1.8 billion years in a jar

Photo (and chutney) by Stephen Heard.

Jim Croce would like to save time in a bottle, but I can save time in a jar. I mentioned recently that I make a mean mango chutney (with a connection, and I swear there was one, to public belief in vaccinations and global warming). Not long before that, I’d posted about the Plant Gastrodiversity Game. Putting the two ideas together made me think about the evolutionary history in every jar in my chutney. It’s easy to calculate such things these days, and I’m a world-class nerd, so of course I didn’t waste much time getting started. I’ll share my chutney recipe, and some things I learned from my analysis.

Mango Chutney:*

8 mangoes, peeled and chopped (or 1800 g frozen mango, which save a lot of time and probably has a lower carbon footprint)

 

Mangifera indica (Anacardiaceae)
4 tart apples (e.g. Granny Smith), chopped Malus domestica (Rosaceae)
2 c chopped onion Allium cepa (Amaryllidaceae)
6 cloves garlic, minced Allium sativum (Amaryllidaceae)
1 c chopped carrots Daucus carota (Apiaceae)
1 c raisins Vitis vinifera (Vitaceae)
1 medium habeñero pepper, minced Capsicum chinense (Solanaceae)
1 T ginger, minced Zingiber officianale (Zingiberaceae)
4 tsp black pepper Piper nigrum (Piperaceae)
½ tsp salt
1 ½ tsp cinnamon Cinnamomum cassia (Lauraceae)
½ tsp cloves Syzygium aromaticum (Myrtaceae)
2 tsp allspice Pimenta dioica (Myrtaceae)
2 tsp mustard seed Synapis alba (Brassicaceae)
1 T cumin Cuminum cyminum (Apiaceae)
1 tsp fenugreek Trigonella foenum-graecum (Fabaceae)
2 c white sugar Beta vulgaris (Amaranthaceae)**
2 c brown sugar Saccharum officinarum (Poaceae)
2 T lemon juice Citrus ×limon (Rutaceae)
4 c apple cider vinegar Malus domestica (Rosaceae)

Combine everything in a very large pot and simmer until (1) the house smells wonderful, and (2) it’s as thick as you want it. Getting to (1) happens very quickly, but be warned that getting to (2) can take several hours. Then package the result in canning jars (no need for a fork). The chutney is terrific on samosas, on scrambled eggs, or in cheese-and-chutney sandwiches – just as a start.

So how much evolutionary history is represented in each jar of chutney? Ah, here comes the nerdy part. I used the Phylomatic program in the Phylocom package to extract, from the Davies et al. (2004) consensus angiosperm phylogeny, the evolutionary tree represented by the 19 botanical ingredients in my chutney. Here it is:

chutney phylogeny with scale cropped

Adding up the lengths of all the branches (in millions of years) gives us our answer: 1,788 million years (or 1.8 billion) of evolutionary history in every jar of my mango chutney***. (You can do actual science with tools like this too).

1.8 billion years is a big number – but is it unusually big? I’m not quite nerdy enough to do this calculation for everything I cook, but I suspect the evolutionary history in my chutney is pretty respectable. Two things pack more evolutionary history into a jar: using more ingredients, and using ingredients derived from plants that are more distantly related. More technically: the set of ingredients is well dispersed across the plant phylogeny they’re sampled from (in contrast, a recipe combining tomatoes, eggplant, peppers, and potatoes, all in Solanaceae, would be phylogenetically clustered). My chutney rates highly on ingredient count (19), and not badly on phylogenetic dispersion (those 19 ingredients come from 15 families, with some fairly deep splits in the tree)****. So now my chutney tastes even better, because I know it took natural selection working in 19 different lineages nearly two billion years to get all those flavours right. It’s amazing what selection can do, given only time and variation.

Thinking about this leads me to suspect there’s a whole field of evolutionary gastronomy waiting to be explored. Human diets aren’t (I suspect) randomly assembled from available ingredients, and I have a set of hypotheses about this:

H1: Culinary ingredients are phylogenetically clustered, compared to all available plants. While we eat do plants from a lot of families, a few families seem likely to be overrepresented. Poaceae, Solanaceae, and Rosaceae spring to mind.

