It’s January 3, and my third full day in the field here in Chilga, Ethiopia. I’m in the last 6 months of my PhD in paleontology at Penn State and the Smithsonian, and this trip is a vacation from my thesis work and hopefully will set me up for a post-doc with field work in East Africa. I study the fossil record of the interactions between plants and the insects that eat them. I’m interested in how plants and insects co-evolve — it’s an arms race — plants evolve better defenses, insects adapt to those defenses, plants continue to evolve, etc. I’m also interested in how insect feeding on plants changes during environmental perturbations, particularly climate change.
Insect feeding is preserved on fossil leaves. For example, if an insect chewed a hole in the leaf while the leaf was alive and on the tree, the leaf will thicken the tissue around the hole, forming a kind of scab. This thickened tissue is visible as a dark rim on the fossil leaf, and so I can count it as insect damage. To look at how insect damage changes through time, I dig up fossil leaves from rocks of different ages — my goal is to get at least 800 leaves from each age. For every leaf I look at, I record what species it is and what types of damage it has on it. Then I can use statistical analyses to find variations through time.
For my PhD, I’ve been looking at how global warming affected plants and insects 55 million years ago in the Bighorn Basin. My long-term goal is to look at changes in insect damage across East Africa over the last 65 million years, a time interval that includes the opening of the rift valley, a decrease in rainfall, and the expansion of open environments. And also the evolution of hominids. Here in Ethiopia, I will look at leaves that are 27 to 28 million years ago, when there was still rainforest in what is now arid grassland. So far, I’ve counted about 500 leaves — they are thick and tough and do not have a lot of insect feeding on them.
This is my third trip to Africa, but my first to Ethiopia. It is an amazing, new experience. When I do field work in Wyoming, I sit alone with a field assistant on a hill in the middle of the desert. Here, I have several Ethiopian assistants who dig my quarries for me, and bring me fossils to examine. I get to watch children herd goats, cattle, and oxen, and they come and stare at me. First there’s just a couple kids, but then I’ll get wrapped up in my work and I look up and there are a dozen children. They must wonder what this crazy white person is doing in the middle of the countryside looking at rocks. (Actually, people in Wyoming wonder that, as do my friends who are not geologists or paleontologists!) Today one of the children brought us tella, which is the native “beer” — it’s made of fermented tef, the grain they use to make bread here, and every family makes their own. Tella is definitely an acquired taste — there’s a hint of tobacco flavor and it’s not strained, so there are grain particles in it. I almost spit out the first sip I had, but now, after a long, hard day in the field, it tastes awfully good! Tomorrow, I get to stay in camp and work on the fossils I’ve collected already — they’re starting to build up in my tent. I might also attempt to wash my hair using the camp shower. I’m looking forward to seeing the stars again tonight. When we’re not running our generator and camp lights, we’re so far from electricity that the night sky is better than a planetarium. Having grown up in Chicago, where you can see about 20 stars on a clear night, I am always enthralled by a sky full of stars. Bye for now, or, as they say in Amharic, “deuna hunu.”