Instruct: Given a question, retrieve documents that can help answer the question.
Query: Do all female mammals menstruate?
Menstruation in mammals is the shedding of the uterine lining (endometrium). It occurs on a regular basis in uninseminated[1] sexually reproductive-age females of certain mammal species.
Most female mammals have an estrous cycle, yet only ten primates species, four bats species, the elephant shrew, and the spiny mouse have a menstrual cycle.[17][18] The relatedness of these groups suggests that four distinct evolutionary events have caused menstruation to arise.[19]
The word "menopause" was coined specifically for human females, where the end of fertility is traditionally indicated by the permanent stopping of monthly menstruations. However, menopause exists in some other animals, many of which do not have monthly menstruation;[99] in this case, the term means a natural end to fertility that occurs before the end of the natural lifespan.
Retrograde menstruation alone is not able to explain all instances of endometriosis, and additional factors such as genetic or immune differences need to be invoked to account for the fact that many women with retrograde menstruation do not have endometriosis. In addition, endometriosis has shown up in people who have never experienced menstruation including men,[41] fetuses,[42] and prepubescent girls.[43][44] Further detracting from the retrograde menstruation theory are cases of endometriosis showing up in the brain[45] and lungs.[46] This theory has numerous other associated issues.[47]
Many have questioned the evolution of overt menstruation in humans and related species, speculating on what advantage there could be to losing blood associated with dismantling the endometrium rather than absorbing it, as most mammals do.
Aviva Briefel states that menstruation is the start of monstrosity. Once a girl has reached puberty she is seen to be monstrous. Horror films feed into the female monsters identity through her menstruation. This then states that having your period makes you weaker. The overall objective in Briefel's article, "Monster Pains: Masochism, Menstruation, and Identification in the Horror Film", is that the female monster is unable to control her emotions when pain occurs, whereas male monsters are unable to feel pain.
Most female mammals have an estrous cycle, yet only ten primates species, four bats species, the elephant shrew, and the spiny mouse have a menstrual cycle.[53][54] The relatedness of these groups suggests that four distinct evolutionary events have caused menstruation to arise.[55]
All higher mammals (excluding monotremes) share two major adaptations for care of the young: live birth and lactation. These imply a group-wide choice of a degree of parental care. They may build nests and dig burrows to raise their young in, or feed and guard them often for a prolonged period of time. Many mammals are K-selected, and invest more time and energy into their young than do r-selected animals. When two animals mate, they both share an interest in the success of the offspring, though often to different extremes. Mammalian females exhibit some degree of maternal aggression, another example of parental care, which may be targeted against other females of the species or the young of other females; however, some mammals may "aunt" the infants of other females, and care for them. Mammalian males may play a role in child rearing, as with tenrecs, however this varies species to species, even within the same genus. For example, the males of the southern pig-tailed macaque ("Macaca nemestrina") do not participate in child care, whereas the males of the Japanese macaque ("M. fuscata") do.
In the Torah (Leviticus 15:19-30), a menstruating female is considered ritually unclean - "anyone who touches her will be unclean until evening" (New International Version). Touching a menstruating female, touching an object she had sat on or lain on, or having intercourse with her also makes a person ritually unclean. The extent to which these rules are observed in modern Judaism varies depending on the degree of conservatism/orthodoxy.
Most Christian denominations do not follow any specific rituals or rules related to menstruation. Some denominations follow the rules laid out in the Holiness Code section of Leviticus, somewhat similar to the Jewish ritual of Niddah.
For example, Martin notes that our perception on menstruation is usually negative and misogynistic. We tend to think menstruation as a failure, because the egg is not fertilized and the woman’s uterine tissues begin to “break down” or “slough off". Martin ascribes this perception to linguistic and cultural gender bias - words used to describe menstruation imply failure, dirtiness, structural breakdown and destruction, and wound. (By contrast, we do not perceive the shedding of the stomach lining as a structural failure.) This wound perception is reinforced by the fact that, during menstruation, the woman bleeds and may suffer from pain and discomfort. Martin contends that menstruation is a normal physiological function and process (not a dirty thing or a “secret illness”), which should be viewed as a success - i.e., the success of the female body in avoiding pregnancy, the success of the female body in ridding itself of potentially harmful material from the uterus. Yet, our language and culture prevent this. Such gender bias is also responsible for our tendency to “praise” males for their “amazing” ability to produce a huge amount of sperm, despite of the fact that the sperm is a lot cheaper, biologically, to produce compared to the egg, and the sperm suffer an extremely high mortality in the female reproductive tract. (Robbins and Larkin, 2007: 255)
In the United States, public schools have a sex education program that teaches girls about menstruation and what to expect at the onset of menarche (often this takes place during the 4th grade). Historically menstruation has been a social taboo and girls were taught about menarche and menstruation by their mothers or a female role model. Then, and to an extent now, menstruation was a private matter and a girl's menarche was not a community phenomenon.
The female will ovulate spontaneously and be receptive to the male to be bred (express estrus) at regular biologically defined intervals. The female is receptive to males only while experiencing estrus.
Orangutans also lack visible signs of impending ovulation.[14] Also, it has been said that the extended estrus period of the bonobo (reproductive-age females are in heat for 75% of their menstrual cycle) [15] has a similar effect to the lack of a "heat" in human females.[16]
Perimenopause is when fertility in a female declines, and menstruation occurs less regularly in the years leading up to the final menstrual period, when a female stops menstruating completely and is no longer fertile. The medical definition of menopause is one year without a period and typically occurs between 45 and 55 in Western countries.[4][10]:p. 381
In Buddhism (Theravada or Hinayana) menstruation is viewed as ""a natural physical excretion that women have to go through on a monthly basis, nothing more or less"". However, in certain branches of Japanese Buddhism, menstruating women are banned from attending temples.
