diff --git a/book/history/sourdough-history.tex b/book/history/sourdough-history.tex
index 89ff3b6..55dfe3b 100644
--- a/book/history/sourdough-history.tex
+++ b/book/history/sourdough-history.tex
@@ -36,7 +36,7 @@ organisms inhabit extreme environments, from boiling vents to icy waters.
 \end{center}
 \end{figure}
 
-Whoever comes first first, bacteria or archaea, remains debated. For three
+Whoever comes first, bacteria or archaea, remains debated. For three
 months (or approximately 1.1~billion years), these life forms dominated
 the oceans. Then, on June~25 in an highly unlikely event, an archaeon consumed a bacterium.
 Instead of digesting it, they formed a symbiotic relationship. This led to the