Every species on Earth has a story. My job as a paleontologist is to read and retell that story, so that we have a better understanding of how the modern world came to be. With Thanksgiving just a few days away here in the United States, my mind turned to the cranberry. When did they appear in the fossil record? Or in other words, how far back in time could a time traveler expect to find the ingredients for cranberry sauce?
Cranberry sauce is certainly a staple for many Thanksgiving dinners, with no shortage of styles. Some people really like the gelatinous cylinders that slide out of a can. My spouse advocates for her homemade recipe (included at the end of this post), with berries simmered gently alongside a mix of orange zest and just a trace of sugar. If you have any tooth enamel left after the stuff, it’s too sweet for her taste. I’m more of a gravy person, myself.
In any case, I was curious just how far back in time we can trace purported cranberry fossils. The cranberry you get in the store belongs to the genus Vaccinium, with Vaccinium (Oxycoccus) macrocarpon being the species most widely cultivated in North America. Vaccinium includes a bunch of tasty plants, such as blueberries, and the paleontological literature has many references to that genus. This turns out to be a bit problematic, though, particularly in the older literature. Leaves often look alike across distantly related species, and subsequent work has shown that many published identifications don’t hold up. Cranberries and kin provide an excellent example.
While researching this post, I got really excited when I found a paper dating the oldest Vaccinium to around 26.5 million years ago, which was used to estimate evolutionary rates for that part of the plant family tree. While tracking down the original citation, I found a brief mention of how that Vaccinium identification had been reconsidered. Sure enough, a paper by Wolfe and Schorn (PDF here) suggested that this oldest Vaccinium was more likely a type of barberry (genus Berberis). Barberry are used in cooking sometimes; they’re purportedly quite sour, so I imagine that in a pinch you could make some sort of barberry sauce to go with your meal. Just add lots of sugar. And, add a ton of caution when using published leaf identifications to infer evolutionary rates.
The next geologically oldest Vaccinium that I could find in the literature dated to the Miocene, around 15 million years ago (see citations here). We don’t know if they were blueberries or true cranberries or some sort of Mio-Plio-Berry, but it’s probably safe to say that close cranberry relatives existed. This also was just in time for some of the oldest presumed fossil turkeys! Our modern world was really starting to take shape then–recognizable horses, elephants, dogs, and such were all kicking around North America. I like to think that modern-tasting cranberries were there too, but we just don’t know for certain. The prehistory of modern Thanksgiving dinner ingredients is still woefully unclear!
Extra Bonus: Nichols Cranberry Sauce Recipe
By request, here is the homemade cranberry sauce recipe that we enjoy at Thanksgiving!
Put cranberries (1 or 2 bags) and a splash of orange juice and/or apple cider in a saucepan and start cooking. Zest an orange or two and add the zest, then supreme the orange and add the sections to the pot, squeezing the membranes to extract any remaining juice. Add a scant 1/3 c. sugar and wait until half the berries pop. Give it a good stir and taste. Add cider for a looser sauce, zest another orange if you want it orangey, and if you’re me, add sugar until you’ve split the difference between the tastes of the adults in the household. — Sarah Nichols, Ph.D.