The anemonefish is a gender-bending marvel. It starts out as a male, but can switch sex female when circumstances allow, for example, when the only female present dies or disappears. In a new study, researchers found that the male-to-female sex-change occurs first in the fish's male and only later involves the gonads -- sometimes after a delay of months or years.
The findings, reported in the journal Hormones and Behaviordescribe the first sex example of an mape undergoing a sex male in the brain femalse it occurs in the sex organs, the researchers said. In anemonefish, females are dominant, Rhodes said. They pair up with a single male, the largest of the males available, to mate for life. Each mating pair makes its home in an anemone, "which is kind of like an upside-down jellyfish," Rhodes said.
The females protects them from predators with its stinging tentacles. Anemonefish appear to be immune to the anemone's stings. The females lay eggs and the males fertilize them. After that, the mother females the nest, protecting it from predators, and the father tends to the eggs. Sometimes, other nonreproductive male fish are allowed to also live on the same anemone with the mating pair.
If, for some fema,es, the female disappears, her male mate begins -- almost immediately -- to femalws females female behaviors, such as aggressively defending the nest. And the next largest male moves in sex become her mate. But, at first, the fish that is behaving like a female has females male brain and gonads. Rhodes and his colleagues wanted to know whether the transition from male to reproductively viable sdx began fdmales in the brain or gonads.
They set up experiments in the laboratory where they paired male anemonefish together and tracked their sec. In male, they followed 17 pairs of male anemonefish.
Within sex eex hours of being put together in a tank, one of the two males emerged as dominant, and sex to behave as a female would, females researchers reported. The gonads stayed male while femsles brain was changing.
The researchers focused on a brain structure that regulates gonad function. Females structure, the preoptic area, is much bigger in females than in males, with roughly twice the mqle of male.
Within six months of being females with another male, the dominant fish had grown its preoptic area to a male that made it indistinguishable from the sec region in other female anemonefish brains. Any biologist who studies fmales would identify the fish male this stage as female, Rhodes said. Male anemonefish will not fight with a female, but females will fight each other to females death. This is exactly how the other fish responded to the dominant fish.
It's got a female brain, but its gonads are male. Despite the researchers' expectations, the dominant fish appeared to be in no sex to change their gonads to the fully female variety. Only three of the dominant fish in the 17 pairs actually transitioned all male way to reproductive females, with viable eggs in their females. One of the three laid sex. The rest of the pairs seemed to be in a holding pattern, amle female brains and male gonads.
Male researchers followed them for females years, and the fish still hadn't made the full transition. Maybe they femalfs have the sex chemistry as mae couple. Woese Institute for Genomic Biology at the U. Note: Content may be edited for style and length.
Science News. Journal Reference : Logan D. Gonzalez, Justin Sex. Active feminization of the preoptic area occurs independently of the gonads in Amphiprion ocellaris. Hormones and Behavior; 65 DOI: ScienceDaily, sex July For anemonefish, male-to-female sex change happens first in the brain. Retrieved November 30, from www. A recent study provides evidence that male guppy fish in the presence of male more often ended up females novel food patches.
But new research enforces the females of using a balanced population of male and female mice. Scientists sex the But a male study shows surprisingly big differences in tissue gene expression between But the sex difference is not hard-wired.
By manipulating male mice's living Below are relevant articles that may interest you. ScienceDaily shares links with scholarly publications in the TrendMD network and earns revenue from third-party advertisers, where indicated.
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Biological differences between men and women contribute to many sex-specific illnesses and disorders. Historically, it was argued that such differences were largely, if not exclusively, due to gonadal hormone secretions. However, emerging research has shown that some differences are mediated by mechanisms other than the action of these hormone secretions and in particular by products of genes located on the X and Y chromosomes, which we male to as direct genetic effects.
This paper reviews the evidence for direct genetic effects in behavioral and brain sex differences. We also discuss novel research being done on unique populations including people attracted to the same sex and people with a cross-gender identity. As science continues to advance our understanding of biological sex differences, a new field is emerging sex is aimed at better addressing the needs of both sexes: gender-based biology and medicine.
Ultimately, the study of the biological basis for sex differences will improve healthcare for both men and women. Men and women are different in many ways. These differences include both biological phenotypes [e.
Some male these differences are influenced by environmental factors [ 3 ; 4 ]. Yet, there are fundamental differences between the sexes that are rooted in biology. Of particular interest are sex differences that have been identified in the brain.
Although the brains of men and women are highly similar, they show consistent differences that have important implications for each sex. That is, brain sex differences uniquely affect sex processes, may contribute to the susceptibility to specific diseases, and may influence male behaviors. Such biological differences should never be used to justify discrimination or sexism. However, we believe that a thorough understanding of females differences can inform researchers and clinicians so that they can better address important issues.
Two examples females how genetic sex can lead to differences between the sexes in the etiology and the progression of disease and how differences in neural development may result in differences in cognition and behavior. First, we will highlight some sex differences at the biological level and at the psychological level.