In Nichiren Buddhism (Japan) menstruation is not considered a spiritual obstacle to religious practice, although a menstruating woman may choose not to bow, for comfort.
In Hinduism, menstruating women are traditionally advised rules to follow. During menstruation, women are advised not to “enter temple,work in kitchen,wear flowers, have sex, touch other males or females.” Menstruation is seen as unclean, and are often separated from place of worship or any object pertaining to it, for the length of their period.
According to popular belief as women menstruate, which is a sign of fertility, so also Mother Earth menstruates. So all three days of the festival are considered to be the menstruating period of Mother Earth. During the festival all agricultural operations remain suspended. As in Hindu homes menstruating women remain secluded because of impurity and do not even touch anything and are given full rest, so also the Mother Earth is given full rest for three days for which all agricultural operations are stopped. Significantly, it is a festival of the unmarried girls, the potential mothers. They all observe the restrictions prescribed for a menstruating woman. The very first day, they rise before dawn, do their hair, anoint their bodies with turmeric paste and oil and then take the purificatory bath in a river or tank. Peculiarly, bathing for the rest two days is prohibited. They don't walk bare-foot do not scratch the earth, do not grind, do not tear anything apart, do not cut and do not cook. During all the three consecutive days they are seen in the best of dresses and decorations, eating cakes and rich food at the houses of friends and relatives, spending long cheery hours, moving up and down on improvised swings, rending the village sky with their merry impromptu songs.
A few mammals do not experience obvious, visible signs of fertility (concealed ovulation). In humans, while women can learn to recognize their own level of fertility (fertility awareness), whether men can detect fertility in women is debated; recent studies have given conflicting results.[12][13]
Although there is some disagreement in definitions between sources, menstruation is generally considered to be limited to primates. Overt menstruation (where there is bleeding from the uterus through the vagina) is found primarily in humans and close relatives such as chimpanzees.[2] It is common in simians (Old World monkeys, and apes), but completely lacking in strepsirrhine primates and possibly weakly present in tarsiers. Beyond primates, it is known only in bats and the elephant shrew.[3][4][5][6]
The How and the Why is a play by Sarah Treem who was a staff writer for HBO's "In Treatment". The play depicts two women biologists meeting for the first time, one near the end of her career and the other at the beginning. The older woman has earned fame for her work on the Grandmother hypothesis. The younger wants to present a radical new hypothesis to explain why human females menstruate while most mammals do not. The play deals with the workings of science and its impact on the personal lives of women scientists.
All female placental mammals have a uterine lining that builds up when the animal is fertile, but is dismantled (menstruated) when the animal is infertile. Some anthropologists have questioned the energy cost of rebuilding the endometrium every fertility cycle. However, anthropologist Beverly Strassmann has proposed that the energy savings of not having to continuously maintain the uterine lining more than offsets energy cost of having to rebuild the lining in the next fertility cycle, even in species such as humans where much of the lining is lost through bleeding (overt menstruation) rather than reabsorbed (covert menstruation).[2][20] However, even in humans, much of it is re-absorbed.
When Profet won a MacArthur Fellowship in 1993, international media took notice. "New York Times" reporter Natalie Angier called Profet's theory that menstruation protected some female mammal's reproductive canals a "radical new view". "Scientific American," "Time," "Omni," and even "People Magazine" all followed with in-depth profiles of the 35-year-old "maverick" scientific prodigy.
Many religions have menstruation-related traditions, for example: Islam prohibits sexual contact with women during menstruation in the 2nd chapter of the Quran. Some scholars argue that menstruating women are in a state in which they are unable to maintain wudhu, and are therefore prohibited from touching the Arabic version of the Qur'an. Other biological and involuntary functions such as vomiting, bleeding, sexual intercourse, and going to the bathroom also invalidate one's wudhu.[46] In Judaism, a woman during menstruation is called Niddah and may be banned from certain actions. For example, the Jewish Torah prohibits sexual intercourse with a menstruating woman.[47] In Hinduism, menstruating women are traditionally considered ritually impure and given rules to follow. During menstruation, women are not allowed to “enter the kitchen and temples", wear flowers, have sex, touch other males or females.”[48] Western civilization, which has been predominantly Christian, has a history of menstrual taboos.
Many have questioned the evolution of overt menstruation in humans and related species, speculating on what advantage there could be to losing blood associated with dismantling the endometrium, rather than absorbing it, as most mammals do. Humans do, in fact, reabsorb about two-thirds of the endometrium each cycle. Some work asserts that overt menstruation occurs not because it is beneficial in itself. Rather, the fetal development of these species requires a more developed endometrium, one which is too thick to reabsorb completely. There is a correlation between species that have overt menstruation to those that have a large uterus relative to the adult female body size.[56]
This hypothesis has received much criticism. For example, as all mammals experience the same immune system responses to sperm antigens, this hypothesis predicts that all mammals should exhibit extended female sexuality. However, only few species of mammals exhibit sexual behaviour outside the conceptive period.
Females of other species of placental mammal undergo estrous cycles, in which the endometrium is completely reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. Many zoologists regard this as different from a "true" menstrual cycle. Female domestic animals used for breeding —for example dogs, pigs, cattle, or horses— are monitored for physical signs of an estrous cycle period, which indicates that the animal is ready for insemination.