Another topic of controversy in the field of romantic relationships is that of domestic abuse. Following the theory that romantic love evolved as a byproduct of survival, it can be said that in some instances, it has turned into a maladaptation. Oxytocin is a neurophysical hormone produced in the brain. It is known to cause a decrease in stress response. It also can cause an increase in feelings of attachment. In the beginning stages of a romantic relationship, OT levels surge and then remain relatively stable over the duration of the relationship. The higher the surge of OT, the greater the likelihood is of partners staying together. It plays an important role in increasing positive interpersonal behaviors such as trust, altruism, empathy, etc. This response is not universal and can in fact, cause the opposite to occur depending on environment and individual. Individuals ranked high in rejection sensitivity exhibited aggressive tendencies and decreased willingness for cooperation, indicating a link between oxytocin and relationship maintenance.