H2: Modern diets are more phylogenetically dispersed than ancient, or even historic, ones. Exploration, modern agriculture, and especially modern shipping, have made it possible for us to include plant families in our diet that simply wouldn’t have been available before (e.g., Musaceae (bananas) anywhere temperate; or Bromeliaceae (pineapple) in the Old World).

H3: Individual recipes tend to be phylogenetically overdispersed compared to the ingredients available in our cupboards or grocery stores. That is, I suspect we prefer dishes including contrasting flavours and textures (which we achieve by using distantly related ingredients) rather than more homogenous sets of related ingredients.

H4: Phylogenetic dispersion varies across cuisines. It will be lower in cuisines of temperate origin (accustomed to ingredient lists limited, pre-shipping, by the narrower set of plants that are cold-hardy), and higher in cuisines of tropical origin.

Each of these hypotheses is testable, although to my knowledge none has actually been tested. Of course, I might be the only person who thinks they’re interesting. If so, you probably stopped reading a while ago. If not, there might be several graduate theses lurking in this post.

So help yourself to the hypotheses. You’ll have to make your own chutney.

© Stephen Heard (sheard@unb.ca) January 14, 2016

Related posts:


*I’ve been making this for many years and no longer remember the source for this recipe, so I can’t acknowledge it here.

**I can’t be sure here, because sugar processors don’t tell you, but the majority of North American sugar is now from beet rather than cane. Brown sugar is often made from refined white beet sugar to which cane molasses is added (because beet molasses is apparently inedible). The things you learn…

***I’m excluding here the evolutionary history back from the common ancestor of all these ingredients (140 million years ago) to the origin of life on Earth (3.5 billion years ago). Including this “root branch” would boost my estimate to 5.1 billion years. But excluding the root branch is standard in this sort of analysis, and anyway, my jars are only so big. I should also acknowledge that this is a quick-and-dirty analysis: the Davies tree is conveniently available but is no longer our most recent estimate of angiosperm phylogeny, and there are a couple of polytomies I probably could have resolved with a bit of literature searching. I don’t think our final answer would change that much, though.

****Pesto, which combines basil and olives (angiosperms) with pine nuts (gymnosperm), packs an evolutionary punch out of proportion to its simplicity.

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14 thoughts on “1.8 billion years in a jar

  1. jeffollerton

    Great analysis and, yes, there are at least two of us who are interested in these kinds of questions of evolutionary (and biogeographic) gastronomy! But is it really meaningful to add up branch ages in that way to come up with a total of 1.8 billion years? Many of those species have been evolving over the same periods of time, so adding up their ages feels like double counting.

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    1. ScientistSeesSquirrel Post author

      Glad I’m not alone!

      The key to your question is that adding branch lengths captures years of independent evolutionary history. It would indeed be double-counting if I simply took 19 X 160 million years (160 million years being an estimate for the age of the angiosperms), or 19 X 3.5 billion years. But adding branch lengths is a pretty standard way of measuring phylogenetic diversity because if traits evolve independently along branches, then expected distinctiveness scales with total branch length. There’s actually a pretty big literature on this, going back to Dan Faith (and beyond). One good early reference is Faith 1992 Biological Conservation 61:1-10. Cheers!

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      1. jeffollerton

        Sure, I get that it captures phylogenetic diversity and distance between tips, but I don’t think you can (or should?) measure that in raw numbers of years, can you? Because very soon you’d encounter phylogenies where the combined phylogenetic age was greater than the age of the planet. Is that really meaningful?

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  2. Tony Diamond

    Steve: I enjoyed this post nearly as much as I enjoy the chutney! Dorothy made a fresh batch recently and we are consuming it greedily.

    Recently I borrowed a book from Thom Erdle called Enlightenment 2.0 by Joseph Heath. I found it extraordinarily good. In particular it clarified for me the difference between rational thinking and what he calls intuitive or heuristic thinking – the way our brains work most of the time. The key difference that struck me was that rational thinking requires *language* and that made me realise the cognitive connection between good writing and critical thinking. I have always felt were related “somehow” without quite realising how, or at least not as clearly as Heath describes. So, my point is that when we neglect teaching good writing (“we are teaching science, not English”), we are *neglecting teaching critical thinking *which we all agree is a big part of our jobs. I am wondering if you make this point in your scientific writing book? It now seems to me to be terribly important, now that I see the link made by developments in cognition science that Heath describes.

