As a 27-year-old woman in Philadelphia put it: “I have insecurities that make fun bar flirtation very stressful. I don’t like the Is he into me? moment. I use dating apps because I want it to be clear that this is a date and we are sexually interested in one another. If it doesn’t work out, fine, but there’s never a Is he asking me to hang as a friend or as a date? feeling.” Other people said they liked the fact that on an app, their first exchanges with a prospective date could play out via text rather than in a face-to-face or phone conversation, which had more potential to be awkward.
To the relief of many parents, educators, and clergy members who care about the health and well-being of young people, teens are launching their sex lives later. From 1991 to 2017, the Centers for Disease Control and Prevention’s Youth Risk Behavior Survey finds, the percentage of high-school students who’d had intercourse dropped from 54 to 40 percent. In other words, in the space of a generation, sex has gone from something most high-school students have experienced to something most haven’t. (And no, they aren’t having oral sex instead—that rate hasn’t changed much.)
During ovulation, the ovum travels down the Fallopian tubes to the uterus. These extend about four inches (10 cm) from both sides of the uterus. Finger-like projections at the ends of the tubes brush the ovaries and receive the ovum once it is released. The ovum then travels for three to four days to the uterus.[page needed] After sexual intercourse, sperm swim up this funnel from the uterus. The lining of the tube and its secretions sustain the egg and the sperm, encouraging fertilization and nourishing the ovum until it reaches the uterus. If the ovum divides after fertilization, identical twins are produced. If separate eggs are fertilized by different sperm, the mother gives birth to non-identical or fraternal twins.
At least for humans, this most basic of acts is anything but basic. As the pioneering sex researcher Alfred Kinsey put it, the only universal in human sexuality is variability itself. From attraction to action, sexual behavior takes many forms. Human interest in sex is not a matter left to chance but more a built-in imperative; survival of the species depends on it. The decks are stacked in sex's favor, as a passport to bonding, to intimacy, to pleasure, and even to human growth and healing. Bodies and interests change over the course of time, and the complexities of physiology and psychology mean that most people experience a sexual problem at some point in their lives. Although sex can be one of the most difficult topics for partners to discuss, it's one that also stands to draw couples closer together. The moral and political implications of sex vary greatly from culture to culture, and even within cultures and over time; still, there is agreement on one certainty: It's why we're alive today and what future generations depend on.