"COMPARATIVE REPRODUCTIVE ANATOMY OF THE HUMAN AND TAMARANEAN" or "WHY STARFIRE HAS A DICK" My theory, at least. Doubt we'll ever see actual proof. The reproductive anatomy of the human and Tamaranean races are rather similar, much like the superficial overall anatomy of the two species. While physiologically compatible (i.e., "tab A fits into slot B," as it were), the genetic and microbiological differences between the species make successful crossbreeding attempts unlikely without genetic engineering work conducted. MALE: The reproductive anatomy of the Tamaranean male is grossly quite similar to that of the human male, with an external penis used for excretion and copulation, and external testicles within a scrotum. There are, however, notable differences. The glans, or "head" of the Tamaranean penis is notably more bulbous than that of the human male, due to the fact that the organ is constructed somewhat differently. Whereas in the human male, the urethra is also used for the discharge of semen at orgasm, the Tamaranean penis has a separate "seminal duct" running along the underside of the shaft and penetrating through the glans to emerge at roughly the same location as the human urethra. The Tamaranean male's urethra, unlike the human one, is located along the centerline of the penis, causing the more hemispherical shape of the Tamaranean glans. One result of this is that there is no need for the prostate gland to provide a salty base for the Tamaranean ejaculate (necessary in humans to neutralize residual uric acid in the urethra). As a result, the Tamaranean prostate gland is significantly smaller than that of a human male, dedicated almost entirely to the production of high-energy sugars incorporated into the ejaculate to increase the stamina of the sperm following orgasm; the remaining portion of the prostate gland has adapted into the hub of a dedicated reproductive immune system that efficiently prevents infection through the male reproductive organs. As a consequence, sexually transmitted disease is extremely rare among Tamaraneans. (As a side note, the lack of the salty base in Tamaranean ejaculate has anecdotally been described as making the ejaculate taste like the syrup used to make carbonated soft drinks, as compared to the generally salty taste of human ejaculate. No clinical studies are planned to confirm this.) Other differences are less visible. Circumcision is virtually unknown among Tamaranean males, as the seminal duct takes the space where the foreskin's frenulum is located on the human male, making removal impossible without leaving the subject sterile. Tamaranean testicles are less sensitive to heat than human ones, so the scrotum is smaller and holds them closer to the body, providing better protection from impact. While Tamaraneans do grow pubic hair in the genital areas, no pubic hair grows on the genitals themselves, or on the scrotum in males. The reason for this difference from humans is unclear. The Tamaranean male's arousal cycle is essentially identical to that of human males, as is the response to sexual stimulation, though the semi-exposed portion of the seminal duct is significantly less sensitive than the frenulum of uncircumsized human males. The Tamaranean penis tends to be somewhat longer than the human penis, averaging 20 centimeters long when fully erect, as opposed to 15 centimeters for humans. However, the Tamaranean penis is proportionally thinner than the human penis, with virtually identical average circumference measurements. This variation is believed by some to be an adaptation to the presence of the Tamaranean female's pseudopenis, though this is disputed by many, particularly those who profess a preference for rear-entry sexual positions. (For diagrams of the human male's reproductive anatomy, see http://www.mhhe.com/socscience/sex/common/ibank/ibank/0044.jpg , http://www.mhhe.com/socscience/sex/common/ibank/ibank/0045.jpg , and http://www.mhhe.com/socscience/sex/common/ibank/ibank/0050.jpg. Diagrams of the Tamaranean male reproductive anatomy are not currently available.) FEMALE: Interestingly, despite the apparent superficial differences between the reproductive anatomy of the human female and the Tamaranean female, there is little functional difference between the two, with an internal vagina, uterus, and ovaries. The most obvious difference between the Tamaranean female and the human female is the existance of the Tamaranean pseudopenis. The pseudopenis is an organ currently believed to be unique to the Tamaranean species, and merits some discussion. Superficially, the pseudopenis resembles a human or Tamaranean male's penis, extending from a location typically about two to three centimeters above the vaginal opening. While the pseudopenis has a glans (head) that is visibly different from the shaft, it lacks the coronal ridge found at the base of the glans on the male penis. The pseudopenis also lacks a true foreskin, though some examples have a short flap of loose skin that overlaps the intersection of the glans and the shaft, possibly representing a vestigial foreskin. The pseudopenis contains the Tamaranean female's urethra, which extends to the tip of the glans, exactly as the penis does on human and Tamaranean males. Likewise, its shaft is composed largely of erectile tissue that becomes erect with sexual arousal. The nearest human female analogue to the Tamaranean pseudopenis would be the clitoris, though the clitoris is significantly smaller, located in a different place, and does not contain the urethra. The pseudopenis is similar in size to the human male's penis, averaging 15 centimeters long when fully erect, and twelve centimeters in circumference. Continuing down from the pseudopenis, the reproductive anatomy of the Tamaranean female becomes more like that of the human female. The outer labia start a bit further down on the Tamaranean female, as there is no vaginal urethral opening. The Tamaranean female lacks a clitoris, its functions being carried out by the pseudopenis. Inside the outer labia are found the inner labia and the vaginal opening itself. Tamaranean females do not have a hymen of any sort, as with most known mammalian species in the