Content Warning: The guide discusses suicide, rape, and sexual assault, which are present in the source text.

One of the main themes of the novel is the idea that otherness is constructed by humans to let one group dominate another. Lilith learns that one of the primary reasons that humanity was fated to destroy itself is its innate hierarchical nature—its unavoidable tendency to view all people in terms of status. This also leads to prejudice against those seen as outsiders who belong to a different group. When confronted with the extreme otherness of the physical appearance of the Oankali, humans reject them outright. Filled with disgust and revulsion, they attack the Oankali and try to destroy them, which is humanity’s response to outsiders it considers hostile.

The Oankali, by contrast, value difference and seek it out. To promote their survival as a species, they must continually foster diversity and cultural pluralism in themselves. They need genetic adaptation to survive, so they “trade” with other species to incorporate new genetic traits. Lilith is chosen to be the “parent” of the human group because of her ability to adapt to her new culture. They hope she can be the liaison between humans and Oankali.