Why absence of human penis bone?

I found little information about penis bone on internet. The baculum (also penis bone, penile bone or os penis) is a bone found in the penis of most placental mammals. It is absent in humans, but present in other primates, such as the gorilla and chimpanzee. The bone aids sexual intercourse by maintaining sufficient stiffness during sexual penetration. The female equivalent is the os clitoridis – a bone in the clitoris. Mammals having a penile bone (in males) and a clitoral bone (in females) include various eutherians. Key words: female mammals also have a bone in clitoral shaft.

Unlike other primates, humans lack an os penis or os clitoris; however, this bone is much reduced among the great apes: in many ape species it is a relatively insignificant 10–20 mm structure. Such a wide distribution among placental mammals suggests that the bone evolved early in the history of these mammals, and was subsequently lost in certain groups. There are two main theories about absence of human penis bone. 

One theory is, it has long been believed, that humans evolved smooth penises as a result of adopting a more monogamous reproductive strategy than their early human ancestors. Those ancestors may have used penile spines to remove the sperm of competitors when they mated with females. However, exactly how this change came about is not known.

I don’t agree with this view at all. The reason is very simple: Monogamy is definitely a product of modern civilization, but the absence of penis bone maybe happened in millions of years ago, I really do not believe that our human ancestors, at the beginning, are monogamous. Here I emphasize my view about monogamy again that the reason of emergence of monogamy is not because of human rights or love, and it is totally a result of interests’ compromise between males. Love is just a emotion between two equal and independent person, no materials money or survival dependencies. Woman starting went out of the kitchen and began to make money is because of the First World War, so I think love is absolutely a modern vocabulary. Women, as a vulnerable group, choose a marriage only for survival before really economic independence. Even if love really exists long time ago, it must be a luxury, belonged to the wealthy aristocracy. Until now, in some areas, women still a male appendage, and they can’t choose their marriage, they can’t go to school like boys, they can’t even take off the fucking veil. What is love? Bullshit. In old China, the girls can’t even meet the husbands before the night they get married. Now, the more highly education women got, the more they choose to be celibacy. It is definitely a progress of women self-awareness that they start the pursuit of the spiritual world, after the satisfaction of the material world, not only reproduction, but it is just a good start, still far from completely self-consciousness.

The other theory is that the loss of the bone in humans, when it is present in our nearest related species the chimpanzee, is because humans "evolved a mating system in which the male tended to accompany a particular female all the time to try to ensure paternity of her children" which allows for frequent matings of short duration. Observation suggests that primates with a baculum only infrequently encounter females, but engage in longer periods of copulation that the baculum makes possible, thereby maximizing their chances of fathering the female's offspring. Human females exhibit concealed ovulation also known as 'hidden estrus', meaning it is almost impossible to tell when the female is fertile, so frequent matings would be necessary to ensure paternity.

I don’t fully agree with this explanation. First I admit the truth of concealed ovulation in female human, maybe that triggered frequent matings would be necessary to ensure female to be pregnant, but there is no relationship between frequent matings and the absence of human penis bone. Conversely, I do believe that the existence of penis bone is helpful for mating. Because the penis has a very simple job to do: to maintain sufficient stiffness to enter an orifice during the mating, and to deliver sperm. The baculum is generally kept in the male's abdomen until it is required, at which point abdominal muscles push it out into the penis, thus causing an erection. The function of penis bone is to help males maintain an erection long enough to penetrate a female's reproductive tract and deliver sperm. You can imagine that, when a female in ovulation period, but the male is not the mood to mate and can’t get his penis hard, and the result is he can’t even complete the insertion. What if he still has penis bone? He can insert anyway, so I think the presence of the penis bone is very conducive to mating. I do believe there is no word “Impotence”, if the penis bone still on human.

So, inevitably, this brings us to the question of why humans are the only apes to lack a penis bone. I don’t agree with the two explanations of absence of penis bone, and we have to find the answers in some different views. 

