In 2002, the Moore Foundation made a long-term commitment of $300M to the California Institute of Technology “to support the institution to advance its position at the forefront of higher education, technological development, and scientific research.”
The foundation’s commitment to Caltech, one of the most sizable donations to an institution of higher learning, has enabled breakthrough research that is advancing science in a number of different fields. In this installment of Beyond the Lab, we learn about John Eiler, Ph.D., who is the Robert P. Sharp Professor of geology and geochemistry at Caltech. Eiler is also a grantee through the foundation's Marine Microbiology Initiative.
What gets you going every day (besides coffee) and how do you stay motivated?
The earth sciences have evolved to be a clearinghouse for every area of the natural sciences that other disciplines used to study. Almost anything that happens in the natural world that’s observable at human scales used to be studied in physics, chemistry, astronomy, or biology, but is now geophysics or geochemistry, etc. I sit in an environment where almost every area of the natural sciences is studied, and I end up working in all of them, which I enjoy immensely.
What inspired you to become a scientist?
I went to college to be an anthropology major at Beloit College, which had a very good archeology museum—the best in the country at an undergraduate institution. I got a job there painting numbers on flakes of stone, and I thought that’s what I’d stick with, but to satisfy a science requirement I took a geology class. Because I had basic skills at fishing and canoeing growing up in the Midwest, the geology department hired me as a porter for field excursions, which involved carrying the department chair’s canoe and setting up tents. After a couple of trips, it seemed like geology would be a better match with my personality—the earth sciences are a very collegial, easygoing environment.
Watching geologists work on mapping crystalline rocks of the oldest part of the earth’s continents, which is called hard rock geology or petrology, really interested me and led to my pursuing a Ph.D. at the University of Wisconsin studying the history and petrology of ancient mountain belts, rocks that are billions of years old. Ironically, I spend a lot of time in a basement now.
The research group I worked with at Wisconsin applied an unusual kind of chemistry that involves studying the distribution of naturally occurring isotopes in natural materials, like oxygen. If you look at the periodic table, oxygen has a mass of 16—well, most of it does, but some small fraction of it has a mass of 18. These isotopes are hidden behind the periodic table (this is what “isotope” means: the same place in the periodic table). Same for hydrogen, carbon and nitrogen.
There’s a field of geochemistry that examines subtle variations in concentrations of these rare isotopes, like when carbon is fixed into plants there is a discrimination for 12C and against 13C. Once you recognize these effects, you can use them to create tools for studying all kinds of geological, biological and chemical processes.
As a student, I developed tools to study how heating or cooling minerals that are next to each other in a rock cause isotopes to migrate from one mineral to another. This can lead to a thermometer—a way to study past temperatures of geological materials based on the separation of isotopes in minerals: At very high temperatures, isotopes are randomly distributed in molecules. At low temperatures, they wish to distribute themselves between minerals unevenly – more in one mineral and less in another. This effect is temperature dependent. Also, if you recognize the isotopes are sluggish in the way they move through mineral structures, maybe they want to move but they can’t do it fast enough so they get stranded. This creates a gradient or profile that records how hot a rock got and how long it spent at each temperature.
My current research group asks similar questions about temperature variations during past climate change or tectonic uplifts using another effect: the tendency of rare isotopes to ‘stick’ to each other, sharing chemical bonds in molecular and mineral structures. We can use this technique to study the difference between carbon dioxide that enters the atmosphere when you exhale vs. that emitted in the exhaust of a car driving by. We even used this sort of isotope chemistry to determine the body temperature of dinosaurs. All kinds of information can emerge from this simple tool. Our ultimate goal is to apply this technology to the organic molecules of life in the environment, which could be used in forensics, personalized medicine, pollution, biological ecosystems and life in space.
How do your colleagues help you achieve your goals?
When I came to Caltech as a postdoc, I worked with Sam Epstein, a leader in the field of stable isotope chemistry, which was invented in the 1940s. His genius was to figure out that there are places in our understanding of geochemistry and cosmochemistry where no one has been, and to go there. He made the first isotope thermometers to measure the temperature of the ocean in the geological past, and could be considered the academic parent, grandparent, or great-grandparent of nearly everyone in this field.
Ed Stolper, who was another one of my postdoc advisors, suggested I take a leap from what I had studied before and pursue isotopes in igneous rocks, which form when magmas generated in the earth’s interior rise into the crust and surface, and quench to minerals and glass. The chemistry of these rocks provides indirect samples of the chemical variations of the earth’s mantle and deep crust – parts of the earth that are otherwise inaccessible and hard to study. Inspired, I applied my knowledge of analytic techniques to this question and many others, including hydrogen in the environment.
Once I became a professor at Caltech, and had gotten used to the idea that I could just pivot between subjects, this became my model. I could figure out ways to go into subjects that are new to me but are clearly important, with obvious questions on the table, and find a way to say something new and helpful by bringing to bear new technologies and basic understanding of the chemistry of isotopes that hadn’t occurred to people in the field.
The academic culture here at Caltech is so different from any other place I had seen before my postdoc, and I will say this is true to this day. I visit academic, private and government institutions all over the world, and there is nowhere that is like this place. It’s very dense in terms of the packing together of people who are talented in science, technology, engineering and math, but the Venn diagram of the institution has lots of just-barely overlapping circles. It means you learn from all of these talented people, and you kind of understand what they are talking about, yet each person has their own space where they can explore and grow.
To learn more about John’s research, visit his
website.
Message sent
Thank you for sharing.