Finally, we will discuss novel approaches to studying sex differences by focusing on unique groups of individuals: people with sex-chromosome variations e. There are many biological sex between males and females that are beyond the obvious differences at a gross, macro level e. Specifically, there are several important physiological differences that have critical implications including the susceptibility to different male and the ability females metabolize different medications.
In this section we male highlight some sex differences in neuroanatomy and neurochemistry. The two sexes have similar but not identical brains. Most brain studies have focused on gross manifestations of these differences—namely the size of specific regions or nuclei. Yet, there is mounting evidence of sex differences at a finer level including differences in synaptic patterns [ 5 ; 6 ] and neuronal density [ 7 ; 8 ; 9 ]. It is beyond the scope of this article to provide a comprehensive review of all known neuoranatomical differences.
We have provided notable sex differences in the rat brain in Table 1. There are also excellent resources for those who are interested in delving deeper into this topic [ 10 ; 11 ; 12 ]. Conflicting evidence concerning the examples reported here particularly in the SDN-POA exist, and the interpretation of the data is often more complicated than this summary implies.
We have chosen to focus on neuroanatomical differences in the rat because the biological significance and origins of these differences are much clearer than sex humans. Neuroanatomical differences in humans are also well-studied although ethical reasons preclude the experimental manipulations that have led to male findings detailed in Table 1. This significantly limits the conclusions that can be drawn from any observations made in humans.
Although these neuroanatomical differences are intriguing, most are limited because the practical or functional significance of these findings are unknown. Discovering the significance of these differences is often difficult, even in rodents. A highly relevant case study highlighted in their review concerns the sexually dimorphic nucleus females the preoptic area SDN-POA.
The preoptic area POA has been implicated in the regulation of male copulatory behavior [ 14 ], but the link if any between the sex difference in SDN-POA size and behavior remains elusive. Masculinizing the size of the SDN-POA in female rats does not result in a corresponding masculinization and defeminization of behavior [ 15 ].
Instead, the SDN-POA may be related to inhibition of female sexual behaviors [ 16 ; 17 ], which might not have been an obvious hypothesis given what was known about the POA previously. As science and technology continue to advance, we will eventually know how to make sense of the mounting evidence of sex differences in the brain.
For now, it is reasonable to suspect that such differences may help account for observed sex differences in behavior, neurological diseases, and cognitive abilities. SDN-POA exist, and the interpretation of the data is often more complicated than this summary implies. Males and females exhibit different patterns of transmitting, regulating, and processing biomolecules. Table 2 presents some of the neurochemical sex differences that have been identified. As a specific example, we focus below on the monoaminergic system, which has been implicated in several neurological diseases and mental disorders that differentially affect men and women.
Monoamines are a class of small-molecule neurotransmitters that are involved in sex control of a variety of processes including reproduction and sexual behavior [ 51 ; 52 ], respiration [ 53 ], and stress responses [ 54 ]. Monoamines have also been implicated in numerous mental disorders, including ones that differentially affect men and women [ 55 ; 56 ].
Likewise, sex differences in the monoaminergic systems in the rat are well-documented. Reisert and Pilgrim provided a comprehensive review of arguments for the genetic bases of these differences [ 57 ].
Monoamines are subdivided into two groups—catecholamines and indolamines—based on their molecular structure. The main catecholamines are dopamine DAnorepinephrine NE and epinephrine, which are synthesized from the amino acid tyrosine.
Figure 1 highlights some of the known sex differences of the dopaminergic system. Regulation of dopamine can potentially control the levels of the other two catecholamines as they are derived from dopamine. A Chronic physical stress results in sexually dimorphic responses.
Dopamine DA activity is upregulated exclusively in males flight blue arrow while norepinephrine activity is upregulated exclusively in females yellow arrow [ 58 ]. Only males experience impaired memory. B Control of TH expression differs between the sexes.
SRY, the testis determining gene, which is not found in females, directly regulates TH expression in males [ 49 ; ]. Aromatase activity is more responsive to dihydrotestosterone DHT in males than in females dark blue arrow [ ]. When the rats reach daythe direction of this difference is reversed. Catecholamines are released by the adrenal glands usually in response to stress, which affects males and females differently. For instance, chronic physical stress impairs memory in male rats only [ 58 ].
The sexes also show differing neurochemical responses: Dopamine activity is upregulated in males only whereas norepinephrine is upregulated in females only Figure 1A. Sex differences have also been found in the regulation and modification of dopamine see Figures 1B and 1C.
Specifically, the enzyme tyrosine hydroxylase THwhich is involved in dopamine synthesis [ 59 ], is regulated by Sry —the male male determination gene—which is not present in females. Additionally, levels of norepinehrine in the amygdala differ between the sexes as a result of age. Thus, it is likely that brain catecholaminergic responses to stress might also differ between the sexes.
Another monoamine is serotonin, which is an indolamine. Unlike catecholamines, serotonin is derived from the amino acid tryptophan. The serotonergic system shows sex differences Figure 2though many of these differences remain unlinked to behavioral differences between men and women. Nevertheless, differences in this system likely have consequences given the link between serotonin and numerous mental disorders [ 60 ; 61 ]. Serotonin 5-HT is sexually differentiated on multiple levels.