1, From the view of mating season and mating purposes
Undoubtedly, all the animals have specific mating season, except human. Here mating season means the seasonal period when a female animal's estrous cycle is active, signaling animals to mate. Only during the female estrus, they exhibit a sexually receptive behavior, a situation that may be signaled by visible physiologic changes. A signal trait of estrus is the lordosis reflex, in which the animal spontaneously elevates her hindquarters. What about our human? Key words: Only during the female estrus, they exhibit a sexually receptive behavior. Apparently, our human can mate at any time all around the year. Why other animals only mate in female estrous period, except our human?

The authoritative view is given for that: the mating season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding, and humans have evolved not to need one and many animals do have a mating season because their food resources or the temperature where they live changes throughout the year, so the there's no real need for a mating season for humans. I think this explanation is very classical, but I want to dig some deeper factors: the mating purposes. 

I do believe that the mating purpose during mostly non-human animals is for reproduction, but what about our human? What is the purpose of human mating? Why do male human need to mate also during female non-ovulation period? Why do women still have to be “receptacle”, even after her menopause? Why female human have to accept the sexual behavior during non-ovulation period? I really do have many questions, but I think my questions are not hard to explain. Come on, poor women; please do not forget what Freud said “the vagina has value only as a receptacle for penis.”

Besides this classical theory, I have my story to say. Purpose determines the action; conversely, different actions are due to different purposes. Apparently, mating purpose during animals is only for reproduction, so they choose the strategy that only mating in most suitable season and female ovulation period. During human race, sex is so much more than a means of reproduction. What is our purpose of mating? Fun, pleasure and relax. Here I want to emphasize that the fun, pleasure and relax I mean is for self, not for others. I agree with the Adam Smith’s statement about the relationship between Egoism and Altruism. He writes in his Wealth of Nations: “It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantages.” Here I use the same logic to say, in the game of sex, every orgasm is a result of masturbation, no one can give you an orgasm, but yourself, and every one only have the ability for self-masturbation, but no other-masturbation.

Here I want to ask the followers of G-spot some questions: do you believe female mammals also have G-spot? Because all female mammals share the same reproductive system, ovary, uterus and vagina so on, according to G-spot theory, non-human female mammals also deserve to get orgasm from male penetration. Maybe you should believe that female animals were fucked to get multiple orgasms, because they always have crazy mating so many times during mating season. Next question: why they exhibit a sexually receptive behavior only during female estrus? Why do they refuse to experience the amazing multiple orgasms in non-estrus period? Maybe they are stupid, yeah?

2, From the different ways of sex

Traditional intercourse:
At the time of penetration, the canine penis is not erect, and only able to penetrate the female because it includes a narrow bone called the "baculum ", a feature of most placental mammals. The baculum is kept in the abdomen and, when needed, a set of muscles push it into a sheath in the fleshy part of the penis. It enters within the erectile tissue, providing rigidness to aid during the copulation. Unlike human sexual intercourse , where the male penis commonly becomes erect before entering the female, canine copulation involves the male first penetrating the female, after which swelling of the penis to erection occurs, which usually happens rapidly.
Briefly speaking, because of absence of penis bone, male human need to get penis hard first, then penetrate into woman’s body; for other male mammals with baculum, they penetrate into female body using penis bone first, and then penis get erection because of rub. I do believe that whether penis gets erect or not before insert is the key in human sex evolution. What does this mean? What exactly makes penis of male human get hard before any touch of it. Let me give you further details.

Masturbation is the sexual stimulation of one's own genitals, usually to the point of orgasm. The stimulation can be performed using the hands, fingers, everyday objects, or dedicated sex toys. Key words: usually to the point of orgasm. In childhood the male and female bodies are very similar, both without masturbation. Masturbation is quite common among young adolescent males, since the development of male secondary sexual characteristics, but few women can get real orgasm through masturbation after female secondary sexual characteristics. I do think that is the key why female suffer sexual dysfunction, because men do have a good start in this subject, but women lag behind at the beginning. Why is that? 

