History professor David Cannadine’s unorthodox focus on cooperation as an agent of human history (Campus Notebook, April 3) dovetails with the observations of David Toomey in his recent book Weird Life: The Search for Life that Is Very, Very Different from Our Own. Toomey cites a particularly significant symbiosis of microbial evolution that ultimately developed into a codependency so complete that today, the cells in our body would die without the formerly independent mitochondria within.

In other words, contrary to the popular idea of all living things being fiercely competitive against one another, there is evidence of as much cooperation as competition among many life forms, much as Professor Cannadine contends in regard to our own species.