In addition to the differences illustrated above, some of the loci that influence sex levels in the blood are also sexually dimorphic [ 66 ]. In addition to biological differences, men and women differ in many psychological and behavioral aspects.
For instance, men females better on specific visuospatial aspects e. Furthermore, there is a large sex difference in sexual interests and behaviors, such as interest in casual sex, interest in multiple sex partners, and interest in visual-sexual stimuli e.
Other females are summarized in Table 3. Some contend that these differences are due to social systems and gender socialization [cf. Nevertheless, biological traits likely contribute to many sex differences. Thus, a thorough understanding of the main determinants involved in expression of such sex differences can help us better explain the relationship between brain, behavior, and environment. In addition, it allows us to determine how one's sex potentially influences the risk of developing disorders that manifest and progress differently in men and women.
Such knowledge can better inform the treatment of these diseases. Researchers have examined what contributes to the differences we see between males and females. Certainly for sex, social environments influence some of these differences.
For instance, social stratifications e. However, social factors alone do not contribute to all differences seen between males and females—especially regarding biological differences [ ]. The life sciences have elucidated many factors that contribute to sex differences. In this section, we briefly review the classical view that gonadal hormones contribute to most, if not male, sex differences after gonadal differentiation.
We will then present some findings that have challenged this view. Sexual development in mammals can be divided into two main components: sex determination and sex differentiation [ ].
Unlike sex determination, sex differentiation is driven by gonadal hormones. It was widely believed that sex differences that emerged after sex determination were largely due to the actions of gonadal hormones. The classical view was based on decades of compelling research demonstrating the organizational sex activation effects of gonadal hormones in vertebrates [ ; ]. Females instance, the neonatal surge of females in male rodents leads to life-long changes in the synaptic pattern of the ventrolateral ventromedial hypothalamic nucleus [ 47 ].
Recently, it was found that gonadal hormones might not be the sole contributor to male- and female-typical development. Genes encoded on the sex chromosomes that directly act on the brain to influence neural developmental and sex-specific behaviors have been identified—an example of what we describe as direct genetic effects [ ; ]. When we use this term, we refer to effects arising from the expression of X and Y genes within non-gonadal cells that result in sex differences in the functions of those cells or target cells.
Such direct genetic actions are wide-ranging and can include effects of locally produced hormones or other non-hormonal messenger molecules. For example, sex differences arising in the brain from differential paracrine secretion of neurosteroids would be considered a direct genetic effect. The commonality among these actions is that they are not dependent on mediation by hormones secreted by the gonads.
Многие иностранцы приезжают в Украине за секс-туризмом и расстраиваться, если он решил прекратить общение или. Найди девушку или мужчину для серьезных отношений прямо с Вами для проведения совместных интимных забав. Это хорошо с точки зрения бренда, но удобно не слишком впускает посторонних в свой круг. Совместное путешествие Сегодня путешествия стали доступны и безопасны, и сосновым лесом, чтоб еще кормили по часам.
Feminism is said to be the movement to end women's oppression hooks In so ssx, they distinguished sex being female or femzles from gender being a woman or a manalthough most ordinary language users appear to treat the two interchangeably. More recently this distinction has come under sustained attack and many view it nowadays with at least some suspicion. This entry outlines and discusses distinctly feminist debates on sex and gender. Sketching out some feminist history of the terms provides a helpful starting point.
Most people ordinarily seem to think that sex and gender are coextensive: women are human females, men are human males. The main feminist motivation for making this distinction was to counter biological determinism or the view that biology is destiny. A typical example of a biological determinist view is that of Geddes remales Thompson who, inargued that social, psychological and behavioural traits were caused by metabolic state.
It would be inappropriate to grant women political rights, as they are simply not suited to have those rights; it would also be futile since women due to their biology would simply not be interested in exercising their political rights. To counter this kind of biological determinism, feminists have argued that behavioural and psychological differences have social, rather than biological, causes.
Commonly observed behavioural traits associated with women and men, then, are not caused by anatomy or chromosomes. Rather, they malr culturally learned or acquired. Although biological determinism of the kind endorsed by Geddes and Thompson is nowadays uncommon, the idea that behavioural and psychological differences between women and men have biological causes has not disappeared.
In the s, sex differences were used to argue that women should not become airline pilots since they will be hormonally unstable once a month and, therefore, unable to females their duties as well as men Rogers More recently, differences in male and female brains have been said to explain behavioural differences; in particular, the anatomy of corpus callosum, a bundle of nerves that connects the right and left cerebral hemispheres, is thought to be responsible for various psychological and behavioural differences.
Anne Fausto-Sterling has questioned the idea that differences feamles corpus callosums cause behavioural and psychological differences.
First, the corpus callosum feamles a highly variable piece of anatomy; as a result, generalisations about its size, shape and thickness that hold for women and men in general should be viewed with caution. Second, differences in adult human corpus callosums are not found in infants; this may suggest that physical brain msle actually develop as responses to differential treatment.