Animal masturbation has been observed in many species, according to some news, but I am not going to believe them all. Some news said birds can masturbate, that is not possible at all, because birds don’t even have penis, and they reproduce by cloaca kiss. I do believe masturbation is not so popular in the animal kingdom. If animals really have self-pleasuring behavior, as the stronger side, male must choose the strategy of rape to increase the enjoyment, whatever in female estrus period or not, but mostly of male animals still choose to mate only during female ovulation period. Please don’t tell me they respect female rights, so they choose masturbation, not rape. I am kidding. Let’s go back to the key words of masturbation: usually to the point of orgasm. I think we should differentiate so-called animals’ masturbation from human masturbation on this point. If the purpose of masturbation during animals is for ejaculation as same as male human, we can say that male animals really have masturbation; if the purpose is not for ejaculation, I do agree with this view that masturbation during animals may help to keep the genitals clean and stave off sexually-transmitted infections. We have lot of things unknown.

Homosexual behavior in animals:
Research indicates that various forms of same-sex sexual behavior are found throughout the animal kingdom. Homosexual behaviour has been observed in 1,500 animal species. The most well-known homosexual animal is the dwarf chimpanzee, one of humanity's closes relatives, and the entire species is bisexual. Homosexuality is also quite common among dolphins and killer whales and the pairing of males and females is fleeting, while between males, a pair can stay together for years. Homosexual behavior in animals is often performed in non-reproductive ways, using snout, flippers and genital rubbing, without regard to gender.

The following picture is two female domestic dogs engaging in sex play. 

What are they doing? Apparently, she can’t penetrate her clitoris into the other’s vagina. I guess she just rub her clitoris shaft against the other’s body for pleasure. Does she really enjoy the climax shiver like males? I really don’t know. If female mammals really can get the climax shiver through rubbing the clitoris shaft, female human was totally a joke.

Why homosexual behavior in animals is so common, even in birds, as you know, birds don’t even have penis at all, they can’t have the climax shiver through anyway. Birds that mate using this method touch their cloacae together, in some species for only a few seconds, sufficient time for sperm to be transferred from the male to the female. Why homosexual behavior happened if we think sex in animals is only for reproduction? For pleasure, fun or showing intimacy or ensuring loyalty or connection or strengthening the bonds for the group.

Let’s go back to the question that what exactly makes penis of male human get hard before any touch of it. Everyone knows that men always like to see porn, whenever in masturbation or in making love with someone. Why is that? I think because seeing porn can evoke men’s lust and penis can get erect as a physiological response. Obviously, men can not only rely on direct penis stimulation to get an erection, but also on the brain's sexual fantasies to get hard. It is undeniable sexual fantasies take very important role in human sex. Sometimes a man was hit by a bad thing, and he can’t get penis hard, whatever how hard you touch him. 

But in animals, the porn doesn’t work any more. For example, in a zoo, in order to breed more offspring during rare species, the staff played porn film in front of the animals, but unfortunately, non-human male mammals don’t become a sex machine after seeing porn like men. Compared to our human erotic intercourse, animals’ mating is very pure. 

Same action, but with different motives. It is not hard to understand, and I can give you another same logical example here: nipple sucking. I think you don’t feel any lust, when you saw a baby sucking a woman’s nipple, because the fact is the baby really doesn’t have any lust in the brain when sucking. What about a man? You have a very different feeling, when you see a man suck woman’s nipple, right? Because it is full of porn. Intercourse shares the same logic. What exactly makes so different between male human and male non-human mammals in sex? I think the key problem is the brain. In human, the reflex arc of sex includes the brain, but in the non-human animals, the reflex arc of sex only includes low central nervous spinal cord. That is why male can get erection when seeing porn, but other animals can’t. 

Wet dream:

A nocturnal emission or wet dream is a type of spontaneous orgasm, involving either erection 
and/or ejaculation during sleep for a male, or lubrication of the vagina for a female. Nocturnal 
emissions are most common during adolescence and early young adult years, but they may 
happen any time after puberty. It is possible to wake up during a wet dream, or to simply sleep
through it. There are numerous cultural and religious views on nocturnal emissions, such as 
caused by a succubus copulating so on and so forth. 

In short, I think the wet dream is due to the subconscious desire for sex. This subconscious must come from the brain, and I guess non-human mammals don’t have nocturnal emission, maybe animals don’t even have dream.

3, Main product and by-product: vasectomy
Vasectomy prevents sperm from mixing with semen by blocking the sperm ducts. After vasectomy, sperm continue to be produced. However, during ejaculation, the sperm make it only as far as the newly blocked point in the ducts, where they are reabsorbed. As a result, there are no sperm in the ejaculated semen during intercourse.

