Adaptation occurs when living beings respond to changes in their environment to enhance their chances of survival. Burke Harris believes that the poor health outcomes of her patients result from adaptations—ones that are effective responses to short-term stressors like violence—that become maladaptive (harmful) because her patients are so often exposed to stressors.

An adverse childhood experience (ACE) is a traumatic event that can shape a child’s physical and mental health throughout the remainder of that person’s life. Examples of ACEs are divorce or separation of one’s parents, having an incarcerated parent, having a caretaker with a psychological illness or chemical dependency, or surviving any form of abuse (physical, sexual, or verbal). Burke Harris’s work in Bayview convinces her that significant numbers of ACEs are drivers of long-term stress responses that result in poor health outcomes for her patients. (See the two survey instruments in the book’s appendices.)

Biological determinism is the idea that things like genetics or one’s body determine how one behaves. Important critiques of biological determinism include that using it as a lens may ignore the influence of the environment and that it often encourages unquestioning acceptance of discriminatory ideas about oppressed groups. As her ideas became more visible, Burke Harris was forced to confront critics who believed her emphasis on ACEs and toxic stress reinforced the concept of biological determinism; community activists believed she was labeling children dealing with ACEs as brain damaged, thus taking attention away from activists’ fight to improve the environment (political and physical) that leads to poor outcomes.