in by something like 3-4cm. More if the proboscis is tapered.
          Got a tent with a glass-fibre poles? Try threading one of the poles into the flysheet sleeve while holding only the other end of the pole.
          Ah, some classic Blackadder : “Cold is God’s way of telling us to burn more Catholics.”

  7. merilee
    Posted December 11, 2016 at 4:19 pm | Permalink


    • Diane G.
      Posted December 12, 2016 at 8:38 pm | Permalink


  8. Posted December 11, 2016 at 4:35 pm | Permalink

    The discussion of gynandromorphs is really interesting. Does this condition reduce the viability of specimens that exhibit it? Also, are they always sterile? I hope your student realised how lucky he was to get a publication like that, while still an undergraduate.

  9. Merilee
    Posted December 11, 2016 at 6:03 pm | Permalink


  10. Patrick Clark
    Posted December 11, 2016 at 11:35 pm | Permalink

    It is an excellent book, with photos from around the world gleaned from 15 years of work with the National Geographic. His instagram feed is also worth a follow.

    full disclosure: he is my brother.

    • Diane G.
      Posted December 12, 2016 at 8:30 pm | Permalink

      What an exciting life he’s led!

  11. A. Diluca
    Posted December 12, 2016 at 10:12 am | Permalink

    Love it. But as usual, someone always find something negative to say. Here is me: the proboscis in the cover photo should have been placed away from the T of evolution. It makes it look like a cross.

    • Diane G.
      Posted December 12, 2016 at 8:35 pm | Permalink

      Oh, I think that’s quite a stretch! (So to speak. 😉 )

      I think the artist was just going for a sort of “rule of thirds” at that part of the cover to make it more aesthetically pleasing.

      I like the design; shows much more of the moth than had they tried to keep the entire proboscis below the title and also emphasizes the crazy length of the latter.

  12. Posted December 12, 2016 at 12:46 pm | Permalink

    _Evolution: A Visual Record_ is also available through Chapters, and in some of their stories (here at least).

  13. Posted December 12, 2016 at 12:47 pm | Permalink

    Where do the names for the sex chromosomes come from? Is there anything in common between the “X” of a human and the “X” of the relevant flies?

  14. W.Benson
    Posted December 13, 2016 at 11:29 am | Permalink

    Concerning sexual dimorphism of the gynandromorphic birdwing butterfly:

    The sexual difference in wing shape is probably related to different reproductive adaptations. Females usually mate just once or twice and spend much of their lives inside the forest seeking out places to lay eggs. Host-plant search and egg-laying requires negotiating thick vegetation and may be facilitated by broader wings giving maneuverability and slower wing beat. Males, on the other hand, tend to inhabit sunny, open places where speed is important in searching for receptive females and possibly in defending mating territories from rival males.

    The bright coloration of the male birdwing may be related to male-male recognition (driving away or spacing-out rivals) and as warning coloration (the caterpillars of birdwing butterflies feed on a toxic host-plant – Aristolochia – making the butterflies themselves distasteful to birds). It seems unlikely that female preference for brightly colored males has selected the color difference: courtship is initiated by the male and in butterflies female recognition of males seems to be mainly, if not exclusively, mediated by pheromones and male movements. The documented cases of female butterflies accepting males on the basis of color mostly concerns species with UV-reflective patches, not general coloration or color-pattern organization.

    The antenna on the female (right) side of the gynandromorph has a broken tip and is not naturally shorter.

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