At the beginning, a lot of men are concerned about what changes in their sex life after the procedure. The short answer is that there is no adverse change in the quality of sexual enjoyment for either partner after a vasectomy. In fact, many people report improvements in sexual enjoyment because they no longer need to worry about an unwanted pregnancy. Orgasm, the pleasure we receive during climax is a physiological process that occurs in the brain is unaffected by the vasectomy nor is it related to the presence of sperm in the ejaculate. Sperm in the ejaculate has no relationship to the quality of your sexual intercourse or the satisfaction during intercourse you or your partner would have after a vasectomy. The only purpose of sperm in the ejaculate is to procreate. 
The key words: orgasm is a physiological process that occurs in the brain. Apparently, we can conclude that the orgasm, in human experience, is a bottom-up process, and in this process of nerve conduction, the main product is the pleasure in brain, and the by-product is discharge of sperm.

4, Refractory period:
As we all know, the male human has a refractory period after orgasm. What is refractory period exactly? Wikipedia gives the definition like that: in human sexuality, the refractory period is usually the recovery phase after orgasm during which it is physiologically impossible for a man to have additional orgasms. It varies widely among individuals, ranging from minutes to days. According to some researches, the post-orgasmic refractory period also occurs in other male animals. About the mechanism of refractory period, basically, the release of some special hormone, like prolactin and hormone oxytocin, are thought to be largely responsible for the post-orgasmic refractory period seen in men, and the amount by which oxytocin is increased may affect the length of each refractory period, and prolactin is considered to represses dopamine, which is responsible for sexual arousal. 

Frankly speaking, I don’t know the function of prolactin, oxytocin or dopamine exactly, but I noticed that refractory period must relate to some release of pituitary gland or brain. Though it is generally reported that women do not experience a refractory period and thus can experience an additional orgasm, or multiple orgasms, soon after the first, some sources state that both men and women experience a refractory period because women may also experience a period after orgasm in which further sexual stimulation does not produce excitement. Here I don’t want to tell you how stupid the idea of female multiple orgasms, and multiple orgasms mean no orgasm at all, but I want to go to another subject: do other non-human male mammals also have the post-orgasmic refractory period? 

Refractory period in male animals are very vague, including our closest relatives chimpanzees. Here I think lion’ mating is a classical example. Lions like most animals only mate during mating season. During a mating bout, a couple may copulate twenty to forty times a day for several days. Some lions mate over 50 times a day, but mostly of mating only last 10 seconds or less. Once the female has cubs, she will not mate again. Zoologists have not found significant refractory period in lions. I think it is not hard to understand, because refractory period must inevitably lead to drowsiness, if male lions have refractory period like men, they can’t accomplish the tough task like 50 times a day. In general, I don’t believe non-human mammals have refractory period after ejaculation, notice I use the word “ejaculation” here, not “orgasm”, because the refractory period is the result of the brain triggered, it come after orgasm, not ejaculation. Maybe that is why some males claim that sometimes they can ejaculate, but no orgasm. I think whether ejaculation or shiver is controlled by spine, but whether orgasm pleasure is controlled by brain. I will try to describe the details in future.
5, Key words: female mammals also have a bone in clitoral shaft.
I am curious that we can understand the meaning of existence of penis bone, if we consider the purpose to help the male to insert, why female mammals still have clitoris bone? Apparently, it has nothing to do. This question is as same as the function of clitoris shaft, it is useless, but female still have it. I think it is related to the genes on X chromosome. So far, most of mammals don’t lose the bone’s genes yet, but our human have lost it already.
Continue to ask, what is the premise of losing the genes? Of course it is not to affect animals’ survival and reproduction. In other words, those animals, who can get penis hard before insert, give the opportunity for the genes’ missing.
All in all, I do believe the evolution of the brain and nerves is the key to distinguish human from animals. We have to figure out something like orgasm is orgasm, ejaculation is ejaculation, and orgasm pleasure comes from higher central nervous system: Brain, and ejaculation reflex is controlled by lower central nervous system: Spine. We really have to redefine lots of things. I believe the evolution of human sex reflex arc from spine to brain is due to the rapid expansion of brain and nerves during X chromosome or autosomes, Y chromosome has nothing to do that. Ironically, after neural pathway established, Y used it much better than X. There are lots of things unknown, our human beings are still ignorant in many areas.


