Sonia Zarrillo and Cacao’s 5,300-Year-Old Clues
Men and Women of Cacao · History of Cacao
An ancient vessel can survive long after the food it held has disappeared. In a warm, wet landscape, seeds and other plant remains may decay. The question becomes whether something smaller has stayed behind: a starch grain, an absorbed chemical trace or a fragment of DNA.
At Santa Ana–La Florida in southeastern Ecuador, those small traces became part of a major revision to cacao's documented past.
A site in the upper Amazon
The archaeological site lies on the eastern side of the Andes, in the upper Amazon region. The people associated with its early occupation are known through the Mayo-Chinchipe archaeological tradition. Excavations and the work of Ecuadorian and international researchers provided the context for studying the site's vessels. [1, 2]
Geographic guide to places in this story. Modern outlines and approximate locations provide orientation; no historical route is implied. Base geography: Natural Earth (public domain).
The story therefore begins with the people who used the plant, made the pottery and lived in that landscape. Modern researchers were investigating traces of their activities thousands of years later.
Three clues, one stronger case
The 2018 study, led by Sonia Zarrillo with a large international team, combined cacao starch grains, absorbed theobromine residues and ancient DNA. Together, the methods supported identification of cacao use dating to approximately 5,300 years ago. [1, 2]
Illustrated guide: Three complementary clues in ancient vessels: starch, theobromine residues and ancient DNA. Sources and context below.
Each line of evidence had a different role. Microscopic plant structures, chemistry and genetic sequences could be evaluated alongside one another and alongside the archaeological context. The interest lay in their convergence.
A result made by many people
Zarrillo was the paper's lead author. The collaboration included archaeologist Francisco Valdez, Michael Blake and researchers working across archaeology, chemistry, genetics and agricultural science. Excavation, sample preparation, laboratory methods and interpretation all contributed to the result. [1, 2]
A profile of one researcher can make the turning point easier to follow, provided the team and the ancient community remain in view.
What the discovery changed
The evidence placed cacao use in the upper Amazon substantially earlier than the then-familiar archaeological evidence from Mesoamerica. It gave researchers a stronger basis for investigating cacao's early South American history. [1, 2]
The finding did not identify the first person to use cacao, the exact first preparation or a single proven route north. Those are different questions. The dated evidence establishes a chapter in an earlier and larger story, with more of that story still to be investigated.
Why a method can change a history
Zarrillo's contribution shows how a new combination of methods can make an old object speak more clearly. A vessel that appears empty can still contain evidence capable of changing a timeline.
That is a fitting place to leave this first season of Men and Women of Cacao. Consequential decisions do not all happen in palaces, farms or factories. Sometimes they happen when researchers decide to ask a familiar question in several independent ways—and discover that the past has left more clues than anyone could see.
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