The resulting cooperation encourages collective tasks that promote the survival of each member of the group. It may be that sex reinforces intimate social bonds between individuals to form larger social structures. In these animals, the use of sex has evolved beyond reproduction to serve additional social functions. Humans, bonobos and dolphins are all intelligent social animals, whose cooperative behavior proves far more successful than that of any individual alone. The emotional attachment between the partners, encouraging them to stay together over a long term, often allows them to support each other in cooperative tasks, such as raising their offspring. There is said to be a functional advantage to sex anytime for social reasons rather than reproductive ones. In both humans and bonobos the female undergoes relatively concealed ovulation, so that males generally do not know whether she is fertile at any given moment. That is not to say that homosexuality and non-reproductive heterosexuality are limited to these three species rather, they are unusual for female receptivity to sex independent of estrus. Likewise, all three sometimes engage in homosexual behaviors.
All three engage in heterosexual behaviors even when the female is not in estrus, that is, at a point in her reproductive cycle suitable for successful impregnation.
Humans, bonobos and notably dolphins are all species known to have non-reproductive sex, apparently for the sake of pleasure. The missionary position is the most commonly used position for sexual intercourse in humans The cowgirl sex position is a position frequently combined with kissing, caressing, and embracing of the paramour. Heterosexual intercourse (coitus), where both participants are believed to be fertile, should always be considered likely to result in pregnancy, unless adequate contraceptive ( birth control) measures are taken. When a fertilized ovum reaches the uterus, it becomes implanted in the lining of the uterus, known as endometrium and a pregnancy begins. When a fertile ovum from the female is present in the fallopian tubes, the male gamete joins with the ovum resulting in fertilization and the formation of a new embryo. Millions of sperm are present in each ejaculation, to increase the chances of one fertilizing an egg or ovum. The subsequent route of the sperm from the vault of the vagina, is through the cervix and into the uterus, and then into the fallopian tubes.
During ejaculation, which normally accompanies male orgasm, a series of muscular contractions delivers semen containing male gametes known as sperm cells or spermatozoa into the vault of the vagina. Penetration with the penis is also known as intromission, or by the Latin name immissio penis.Ī detailed description of the physiology of sexual arousal and orgasm can be found in the article Human sexual response cycle.Ĭoitus is the basic reproductive method of humans. In this way, they stimulate themselves and each other until orgasm and ejaculation are achieved.
To engage in sexual intercourse, the erect penis is inserted into the vagina and one or both of the partners move their hips to move the penis backward and forward inside the vagina to cause friction, typically without fully removing the penis. "Genital sex" as used here refers to genito-genital sex, among BDSM/fetish practitioners the term "genital sex" can mean any sex involving the genitals including anal, oral, manual, etc., as opposed to those based on toys, costumes or fantasies.Ĭoitus may be preceded by foreplay, which leads to sexual arousal of the partners, resulting in the erection of the penis and natural lubrication of the vagina. See the terms frot for male-male genital sex and tribadism for female-female genital sex. See Human sexual behavior for a discussion of the broader sense of sexual intercourse and list of sexual positions for the wide variety of sexual activities that exist.
The term sexual intercourse refers to a wider range of sexual activities than the term coitus, which only refers to male-female genital sex. Sexual intercourse, specifically coitus, is the human form of copulation. 1492) is an artist's interpretation of what happens inside the body during coitus by Leonardo da Vinci. For biological copulation in general, see copulation.Ĭoition of a Hemisected Man and Woman (c. The term "act of union" is used as a euphemism for sexual intercourse This article is about sexual intercourse in humans and its societal implications.