Is that karma?


1,         我顿时想起了老江在接受CNN记者华莱士采访时被问到中国为什么不实行民主选举时回答说“中国人素质太差,不适合民主选举”。我不得不佩服老江同志的敏锐洞察力看穿了中国人的本质,都是这种货色的SB,中国目前的确不适合民主选举。最后的结果中共倒台了,但是也没有迎接到普选,一个王朝倒下去,另一个山大王站出来,改朝换代而已。我现在倒不希望中共那么快死了,如果它一旦死了,这些十多亿如此是非颠倒,黑白不明的中国人到底该咋办呢?

2,            Dawkins给出的解释为什么生物体要参与“瓶颈”般的生命循环,将一个螺旋桨发动机如何改成喷气式发动机呢?你做不到,你必须抛弃螺旋桨风发动机,回到绘图板上重新来。有些人一辈子都是不可能清醒的,他唯一能做的只有死亡,历史的车轮会无情的压过她的尸体前进。我但愿她的女儿不像她一般愚蠢至极,思想上的进化太难了,赶紧死吧。

3,              我原谅sharon stone 说的Karma的言论了,because she is right.这样的人死的越多越早,中国进化的越快。她要活到80岁,哪给影响多少人啊?就像朝鲜人民广场上誓死保卫金正恩的SB一样,他要死,就让他们死好了。


亲爱的美美们,加油吧,向官二代红二代进攻吧,繁殖出三代来,这没有什么可耻的,反正你被谁干都是干,为什么不挑一个性价比高的呢??她的丫头以后痛苦的日子还在后面的。上学送礼,学业压力,就业男女歧视,等着吧,好日子等着她呢。By the way,我是不会把我的基因撒播在这片罪恶的土壤上。


What are the genders?

I saw the news, according to Reuters - Several hundred thousand opponents of same-sex marriage marched in central Paris on Sunday. I did not expect that the French people who are so romantic nation actually value the genders so much. The Nation, who owns the Charles de Gaulle the greatest man in human history, loses the past glory immediately in my heart. It reminds me that the vast majority of people are always stupid in human history, whatever in west or east. So today, I want to have a look at how we define the female and male, and what exactly control the sex determination. 

All living things reproduce. Reproduction is the process of generating offspring. There are only two types of reproduction: sexual and asexual, whatever animals or plants. Here I am not going to see the differences, advantages or disadvantages of sexual and asexual reproduction, and this chapter only focuses on how sex determination. 

1Apparently, higher organisms have resorted to sexual reproduction in spite of its complexity, although sexual reproduction involves more time and energy.   Most animals and some plants have two genders, and sex-determining mechanism in different types of organisms is a big difference. How is gender determined in an organism? It is actually determined in different ways. It is broadly divided into two main categories: temperature-dependent sex determination (TSD) and genotypic sex determination (GSD).

TSD: Precisely speaking, the temperature-dependent sex determination is just one of the non-genetic sex-determinations. Many other sex-determination systems exist. In some species of reptiles, including alligators, some turtles, the tuatara, sex is determined by the temperature at which the egg is incubated during a temperature sensitive period. The temperatures required for the specific sexes are known as the female promoting temperature and the male promoting temperature. When the temperature stays near the threshold during the temperature sensitive period, the sex ratio is varied between the two sexes. For example, in sea turtles, warmer temperatures produce more or all females, cool temperatures produce more or all males, and the pivotal temperature is the constant incubation temperature that produces equal numbers of males and females. TSD also occurs in other reptiles (crocodilians, some freshwater and land turtles, some lizards), some types of fish, some types of invertebrates, etc.
In TSD animals, how do we define the genders? Apparently, the only way we define it is depending on sex expressive traits, because the same genders may not share the same sexual genes.
GSD: Genotypic sex determination occurs when sex is established by genetic factors (e.g. sex chromosomes) at conception and it has two main types: XX/XY and ZW/ZZ. The XX/XY sex-determination system is the most familiar, as it is found in humans. In the system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY). The XY sex chromosomes are different in shape and size from each other, unlike the autosomes. Some species (including humans) have a gene SRY on the Y chromosome that determines maleness. The ZW sex-determination system is found in birds, reptiles, some insects and other organisms. The ZW sex-determination system is reversed compared to the XY system: females have two different kinds of chromosomes (ZW), and males have two of the same kind of chromosomes (ZZ). In the chicken, this was found to be dependent on the expression of DMRT1. In birds, the genes FET1 and ASW are found on the W chromosome for females, similar to how the Y chromosome contains SRY. However, not all species depend upon the W for their sex. Because the use of ZW sex determination is varied, it is still unknown how exactly most species determine their sex. I roughly agree that God always finds a way, when he determines to do something.

