diff --git a/capra course.md b/capra course.md
index 5e1e0ba65..52a4b6532 100644
--- a/capra course.md	
+++ b/capra course.md	
@@ -63,5 +63,8 @@
 							- [[nitrogen fixation]]
 							- [[rapid motion]]
 							- [[respiration]] (!)
-					-
+					- [[evolution through symbiosis]]
+						- [[lynn margulis]] as well
+							- hypothesis: long term [[symbiosis]] involving [[bacteria]] and [[microorganisms]] as hosts led to complex life
+						-
 	- [[lecture 5]]
\ No newline at end of file