    I wonder if you know the book. It is among the most clearly written (on difficult topics) that I have read.

    Thanks for the blogs, they have become something I look for in my emails.

    Cheers

    Tony

    AW Diamond Research Professor, Wildlife Ecology Director, Atlantic Lab for Avian Research University of New Brunswick PO Box 4400 Fredericton NB Canada E3B 5A3

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  3. slimysculpin

    Your estimate would be substantially larger if vinegar was represented by Acetobacteraceae instead of apples. It wouldn’t be vinegar without the bacteria!

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  4. NK Simons (@Tritotanus)

    Thanks for this post, now I’m hungry 😉
    I was wondering about one detail: You wrote that “[your] chutney tastes even better, because […] it took natural selection working in 19 different lineages nearly two billion years to get all those flavours right.” But most of the flavours actually developed through selective breeding rather than natural selection. Take apples for example, each variety tastes completely different and I bet that you wouldn’t want any of the old varieties in your chutney 😉
    So, although the time it took humans to breed the varieties is extremely short in comparison to the millions of years of evolution, it might be interesting to also consider those years/generations. Maybe there is also potential for another hypothesis:
    H5: Cuisines differ in the amount of time invested in breeding the ingredients and the number of varieties available. Cuisines with a longer tradition and a lower number of plants originally cultivated have more selective breeding.
    I just realized that this would also add the whole field of anthropology, this topic is getting more and more interesting 🙂

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    1. ScientistSeesSquirrel Post author

      Selective breeding is a really good point – hadn’t thought of that at all. Nice job extending the frontiers of the new field! As you say, that would have a big effect for the apples and a few others – probably a minimal one for the cloves and cinnamon, and that might be another interesting topic right there. I would speculate that herbs and spices are used closer to the “natural” flavour than major ingredients are? Hmm…

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  6. Elizabeth Moon

    As I’m married to a chemistry nerd, who mentioned that only a biologist would fail to give the formula of the “salt” in your recipe to ensure its correct chemical identification, I suggest using sea salt next time. Sea salt analyzed for the mix of salts (sodium chloride, potassium chloride, whatever else is in that particular sea salt) so I can throw that at him, when he gets That Look on his face.

    Now the question of “age in a loaf of bread?” comes up. Limited number of ingredients, usually (though you can add all sorts of things to liven up the list.) I make several kinds of bread; the common loaf is wheat flour, yeast, cane sugar, and a fat (which can be bacon fat, butter, or vegetable shortening, depending on what’s in the house; it could also be lard, but I haven’t had lard in the fridge for years) and may include, for special occasions, cinnamon, more sugar, cocoa, and chopped nuts or raisins or both. Other spices, fruits, nuts, etc. have been used in bread too. I’ve made a dark bread with rye flour and wheat flour, and a bread with eggs and milk and butter. Adding animal products probably doesn’t increase the age of the composite, but surely the yeast does…or does the plasticity of the yeast genome reduce it? And what about sourdough breads, raised by combinations of CO2 releasing microbes?

    BTW, where I grew up and still live, much of the common granulated white sugar is cane sugar. There’s a town in Texas near Houston called Sugarland, which had a huge sugar processing plant; driving to Houston from South Texas, you had to go through it and smell the essential perfume, so to speak. Sugar cane was one of the first crops grown in the area where I grew up. I don’t think Sugarland has a sugar plant anymore. But the label on some brands of sugar still says cane sugar. We used to get “Mexican sugar” brought over from Mexico, a lovely not-quite-white sugar much more flavorful than regular American white sugar.

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    1. ScientistSeesSquirrel Post author

      As soon as you add yeast or animal fat, you’d add the evolutionary history back to their common ancestor – which is a lot. So your bread would dwarf my chutney for evolutionary history! (And you’re right, I didn’t quite know how to treat the salt.)

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