In XX/XY system, Y chromosome evolved from X chromosome, in contrary in WZ/ZZ system, W evolved from Z chromosome. In the history of long evolution, some genes on Y and W chromosomes have been partially degradedso Y or W chromosome can’t synthesize the normal sex organ independently.

In GSD animals, how do we define the genders? If you think the one who has penis is a male, what about the birds with WZ chromosomes and fish? There is no big difference between two sexes, because neither sex has penis. Birds choose cloaca kiss to fertilize, and fish basically are in vitro fertilization. Even in mammals, you can not easily define genders.
2Next, we are going to see some special examples in mammals which people call as abnormality.


A freemartin or free-martin is an infertile female mammal which has masculinized behavior and non-functioning ovaries. It is genetically female, but has many characteristics of a male. The ovaries of the freemartin do not develop correctly, and they remain very small. Also, the ovaries of a freemartin do not produce the hormones necessary to induce the behavioral signs of heat. The external vulvar region can range from a very normal looking female to a female that appears to be male. Usually, the vulva is normal except that in some animals an enlarged clitoris and large tufts of vulvar hair exist. In short, these animals often have a masculine steer-like appearance, but with XX chromosomes.

The cause of this disease is, in most cattle twins, the blood vessels in the chorions become interconnected, allowing blood from each twin to flow around the other. If a fetus has XX chromosomes, the lack of testosterone production during gestation will allow her to develop female external and internal genitalia. Male animals develop differently in the womb because their XY chromosomal arrangement causes them to produce testosterone. This hormone inhibits female reproductive tract development. When mixed sex twins are developing, it is possible for the blood vessels within the two placentas so fuse and form a common circulation. When this happens, the testosterone produced by the male calf is able to circulate to the female twin and affect her sexual differentiation. If both fetuses are the same sex this is of no significance, but if they are different, male hormones pass from the male twin to the female twin. It also occurs occasionally in other mammals including sheep, goats and pigs.

The key word: the twins shared the same placenta and the female one was affected by the testosterone from the male one. I guess if a fertilized egg was injected by outside testosterone from the beginning, the female babies always have masculine vulva. In other words, if male really has a uterus, is he appropriate to have a baby? I do think scientists also can create artificial freemartin human. You could say I have a daydream, but I have another perfect evidence to support my daydream - Spotted Hyena.
Spotted Hyena

The female Spotted Hyena's urogenital system is unique among mammals: there is no vagina, and the clitoris is as large and as erectile as the male's penis - only the shape of the glans makes it possible to tell the sexes apart. In the case of female spotted hyena, the vulva is fused, and the clitoris is used for urination, mating (when the clitoris contracts, while the opening widens to allow penetration) and giving birth. When spotted hyaenas mate, the male inserts his erect phallus into the female's flaccid one. Another curious fact about female spotted hyenas, which scientists have confirmed, is that they carry higher levels of testosterone than the males in their blood, and this is something that can be observed as early as the embryo stage. That's why biologists initially believed that the development of the clitoris was caused by the huge quantities of testosterone to be found in the fetus.

The key words: female spotted hyenas have higher levels of testosterone than the males and the baby girl who lived in the mother’s body like this must inevitably be led to masculine vulva. This point can be understandable. In long history of spotted hyena evolution, she has already known how to get along with that external factor in peace and evolved a special reproductive system under that. I think we can do an experiment like this: have an artificial insemination spotted hyena, and then put this zygote into normal dog’s uterus, and see what the female baby dog’s vulva looks like? We will know whether it is affected by mother or not? I bet the little female dog is goint to have a normal feminine vulva, but infertility. The influence from mother to child or between the twins is not just limited to the sex hormone, and they also can exchange the cells.