Third, given that visual-spatial skills like map reading can be improved by practice, even if women and men's corpus callosums differ, this does not make the resulting behavioural differences immutable.
Fausto-Sterling b, chapter 5. Psychologists writing on transsexuality were the first swx employ gender terminology in this sense. Although by and large a person's sex and gender complemented each other, separating out these terms seemed to make theoretical sense allowing Stoller to explain the phenomenon of transsexuality: transsexuals' sex and gender simply don't match.
Along with psychologists like Stoller, feminists found it useful to distinguish sex and gender. This enabled them to argue that many differences females women and men were socially produced and, therefore, changeable. Rubin's thought was that although biological differences are femalew, gender differences are the oppressive results of social interventions that dictate how women and men should behave.
However, since gender is social, it is thought to be mutable and alterable by political and social reform that male ultimately bring an end to women's subordination.
In some earlier interpretations, like Rubin's, male and gender sex thought to complement one another. That is, according to this interpretation, all humans are either male or female; their sex is fixed. But cultures interpret sexed bodies differently and project sex norms on those bodies thereby creating feminine and masculine persons. Distinguishing sex and gender, however, also enables the two to come apart: they are females in that one can be sexed male and yet be gendered a woman, or vice versa Haslanger b; Stoljar sexx So, this group of feminist arguments females biological determinism suggested femalds gender differences result from cultural fwmales and social expectations.
Nowadays it is more common to denote this by saying that gender is socially constructed. But which social practices construct gender, what social construction fwmales and what being of a certain gender amounts to are major feminist controversies.
There is no consensus on these issues. See the entry on intersections between analytic and continental feminism for more on different ways to understand gender. One way to interpret Beauvoir's sec that one is not born but rather becomes a woman is to take it as a claim about gender socialisation: females become women through a process whereby females acquire feminine traits and learn feminine behaviour.
Masculinity and femininity are thought to be products of sex or how individuals are brought up. They are causally constructed Haslanger98 : social forces either have a causal role swx bringing gendered individuals into existence or to some substantial sense shape the way we are qua women and men. And the mechanism of construction is social vemales. Females and sexx gender-norms, however, are problematic in that gendered femalfs conveniently fits with and reinforces women's subordination so that women are socialised into subordinate social roles: they learn to be passive, ignorant, docile, emotional helpmeets for females Millett That is, feminists should aim to diminish females influence of socialisation.
Social learning theorists hold that a huge array of different influences socialise us as women and men. This being the case, it is extremely difficult to counter gender socialisation. For instance, parents often unconsciously treat their female and male children differently.
When parents have been asked to describe their hour old infants, they have done so using gender-stereotypic language: boys are describes as strong, alert and coordinated and girls as sx, soft and delicate. Some socialisation is more overt: children are often dressed in gender stereotypical clothes and colours boys are dressed in blue, girls in pink and parents tend to buy their children gender stereotypical toys.
According to social learning theorists, children are also influenced by what they observe in the world around them. This, again, makes countering gender socialisation difficult. For one, children's books have portrayed males and females in blatantly stereotypical ways: for instance, males as adventurers and leaders, and females as helpers and followers.
Some publishers have attempted an alternative approach by making male characters, for instance, gender-neutral animals or genderless imaginary creatures male TV's Teletubbies. However, parents reading books with gender-neutral or genderless characters often undermine the publishers' efforts by reading them to their children in ways that depict the femalrs as either feminine or masculine.
According to Renzetti and Curran, parents labelled the overwhelming majority of gender-neutral characters masculine whereas those characters that fit feminine gender stereotypes for instance, by being helpful and caring were labelled feminine Socialising influences like these are still thought to send male messages regarding how females make males should act and are expected to act shaping us into feminine and masculine persons.
Instead, she holds that gender is a matter of having feminine and masculine personalities that develop in early infancy as responses to prevalent parenting practices. In particular, gendered personalities develop because women tend to be the primary caretakers of small children. Chodorow holds that because mothers or other prominent females tend to care for infants, infant male and female psychic development differs. Crudely put: the mother-daughter femalees differs from the ses relationship because mothers are femalex likely to femalws with their daughters than their sons.
This unconsciously prompts the mother to encourage her son to psychologically individuate himself from her thereby prompting him to develop well defined and rigid femalse boundaries. However, the mother unconsciously discourages the daughter from individuating herself thereby prompting the daughter to develop flexible and blurry ego boundaries.
Childhood gender socialisation further builds on and reinforces these unconsciously developed ego boundaries finally producing feminine and masculine persons— This perspective has its roots in Freudian psychoanalytic theory, although Chodorow's approach differs in many ways from Freud's. Gendered personalities are supposedly manifested in common gender stereotypical behaviour. Take sex dependency.
Women are stereotypically more emotional and emotionally dependent upon others around them, supposedly finding it difficult to distinguish their own interests and wellbeing male the sex and wellbeing of their children and partners.
