Asexuality is not a new aspect of human sexuality, but it is relatively new to public discourse. In comparison to other sexualities, asexuality has received little attention from the scientific community, with quantitative information pertaining to the prevalence of asexuality low in numbers. S. E. Smith of "The Guardian" is not sure asexuality has actually increased, rather leaning towards the belief that it is simply more visible. Alfred Kinsey rated individuals from 0 to 6 according to their sexual orientation from heterosexual to homosexual, known as the Kinsey scale. He also included a category he called "X" for individuals with "no socio-sexual contacts or reactions." Although, in modern times, this is categorized as representing asexuality, scholar Justin J. Lehmiller stated, "the Kinsey X classification emphasized a lack of sexual behavior, whereas the modern definition of asexuality emphasizes a lack of sexual attraction. As such, the Kinsey Scale may not be sufficient for accurate classification of asexuality." Kinsey labeled 1.5% of the adult male population as "X". In his second book, "Sexual Behavior in the Human Female", he reported this breakdown of individuals who are X: unmarried females = 14–19%, married females = 1–3%, previously married females = 5–8%, unmarried males = 3–4%, married males = 0%, and previously married males = 1–2%.