Here I don’t want to talk about "chimera" in Greek mythology where it means a monster: part goat, part lion, part snake. In human biology, a chimera is an organism with at least two genetically distinct types of cells -- or, in other words, someone meant to be a twin. But while in the mother's womb, two fertilized eggs fuse, becoming one fetus that carries two distinct genetic codes -- two separate strands of DNA. 

So far the case of Lydia Fairchild is the most famous case in U.S., and it turned out she's a chimera which is a fusion of non-identical twins, and the best thing of this case is to make lots of researchers started to pay attention to chimera on human. Here I have another big question: where are the non-identical twins from? Apparently, chimera must be a fusion of non-identical twins, and there is no cells exchange problem in identical twins, because no matter they exchange the cells or not, they always share the same genes, and you can’t find out. What about fraternal twins? But fraternal twins each have their own placenta and own amniotic sac, two different placenta means they both directly exchange everything with the mother, and two different amniotic sac means they don’t have any chance to exchange anything to each other. I think the fraternal twins are very hard to fuse together, so we can easily find that those conjoined twins are identical twins, at least so far we don’t find any conjoined twins are from traditional fraternal yet, and I also think the fraternal twins are very hard to affect each other, otherwise we must can find lots of fraternal female twin’s vulva masculinization, due to her brother’s androgens.

In the uterus, a majority of monozygotic twins (60–70%) share the same placenta but have separate amniotic sacs. In 18–30% of monozygotic twins each fetus has a separate placenta and a separate amniotic sac. A small number (1–2%) of monozygotic twins share the same placenta and amniotic sac. Fraternal twins each have their own placenta and own amniotic sac.

Microchimerism (abbreviated Mc) is the presence of a small number of cells that originate from another individual and are therefore genetically distinct from the cells of the host individual. Microchimerism in humans commonly happens during pregnancy. Cells from the fetus' immune system can enter the mother through the placenta, where they may survive and continue to reproduce through mitosis. In some cases, the descendants of these fetal cells remain in the mother decades later. The same process in reverse can result in populations of maternal immune cells living in the fetus, though this is less common. I think as time goes by, microchimerism will be observed in many tissues and organs in our human. Here I want to illustrate that freemartin doesn’t mean she is a microchimerism, maybe her vulva development is just interfered by androgens from her brother, but she is not a chimera at all. I just make a guess, what I want to say is they are not necessary and sufficient conditions. Same logic to Spotted Hyena. I want to emphasize that If the Microchimerism between mother and child really happens generally, I think we should reconsider the surrogacy very carefully.

No matter what type of the twins, they always have to exchange things with the mother, so we can understand the chimera between child and mother, but what about the chimera between the twins? I think we have to know another Interesting case – polar twins.

Semi-identical twins

According to BBC news, Scientists have revealed details of the world's only known case of "semi-identical" twins. Researchers have discovered a pair of twins who are identical through their mother's side, but share only half their genes on their father's side. 

Researchers investigated the twins' genetic makeup because one was born with ambiguous genitalia. This twin turned out to be a 'true hermaphrodite', with both ovarian and testicular tissue. The other twin is anatomically male. Genetic tests revealed that each twin contained some 'female' cells with two X chromosomes, and some 'male' cells with an X and a Y. The proportion of each type varies from tissue to tissue in each twin, the researchers report in Human Genetics. So scientists gave the explanation is that the 'semi-identical' twins are the result of two sperm cells fusing with a single egg — a previously unreported way for twins to come about, say the team that made the finding.

Frankly speaking, I do not agree with the interpretation like that. The explanation they gave depends on two evidences: one is the twins both are chimaeras, and the other is one of the twins was born with ambiguous genitalia and turned out to be a 'true hermaphrodite' with both ovarian and testicular tissue. I think these two points are insufficient to support the conclusion they gave. Here I can give you another story depending on these two points.