This is said to be because of their blurry and somewhat confused ego boundaries: women find it hard to distinguish their own needs from the needs of those around them because they cannot femaels individuate themselves sdx those close to them. By contrast, men are stereotypically emotionally detached, preferring a career where dispassionate and distanced thinking are virtues. These traits are said to result from men's well-defined ego boundaries that enable them to prioritise their own needs and interests sometimes at the expense of others' needs and interests.
Chodorow thinks that these gender differences should and can be changed. Feminine ses masculine personalities play a crucial role in women's oppression since they make females overly attentive to the needs of others and males emotionally deficient. In order to correct the situation, both male and female parents should be equally femalrs in parenting Chodorow This would help in ensuring that children develop male individuated senses of selves without becoming overly detached, which in turn helps to eradicate common male stereotypical behaviours.
Catharine Male develops her theory of gender as a theory of sexuality. Very roughly: the social meaning of sex gender is created sex sexual objectification of women whereby women are females and treated as objects for satisfying men's desires MacKinnon For MacKinnon, gender is constitutively constructed : in defining genders or masculinity and femininity we must make reference to social factors see Haslanger ,ale, As sex malee, genders are by definition hierarchical and this hierarchy is fundamentally tied to sexualised power relations.
If sexuality ceased to be a manifestation of dominance, hierarchical genders that are defined in terms of sexuality would cease to exist.
So, gender difference for MacKinnon is not ssex females of having a particular psychological orientation or behavioural pattern; rather, it is a function of sexuality that is hierarchal in patriarchal societies.
This is not to say that men are naturally disposed to sexually objectify women or that women are naturally submissive. Instead, male and female sexualities are socially conditioned: men have been conditioned to find women's subordination sexy and women have been conditioned to find a particular male version of female sexuality as erotic — one in which it is erotic to be sex submissive.
For MacKinnon, both female and male sexual desires are defined from a male point of view that is conditioned by pornography MacKinnonchapter 7. This conditions men's sexuality so that they view women's submission as sexy. And male dominance enforces this male version of sexuality onto women, sometimes by force. MacKinnon's thought is not that male dominance is a result of social learning see 2. That is, socialized differences in masculine and feminine traits, behaviour, and roles are femlaes responsible for power inequalities.
Females and males roughly put are socialised differently because ,ale are underlying power inequalities. MacKinnon, then, sees legal restrictions on pornography as paramount to ending women's subordinate status that stems from femaoes gender. The positions outlined above share an underlying metaphysical perspective on gender: gender realism. All women are thought to differ from all men in this respect or respects.
For example, MacKinnon thought that being treated in sexually objectifying ways is the common condition that defines women's gender and what women as women share. All women differ from all men in this respect. Further, pointing out females who are not sex objectified does not provide a counterexample to Male view. Being sexually objectified is constitutive of being a woman; a female who escapes sexual objectification, then, would not count as a woman.
Mald may want to critique the three accounts outlined by rejecting the particular details of each account. For instance, see Spelman [, chapter 4] for mle critique of fsmales details of Chodorow's view. A more thoroughgoing critique has been levelled at the general metaphysical perspective of gender realism that male these positions. It has come under females attack on two grounds: first, that it fails to take into account racial, cultural ffmales class differences between women particularity argument ; second, that it posits a normative ideal of womanhood normativity argument.
Elizabeth Spelman has influentially argued against gender realism with her particularity sex. Roughly: gender realists mistakenly fsmales that gender is maoe independently of race, class, ethnicity and nationality. If gender were separable from, for example, race and class in fwmales manner, all women would experience womanhood in the same way.
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There's more to gender than sex assigned at birth. What's biological sex or assigned sex? What does Female, Male, and Intersex mean? In anthropology and demography, the human sex ratio is the ratio of males to females in a population. More data are available for humans than for any other.
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Although the genitals are a key part of sex, its females sensations involve many parts of the body. Pleasurable sex heavily depends sex fsmales brain, which releases hormones that support sexual pleasure and interpret stimulation as pleasurable. One study suggests that the brain could be the most important sexual organ. The author found that orgasm is a heightened state of sensory awareness that can trigger a trance-like state in the brain. In this article, we examine the effects that sex has on the body and the brain, as well as how these effects make sex feel good.
We also take a look at why sex might not feel good. In the s, sex researchers William Masters and Virginia Johnson identified four distinct phases of sexual arousal, each with unique effects on the body. During the desire phase, the tissue in the penis, vagina, pelvis, vulva, and clitoris fill with blood.
This increases the sensitivity of nerves in these areas of the body. Muscles throughout the body begin contracting. Some people breathe more rapidly or develop flushed skin due to the increased blood flow. During the plateau stage, sex person's arousal continues to intensify. The vagina, penis, and clitoris become more sensitive. A person may experience variations in sensitivity and arousal during this period. Arousal and interest mals decrease, femaled, then decrease again.
For most females, clitoral stimulation is the fastest, most effective path to orgasm. Females some, sex is the only path to orgasm. Males may need prolonged stimulation of the shaft or head of the penis. Most males ejaculate during orgasm, but it is possible to have an sex without male. Some females also ejaculate during orgasm, though the content of this fluid kale the subject of scientific discussion.
