The sexual selection theory has been criticized, however, for its neglect of emotional attachment. People seek out a romantic partner not only for sexual satisfaction, but also for emotional support and fulfillment. In both Buss’s and Sternberg and Gracek’s studies, attachment-related traits, such as kindness and understanding, were listed by both sexes as the most important considerations in romantic relationships. Moreover, these findings appear to be valid across cultures, as Buss collected his data from thirty-seven different cultures. According to Cindy Hazan and Lisa Diamond, attachment bonds between sexual partners, otherwise known as romantic love, may be just as important to evolution as sexual selection.