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No pollen grains were harmed in the writing of this dissertation.

The progression through grad school is measured in milestones; some are official (like qualifying exams), others less so, but no less important. This week, I passed such a milestone: I counted the very last pollen grain of my dissertation.

For those of you less familiar with the details of paleoecological proxies, let me explain. Pollen analysis, or palynology, is the study of ancient pollen grains in order to reconstruct past plant assemblages. Pollen, that copious evidence of plant sex that causes so much misery to allergy sufferers, doesn’t always end up fulfilling its procreative duty– oh, no! Much of it falls onto lakes (or bogs, etc.), settles to the bottom, and becomes incorporated into layers and layers of mud that accumulate through time, until one day, an enterprising graduate student comes along on a floating picnic table (unless you’re one of those winter coring people who stand on the ice) and pulls it all up in a long tube of mud: the core.

Pollen from the sunflower family. Beautiful, false-color micrographs like this are NOT what I actually see under the microscope. Image courtesy of Wikipedia Creative Commons.

We bring the core back to the lab, take many samples, do all kinds of nasty things to them with fun chemicals like acetic anhydride and hydrofluoric acid to remove sands, clays, humic acids, carbonates, and organic material, until all that’s left at the end is a mostly-pollen sludge. This pollen-rich residue then gets smeared on a slide for viewing with a microscope (400x), and painstakingly identified to the genus or family level (rarely species). Changes in the types and abundances of different types of pollen tell us about plant communities in the past– like how forests respond to climate change, for example. In my case, I use spores from a dung fungus to tell us about how plant communities changed following the extinction of ice-age herbivores.

But back to the pollen. A couple of days in the field translate into about a year in the lab, starting with the time it takes to put samples through the chemical digestions necessary to extract the pollen (as much as 40 hours for every 16 samples). Then, you count. And count. And count some more. For every sample through time, you need to make sure you count enough pollen grains to make sure you’re really getting a sense of the rare types (not all plants produce the same amount of pollen, which complicates things). I counted, on average, over 400 pollen and spores for each sample. “Counting” is an oversimplification– sometimes, the pollen are easy to identify (like grass). Other times, I’d spend quite a bit of time going through various keys and reference slides to determine a new or unknown type. Early on, there were times I realized I’d been mis-identifying a particular grain, and had to go back and re-check. Sometimes, my count sheet in Excel would crash. Other times, uncooperative sediments meant that I’d have to re-process an entire batch of samples in order to count them.

But now, I’m done! I figure I’ve counted more than 140,000 pollen grains for my thesis and dissertation. Figuring a pollen grain a minute, that’s 2300 hours in front of a microscope– more than a full year: that’s 1/30th of my entire life.

I’ve always said that all research involves tedium of some kind; you just have to find the tedium that bothers you the least. I generally enjoyed counting pollen, though I can’t say I’ll be sad if I never count another grain (in theory, I’ll have grad students, or even someday a computer, to do that). Pollen analysis wasn’t always tedium; I once caused an explosion in the fume hood by forgetting in a crucial moment that concentrated sulfuric acid is highly reactive with water (it really, really is). Another time, a house centipede crawled into my lab’s $60,000 Zeiss microscope and died, leaving a multi-legged spoke in my optics that had to be fixed by an out-of-state technician.

I am indebted to the many hundreds of hours of podcasts and audiobooks that got me through those 2300 hours, to the undergraduates that helped me in the field and with processing, and to coffee shop across the street for keeping me caffeinated through ten-hour counting binges.

And now, I get to analyze all that data.

P.S. The Donors Choose Science Bloggers for Students Challenge ends tomorrow (Saturday, October 22nd!). Through tomorrow, any contribution you make through my blog’s giving page will be doubled by the Donors Choose board (you’ll get a gift card to make a second donation to a project of your choice). We’re so close to funding the last three projects on my page, so if you’ve considered making a contribution, please don’t delay! And don’t forget, each  $5 contributed gets you an entry to win a set of custom science magnets in the theme of your choice (made by me)!