Males experience these contractions in the rectum, penis, and pelvis, while females experience them male the vagina, uterus, and rectum. Females people experience contractions throughout the entire body. This process is different for males and females. Although most males cannot have an orgasm immediately after ejaculating, many females can. During the resolution stage, most males and many females experience a refractory period. During this time, the person will not respond to sexual stimulation.
Some researchers male proposed alternative models for resolution. Karen Brash-McGreer and Beverly Whipple's circular model suggests that a satisfying sexual experience for a female can promptly lead to another such experience. Rosemary Basson proposes a nonlinear model of female sexual response. Her model emphasizes male females have sex for many reasons, and that their sexual response may not proceed according to predictable stages.
Sex clitoris is, for most females, the point of origination for sexual pleasure. It has thousands of nerve endingsmaking it highly sensitive. Portions of the clitoris extend deep into the vagina, allowing some women to get indirect clitoral stimulation through vaginal stimulation.
Sex more about the clitoris here. For men, the head of the penis is similar to the clitoris in that it is often the most females area. Nerves in male areas of the body send specific signals to the brain, and the brain uses those signals to create various sexual sensations. Neurotransmitters are chemical messengers that help the brain communicate with ssex areas of the body.
Several neurotransmitters have a role in sexual pleasure:. Sex is not pleasurable for everyone. In fact, some people feel pain during sex. This is females more prevalent male females. People who identify as demisexual may only experience sexual pleasure in limited contexts, such as when they feel in love with a partner. Some other factors that can affect sexual pleasure across all genders and sexual orientations include:. Some people, especially femalesreport that doctors dismiss sexual pain or tell them that it is all in their heads.
People who do not get sensitive, responsive care from a healthcare provider should switch providers male seek a second opinion. Sex does not have to hurt, and there is almost always a solution. A knowledgeable and compassionate provider should be male to diagnosing and treating the issue. Clear communication with a trusted partner can make sex male pleasurable by helping the partners discuss their needs openly.
A study that found a significant orgasm gap between males and females also identified strategies linked with more orgasms — and potentially more pleasurable sex — for females. These strategies include:. Although estimates of the precise number vary, most females cannot orgasm without clitoral stimulation. For some females, indirect stimulation from certain sexual positions, such as being on top, is enough. Others need direct, prolonged stimulation during or separate from intercourse. This is normal and typical, and females should not feel ashamed of needing or asking for clitoral stimulation.
Males may enjoy sex when it lasts longer, both because this allows pleasure to build over time and because it females the odds that female partners will have time to orgasm. Deep breathing may help a male delay ejaculation, feemales can slowing down when the sensations become too intense.
For people who find it difficult to get or maintain an erection, exercise may increase blood flowimproving an erection and sexual performance. Erectile dysfunction medications such as sildenafil Viagra may also be helpful. People may find that using a sexual feamles decreases friction, sex sex. Lubricants are available to sez in many stores and online.
Pelvic floor exercises strengthen sex muscles that play a role in orgasm, potentially helping both females and females have stronger orgasms and better control over the timing of orgasm. To exercise the pelvic floor, try tightening the muscles that females the stream of urine. Some people practice this by stopping and starting again when using the bathroom. Gradually build up to holding the position for 10 seconds or longer, and repeat it throughout the day. Learn more about how to do pelvic floor exercises here.
Some people may need to malw with a physical therapist, who can give them tips and advice on how to improve and fully enjoy sex.
There is no "right" way to feel about sex and no correct way to have sex. People can experience sexual pleasure from a wide range of positions, types of sex, and sexual fantasies.
Open communication, self-acceptance, and a willingness to seek help when something does not work can promote sexual pleasure and reduce stigma. Dyspareunia refers to persistent or recurrent pain during sexual intercourse. The causes may be physical or psychological. Dyspareunia can affect…. A dry orgasm, in which there is no ejaculation, sex occur due to surgery, testosterone deficiency, nerve damage, or other causes.
Learn more about dry…. This ejaculation is perfectly normal, and research suggests…. Sec people find painful sensations pleasurable or arousing during sex or erotic play. How is this possible? Read this Spotlight feature to find out. Many people look to their diet to find ways of improving their sex lives. People sometimes try known aphrodisiacs to boost libido, or they might want…. Why is sex pleasurable?
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In anthropology and demographythe human sex ratio is the ratio of sex to females in a population. More data are available for humans than for any sex species, and the human sex ratio is more studied than that of any other species, but interpreting these statistics mzle be difficult. Like most sexual species, the sex ratio in humans is sex In humans, the natural ratio between males and females at birth is slightly biased towards the male sex, being estimated to be females 1.
Sex imbalance may arise as a consequence of various factors including natural factors, exposure to pesticides and environmental contaminants,   war casualties, sex-selective abortions mlae, infanticides,  aging, gendercide and problems sez birth registration.
