As a visiting PhD student and now a postdoc in the Summons Lab, Sistiaga, uses techniques in organic geochemistry and paleolithic archaeology to investigate the role of diet and the gut microbiome in human evolution. Sistiaga analyzed fecal samples in sediment from El Salt, a Neanderthal site in Spain, for biomarkers of metabolized animal and plant lipids, and found evidence for substantial plant ingestion, which represents the oldest evidence of hominin omnivory and human fecal matter (50,000 years) found thus far. This implied that Neanderthals from this area, though having a meat-based diet, complemented their nutrition with plants. Previously, scientists had been looking at isotopes of carbon and nitrogen in bone collagen to evaluate Neanderthal diets, but this technique only shows the protein portion of their diet and they aren’t well preserved in this region. Her previous work on wild chimpanzees and gorillas helped her to better understand the effects of this bacterial conversion on the ingestion of cholesterol rich food.
Each summer, she also performs paleoenvironmental reconstruction in Tanzania, where some of the first humans were thought to have evolved. Samples from the site date back 2 million years, and by studying n-alkanes from the plants, Sistiaga can better understand the ecological context of evolutionary and dietary pressures humans were under at the time.
Another of Sistiaga’s fieldwork projects aims to trace the evolution of the human gut microbiome from ancient humans to the present. As research is being done on the microbiome, scientists are beginning to appreciate its importance in human biology, but little is understood about its coevolution in humans, since DNA and proteins degrade quickly in the fossil record. Since lipids are more stable on longer timescales, Sistiaga is analyzing samples from mummies to present-day populations looking for connections. She’s focusing on non-westernized cultures since less is known about them, analyzing fecal samples and genome sequences from people in more than 50 countries. Sistiaga is isolating and examining lipid biomarkers, which she can then match to specific gut bacteria that are responsible for their production, building a database. She’s working with the MIT Department of Biological Engineering’s Eric Alm lab and the Broad Institute to help preserve the samples, which could one day contribute to medical therapies related to the microbiome.
Name: Ainara Sistiaga Hometown: Lanzarote, Canary Islands, Spain Area of Study: Geochemistry and Archaeology Faculty Sponsor: Roger Summons
Education: Sistiaga holds Bachelor and Masters degrees in History from the Universidad of La Laguna in Tenerife, in the Canary Islands as well as a Masters degree in Organic Chemistry from the Université de Rennes 1, France.
Path to MIT: Sistiaga first came to EAPS as a postdoc under the NASA Astrobiology Origins of Life grant. Now she has her own funding with the European Commission which is allowing her to pursue her research, spending two years at MIT followed by a third year at the University of Copenhagen in Denmark.
Outside Interests: Sastiaga says she likes to read historic fiction. She is also passionate about past and modern human nutrition so, not surprisingly, really enjoys cooking. She says, "Swimming is my way to escape stress and daily tasks, better if it is in the sea but an hour in the pool usually is enough to completely change my mood."
EAPS Postdoctoral Program
The Department of Earth, Atmospheric and Planetary Sciences at MIT is committed to providing excellent opportunities for postdoctoral study with faculty who are widely recognized for their contributions to their fields. We offer broad exposure to all areas of the geophysical and planetary sciences, leading to work that is both rigorous and rewarding.
Postdocs are appointed after recommendation by a faculty sponsor, and the Department hosts 35-65 postdocs with active appointments in any given year. Candidates interested in postdoctoral study at EAPS are encouraged to contact the appropriate faculty member directly.