galaxy. This has resulted in further questioning of the purpose of the hymen on the human female. Internally, the Tamaranean female's reproductive anatomy is nearly identical to that of the human female. The ovaries and fallopian tubes are located within a centimeter of their locations on the human female, and serve the same purpose. The vagina itself is slightly shorter, on average, than the human vagina, but the cervix, unlike the human cervix, is designed to be penetrated by the penis during intercourse, dilating as much as ten centimeters with sexual arousal. Interestingly, this action is inhibited during pregnancy, causing most Tamaranean females to find vaginal intercourse during pregnancy to be extremely unpleasant. The so-called "Graftenberg Spot" or "g-spot" of the human female does not have an actual analogue in the Tamaranean female. Instead, the entire vaginal wall is much more sensitive to stimulation than that of the human female. It is speculated that this variation evolved due to the lack of a clitoris to be directly stimulated during intercourse. Interestingly, while Tamaranean females describe stimulation of the vaginal wall to feel "truly amazingly wonderful," stimulation of the vaginal wall does not actually lead to orgasm directly. Tamaranean females can only acheive orgasm through stimulation of the pseudopenis. The nearest human equivalent would seem to be the nipples, which, while sensitive and capable of generating sexual arousal, are not able to directly bring orgasm. (For what it's worth, Tamaranean nipples, both male and female, are generally slightly less sensitive to sexual stimulation than human nipples.) Tamaranean females continuously secrete a small amount of lubricating mucus through the vaginal walls. During sexual arousal, the rate of secretion increases immensely, providing the lubrication required to protect the vaginal walls from friction during intercourse. Additionally, during arousal, the same lubricating mucus is secreted through the meatus (urethral opening) of the pseudopenis, providing lubrication to the glans. At orgasm, the pseudopenile secretion becomes violent, resulting in a pseudoejaculation of lubricating mucus. In an interesting variation from the norm for mammalian species, while Tamaranean females do go through a regular estrus cycle (averaging every 39 days, 17 hours by Earth time standards, or every 36 Tamaranean days), there is no menstrual cycle. This is because the Tamaranean female does not automatically ovulate during her fertile period of approximately nine Earth days. As with many sentient mammalian species, the Tamaranean female's libido greatly increases during estrus. To reproduce, the Tamaranean female must be brought to orgasm through stimulation of the pseudopenis. During her estrus period, orgasm triggers ovulation in the Tamaranean female. Only the initial orgasm results in ovulation. Failure to conceive within approximately 21 Earth hours results in the ovum being reabsorbed into the body. Reabsorption is complete within seven hours after it starts, and the body has "reset" and is again able to ovulate within another four hours. In the event of successful conception, the ovum emits chemical signals that are detected by receptors in the uterine wall and trigger an immediate hormonal response that shifts the body into gestation mode within two hours. While unusual for sentient mammalian species, sexually-triggered ovulation is not unheard of. Earth felines are one example of mammals that require sexual stimulation to induce ovulation. The Tamaranean estrus cycles do not end with age, as in humans. However, at the end of her childbearing years, a number of less-drastic changes do occur in the Tamaranean female. Her libido during estrus decreases significantly, while her nonfertile periods see an increased libido, though still not as high as during estrus. More importantly, she loses the ability to ovulate as her ovaries end production of fresh ova. Interestingly, though she is no longer able to ovulate on her own, she retains the ability to carry a child right up until her death. The reasons for this are unclear. (Diagrams of the human female reproductive system may be found at http://www.mhhe.com/socscience/sex/common/ibank/ibank/0007.jpg , http://www.mhhe.com/socscience/sex/common/ibank/ibank/0008.jpg , and http://www.mhhe.com/socscience/sex/common/ibank/ibank/0009a.jpg . Diagrams of the Tamaranean female reproductive system are not currently available.) SEXUAL BEHAVIOR The anatomical similarities between the Tamaranean male and female have resulted in a very different attitude towards sexuality in Tamaranean culture from that prevalent in human cultures. The presence of the pseudopenis and the requirement to stimulate it to orgasm for reproduction have resulted in a culture in which homosexual acts are considered healthy and normal, providing both genders with both pleasure and good practice for satisfying potential reproductive partners. In addition, anal intercourse, with both genders taking both the role of the penetrator, and the penetratee, is a common practice, due to the concentration of pleasure nerves in the rectum and anus. A spirited, but friendly, debate has raged on Tamaran for centuries regarding whether oral-genital stimulation or anal intercourse is more effective at bringing either gender to orgasm. An interesting side-effect of the attitude that homosexual acts are normal and healthy is the fact that non-monogamous relationships are quite common in Tamaranean culture. It is not at all uncommon to find permanent group relationships, with all members of the group considered partners to all other members of the group. Even in cases where a monogamous heterosexual relationship is maintained, it is considered normal for each member to have a number of homosexual lovers, who sometimes are invited to participate in sex acts involving both members of the monogamous relationship. Such group sex acts are not seen as violating the monogamous relationship, which is often not intended to be a permanent situation in any event. [Excerpted from "Comparative Anatomy and Sexual Sociology of the Human and Tamaranean Species" by J. Smith, M.D., Ph.D., 2002]