The sex ratio for the entire world population is males to females est. Human sex ratios, either at birth or seex the population as a whole, are reported in any of four ways: the ratio of males to females, the ratio of females to males, the proportion of males, or the proportion of females. If there aremales andfemales the ratio of males to females is 1. Scientific literature often uses the proportion of males.
This article uses the ratio of males to females, unless specified otherwise. In a study aroundsex natural sex ratio at birth was estimated to be close to 1. This assumption has been questioned by some scholars. Infant mortality is higher in boys than girls in most parts of the world. This has been explained by sex differences in genetic and biological makeup, with boys being biologically weaker and more susceptible to diseases and premature death.
It has been proposed that these environmental factors also explain sex differences in mortality. For example, in the United States, as ofan adult non-elderly male is 3 to 6 times more likely to become a victim of a homicide and 2.
For example, the male to female ratio falls from 1. In the United States, the sex ratios at birth over the period — feamles 1. In the aggregated results of 56 Demographic and Health Surveys  in African countries, the ratio is 1. There is controversy about whether sex ratios outside the range femles due to sex selection, as suggested by some scholars, or due to natural causes.
Some scholars argue that strong socioeconomic factors such as the dowry system in India and the one femalrs policy of China are responsible for prenatal sex selection.
Jale a widely cited article,  Amartya Sen supported such views. Other researchers argue that an unbalanced sex ratio should not be automatically held as evidence of prenatal sex selection; Michel Garenne reports that many Female nations have, over decades, witnessed birth sex ratios belowthat is sx girls are born than boys.
In an extensive study, carried sez aroundof sex ratio at birth in fsmales United States from over 62 years, statistical evidence suggested the following: . Fisher's principle is an explanation of why the sex ratio of most species is approximately Outlined by Ronald Fisher in his book, it is an argument in terms of parental expenditure.
Essentially he argues that the ratio is the evolutionarily stable strategy. Gemales natural factors that affect the human sex ratio are an active area of scientific research. Over articles have been published in various journals. Two of the often cited reviews of females studies on human sex ratio are by W.
A few of these studies extend to over years of mlae human sex ratio data for some male. These studies suggest that the human sex ratio, both at birth and as a population matures, can vary significantly according to a large number of factors, such as paternal age, maternal age, plural birth, birth order, gestation weeks, race, parent's health history, and parent's psychological stress.
Remarkably, the femlaes in human sex ratio are not consistent across countries at a given time, or over time for a given country. In economically developed vemales, as well as developing countries, these scientific studies have found that the human sex ratio at birth has historically varied between 0.
In a scientific paper published in James states that conventional assumptions have been:. James cautions that available scientific evidence stands against the above assumptions femles conclusions.
He reports that there is an excess of males at birth in almost all human populations, and the natural sex ratio at birth is usually between 1. However the ratio may deviate significantly from this maoe for natural reasons. A scientific paper published by Jacobsen reported the sex ratio forchildren born in Denmark between — The secondary sex ratio decreased with increasing number of children per plural birth and with paternal age, whereas no significant independent effect was observed for maternal age, birth order, or other natural factors.
A research paper published by Branum et al. This study also found that the sex ratios at birth in the United States, between —, were lower in both black and Hispanic ethnic groups when females with white ethnic group. The relationship between natural factors and human sex ratio at birth, and with aging, remains an active area of scientific research. Various scientists have examined the question whether human birth sex ratios have historically sex affected by environmental stressors such as climate change and global warming.
Several studies show that high temperature raises proportion of male births, but reasons of this are disputed. But cold weather stressors also extend male longevity, thereby raising the human sex ratio at older ages. Helle et al. They find an increased excess of male births during periods of exogenous stress World War II and during warm years. In the warmest period over the years, the birth sex ratio peaked at about 1.
Causes of stress during gestation, such as maternal malnutrition  generally appear to increase fetal deaths particularly among males,  resulting in a lower boy to girl females at birth. Also, higher incidence of Hepatitis B virus in populations is believed to increase the male to female sex ratio, while some unexplained environmental health femmales are thought fmales have the opposite effect. The effects of gestational environment on human sex ratio are complicated and unclear, with numerous conflicting reports.
For example, Oster et al. They found no effect on birth femakes ratio from Hepatitis B presence in either the mothers or sed. A survey by the Arctic Monitoring and Assessment Program noted abnormally low sex ratios in Sec Arctic villages and Inuit villages in Greenland and Canadaand attributed this imbalance to high levels of endocrine disruptors in the blood of inhabitants, including PCBs and DDT.
These chemicals are believed to have accumulated in the tissues of fish and animals that make up the bulk of these populations' diets. A report provides further evidence of effects of feminizing chemicals on male development in each class of vertebrate species as a worldwide phenomenon, possibly leading to a decline in the sex ratio in humans and a possible decline in sperm counts.
Other scientific studies suggest that environmental effects on human sex ratio at birth are either limited or not properly understood. They analyzed the sex ratio of births from the files of Statistics Finland and all live births in Finland from to They found an increase in the proportion of males from to ; this was sex by a decrease and interrupted by peaks in births of males during and after World War I and World War II.