Categories: Grad School

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Jacquelyn Gill

13 replies

  1. Excellent read – currently doing my Dissertation and it humored me what you this is similar to me. Can I have a read of your dissertation? Please get back to me, thanks

    Dean

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    1. Hi I just came across this as its a particular interest of mine for several years. I would love to read your dissertation? Do get back to me!

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      1. Thanks for your interest! My dissertation is available through ILL from the University of Wisconsin Department of Geography, or you can read the articles themselves (and I’ve written blog posts when most of them have come out). My scientific papers are here:

        https://jacquelyngill.wordpress.com/publications/

        And you can read some of the blog posts on my research here:

        https://contemplativemammoth.wordpress.com/2012/01/26/a-paper-published-a-story-told-understanding-the-impacts-of-the-loss-of-ice-age-herbivores/

        and:

        https://contemplativemammoth.wordpress.com/2013/09/09/new-research-bison-dung-prairie-plants-and-mammoth-inferences/

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  2. I got here via twitter, in a rather contorted way. Nowadays I’m a plant pathologist, mainly molecular biology, but as a master student I did count loads of pollen grains, prepared whole fields worth of sediment samples and yes, acetolyzed and variously digested my share of pollen grains and sediments (without blowing up the lab, I must say proudly, even if we had a very basic set-up, all home made).
    I miss reading the slides, after the first months it is great to be able to “walk in the park” and just put all your attention to the “special cases”. And as I was doing a vertical transect at every new level I got something new, a new landscape, new plants to identify, it was fun. A bit less fun when my initial project, in collaboration with a group of archeologysts, had to be scrapped due to complete lack of pollen in the soil samples I got from them, I found that out only after spending 3 months preparing all the samples (the prof’s idea).

    I loved the job, but my supervisor advised me to change plan for the future, she told me that “there is no money in this field, and I have a colleague at the agricultural department that wants a botanist”, and off I went.
    Your post was a blast from the past, as no-one around me today has even seen a pollen grain up, close and personal, I eve had a half fight with a guy working on blood DNA testing that thought that pollen grain readings were woo, a sort of magical stuff without scientific foundations.

    Sometime I miss pollen…

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    1. I think there is still money in the field – at least, in the context of global change science. Though, there are the new automated pollen-counting computers that may well change the field– turning what took months into a relatively easy form of data generation. You’ve done a good job of articulating one of the things I love about paleoecology– the process of discovery.

      And, ouch! Soils often don’t preserve pollen well, and that must have been incredibly frustrating!

      I’ve talked to a few folks that think of palynology, and paleoecology in general, as a sort of mystical art. It’s really funny to me, because I’ve spent so much time doing the nuts and bolts work of it.

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      1. Well, that more than 14 years ago, in Italy, and for research in Italy there is very little money anyway. At that time it was almost impossible to continue in the field…
        I agree that recognizing pollen is almost an art, and take time to learn, but I still have a very good eye for small details and changes in morphology of whatever I look at, handy when doing other kinds of microscopy, as I do in plant pathology.

        I think automated readers will make life faster, but will require the “human touch” to recognize the strange objects, the exceptions and so on, and to figure out what to do with all the data. While not wasting months of a poor student life counting endless grass pollen grains….
        Again, “when I was young” we did not even have a digital camera attached to the microscope, and I had to annotate the coordinates of all the funny/unusual/too mangled grains I wanted to show to the supervisor the day after. This make me feel not just old, but ancient! 😉

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  3. Totally different field, identical emotion: when I completed my last tedium-task (collected the final of 15,000 models, not counting re-dos), I wrote thank-you letters to the tv shows that had kept me company, running in the background while I worked.

    When I finished my thesis, my local coffee shop framed the abstract and hung it over “my” chair where I’d worked while analyzing and writing pretty much every day for two years.

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