Cosmos

In the face of the vastness and variety of the Cosmos, humanity should be humbled into examining our impact on our unique planet, Earth. The evolution of life on this planet has inevitably been affected by human desires. In addition, the continuation of life on Earth is inevitably influenced by human actions; events such as mass extinctions, climate change, and geopolitical conflict are the direct result of human decisions. There are consequences—both local and cosmological—for how humanity determines to interact with the Earth, with the larger universe, and with its own species. In the end, Sagan provides a message of hope for the future.

Sagan explains how human choices affect other creatures through a succinct example. Japanese legend holds that Heike warriors, decimated by a rival samurai group, wander the bottom of the ocean as crabs, identifiable by a specific pattern on the crab shell. Although “The Heike almost vanished from history,” because some crabs have carapaces “that disturbingly resemble the face of a samurai” (25), they have been preserved—not eaten, but thrown back to thrive in the sea. In this way, humans have changed crab evolution and this ecosystem: One type of crab thrives because humans decided that they resemble other humans; by the process of artificial selection, we directly control their environment.

Human expansion into the environment and the advancement of technology have negative impacts. Sagan addresses climate change long before the topic’s political prominence: “we have also been perturbing the climate in the opposite sense. For hundreds of thousands of years human beings have been burning and cutting down forests and encouraging domestic animals to graze on and destroy grasslands” (103). He is also clear that the geopolitical state of the Earth leaves much to be desired. From the burning of the great library of Alexandria to the Cold War, humanity has revealed a desire for destruction and chaos for the benefit of nation-states or systemic belief systems. During the writing of Cosmos, the most pervasively worrying problem was the possibility for nuclear war: “Every major power has some widely publicized justification for its procurement and stockpiling of weapons of mass destruction, often including a reptilian reminder of the presumed character and potential defects of potential enemies” (329). Sagan often reminds his readers that they are, actually, “one species” (332), hoping to significant curb the most destructive impulses that fuel the decimation of the environment and the possibilities for widespread, inevitably devastating warfare.

Sagan emphasizes that there is always hope for a better, more peaceful future, wherein scientific endeavors keep the Earth connected to the larger cosmos. First, humanity has a responsibility to continue to explore the universe, which cannot be done in the face of nuclear warfare or environmental destruction. He implores his readers to consider that, even if intelligent life is found elsewhere in the cosmos, “There will be no humans elsewhere. Only here” (339). Humanity is unique to the universe, he suggests, and thus has intrinsic value. Further, he appeals to his audience to call upon their best sensibilities: “If we survive, our time will be famous for two reasons: that at this dangerous moment of technological adolescence we managed to avoid self-destruction; and because this is the epoch in which we began our journey to the stars” (339). What better reason to preserve humanity than such a magnificent journey?