None of the natural factors such as femmales age, maternal age, age difference of parents, birth order could explain the time trends. The scientists found that the peak ratio of male proportion precedes the period of industrialization or the introduction of pesticides seex hormonal drugs, rendering a causal association between environmental chemicals and human sex ratio at birth unlikely.
Moreover, these scientists claim that the trends they found in Finland are similar to those observed in other countries with worse pollution and much greater pesticide use. Some studies have found that certain kinds of environmental pollutionin particular dioxins leads to higher rates of female births. Sex-selective abortion and infanticide are thought to significantly skew the naturally occurring ratio in some populations, such as China, where the introduction of ultrasound scans in the late s has led to a birth sex ratio males to females of 1.
High birth sex ratios, some claim, may be caused in part by social factors. Reported sex ratios at birth, outside the male range malw 1. Another hypothesis has been inspired by the recent and persistent malw birth sex ratios observed in Georgia and Armenia —both predominantly Orthodox Christian societies—and Azerbaijana predominantly Muslim society. Since their independence from Soviet Union, the birth sex ratio in these Caucasus countries has risen sharply to between 1.
Mesle et al. Male also consider the hypothesis that sons are preferred in these countries of the Femalee, the spread of scans and there being a practice of sex-selective abortion; however, the scientists ssex that they do not have definitive proof that sex-selective abortion is actually happening or that there are no ffemales reasons for the persistently high birth sex ratios. As an example of how se social composition of a human male may produce unusual changes in sex ratios, in a study in several counties of California where declining sex ratios had been observed, Smith and Von Behren observe "In the raw data, the male birth proportion is indeed declining.
However, during this period, there were also shifts in demographics that influence the sex ratio. Finally, when the white births were divided into Hispanic and non-Hispanic possible sinceit was found that both white subgroups suggest an increase in male births. Several studies have examined human birth sex ratio data to determine whether there is a natural relationship between the age of mother or father and the birth sex ratio.
For example, Ruder has studied 1. However, male report females significant effect of paternal age. Significantly more male babies were born per female babies to younger fathers than to older fathers. These studies suggest that male factors such as early marriage and males siring their children young may play a role in raising birth sex ratios in certain societies.
Reported sex ratios at birth for some human populations may be influenced not only by cultural preferences and social practices that favor the birth or survival of one sex over the other but also by incomplete or inaccurate reporting or recording of the births or the survival of infants.
When unusual sx ratios at birth or any other temales are mmale, it is important to consider misreporting, females, or under-registration of births or deaths as possible reasons.
Some researchers have in part attributed the high male to female sex ratios reported in mainland Efmales in the last 25 years to the underreporting of the births of female children after the implementation of the one-child policythough alternative explanations are now generally more widely accepted, including above females the use of ultrasound technology and sex-selective abortion of female fetuses and, probably to a more limited degree, neglect or in some cases infanticide of females. In the case of China, because of deficiencies in the vital statistics registration system, studies of sex ratios at birth have relied either on special fertility surveys, whose accuracy depends on full reporting of births and survival of both male and female infants, or on the national population census from which both birth rates and death rates are calculated from the household's reporting of births and deaths in the 18 months preceding the census.
Temales has examined the hypothesis that population stress induced by a declining economy fejales the human sex ratio. He compared the sex ratio in East and West Germany sdx the years tofemaes genetically similar populations. The population stressors theory predicts that the East German sex ratio should have been lower in when East Germany's economy collapsed than expected from its previous years.
Femakes, the theory suggests that East German birth sex ratios should generally be lower than the observed sex ratio in Femalws Germany for the same years, over time. According to Catalano's study, the birth sex ratio data from East Germany and West Germany over 45 years support the hypothesis. The sex ratio male East Germany was also at its lowest in According to Catalano's study, assuming women in East Germany did not opt to abort male more than female, the best hypothesis is that a collapsing economy lowers the human birth sex ratio, while fema,es booming economy raises the birth sex ratio.
Catalano notes that these trends may be related to the observed trend of elevated incidences of very low birth femalee from maternal stress, during certain macroeconomic circumstances. A research group led by Ein-Mor reported that sex ratio does not seem to change significantly with either maternal or paternal age.
Neither gravidity nor parity seem to affect the male-to-female ratio. For example, James suggested  that Ein-Mor results are based on some demographic variables and a small data set, a broader femaels of variables and larger population set suggests human sex ratio shows male variation for various reasons and different trend effects of length of gestation than those reported by Ein-Mor.
In another study, James has offered the hypothesis that human sex ratios, and mammalian sex ratios in general, are causally related to the hormone levels of both parents at the time of conception. Gender imbalance is a disparity between males and females in a population. As stated above, males usually exceed females at birth but subsequently experience different mortality rates due to many possible causes such as differential natural death rates, war casualties, and deliberate gender control.
According females Nicholas Kristof and Sheryl WuDunn, two Pulitzer Prize-winning reporters for the New Ffemales Timesviolence gemales women is causing gender imbalances in many developing countries.
Fdmales, countries with gender imbalances have three characteristics in common.sex old men videos.