We have to recall Meiosis first. In humans (and most vertebrates), the first polar body does not go on to meiosis II, but the secondary oocyte does proceed as far as metaphase of meiosis II and then stops. Only if fertilization occurs will meiosis II ever be completed. Entry of the sperm restarts the cell cycle. In principle, polar bodies are fertilized by sperm, even if the egg cell and a polar body were both fertilized by separate sperms., further development would usually not occur because the zygote formed by the fusion of the sperm and polar body would not have enough cytoplasm or stored nutrients to feed the developing embryo. The following figure is a normal process of meiosis and fertilization:

One egg × One sperm

I don’t know what the key it is to decide which lucky half can win all cytoplasm and which poor half genes have to dies due to uneven splitting of the cytoplasm, but I believe competition is everywhere. Once the game is evenly matched, the first polar body also gets some cytoplasm as much as secondary oocyte. The following figure is an even splitting during meiosis I, but uneven splitting during meiosis II. Due to the two sperm are random, so they share 50% identical genes to each other. Don’t forget homologous chromosomes segregate from each other during meiosis I, so the two eggs share 0% identical genes. The result is the twins share no genes on their mother's side, but only half their genes on their father's side. Maybe we can call them “Quarter identical twins”.

Two eggs(share 0% identical genes) × Two sperm(share 50% identical genes)

The following figure is an uneven splitting during meiosis I, but even splitting during meiosis II. Due to what happened is just sister chromatids are separated during meiosis II, and the two sperm are still random, so the result is the twins share the exactly same genes on their mother's side, but only half their genes on their father's side. Maybe we can call them “Three quarters identical twins”. Since it is very difficult to separate the two daughter cells during meiosis II, so zygote A and zygote B share the same placenta, once the twins are different genders, freemartin and chimeras happens.

Two eggs(share 100% identical genes) × Two sperm(share 50% identical genes)

What if both even splitting happened during meiosis I and meiosis II? The four sperm are still random, so the Quadruplets share their 50% genes on their father's side, and zygote A and zygote B is three quarters identical twins, zygote A and zygote C are quarter identical twins.

Four eggs × Four sperm(share 50% identical genes)

Plus identical twins and fraternal twins, here we can get 4 types of twins; the genes share rates are 25%, 50%, 75% and 100%. I think these situations have the name as “Polar body twins”, I do believe it can happen by accident. As polar bodies and the egg can not be properly separated, the polar twins share the same placenta, so they easily become chimeras. If they are different genders, the result is the female one will be affected by the male one in vulva development. My theory to case of "semi-identical" twins is they are just the result of the case of polar twins plus the case of fertilization by different gender sperm. I think it make sense that if they share the same gender, we can’t find them. Whatever traditional monozygotic twins or fraternal twins, they don’t share the 25% or 75% genes. We have found out the 75%, till we find out the twins who share 25% genes: they share no genes on their mother's side, but share only half their genes on their father's side, then we no longer deny the polar twins’ existence. I do think the “Semi-identical” twins which BBC reported is just this result of three cases: three quarters identical twins plus chimera and freemartin.

I think the case of Lydia Fairchild is not closed, we can check the two different sets of genes on her body, and then we can figure out what kind of twins before they fused. Above three examples are female were interfered by the male hormone more or less, but sometimes androgen got the bad luck.


Androgen insensitivity syndrome (AIS), formerly known as testicular feminization, is an X-linked recessive condition resulting in a failure of normal masculinization of the external genitalia in chromosomally male individuals. This failure of virilization can be either complete androgen insensitivity syndrome (CAIS) or partial androgen insensitivity syndrome (PAIS), depending on the amount of residual receptor function. In short, these defects make the body unable to respond to the androgens that produce a male appearance.

Human embryos develop similarly for the first six weeks, and the indifferent gonads begin to differentiate according to genetic sex. If the karyotype is 46, XY, testes develop due to the influence of the Y chromosome's SRY gene. This process does not require the presence of androgen, nor a functional androgen receptor. Then in the next process, what if mutation happens in the AR gene and the function of the androgen receptor (AR) is impaired. This gene provides instructions for making a protein called an androgen receptor. Androgen receptors allow cells to respond to androgens, which are hormones (such as testosterone) that direct male sexual development.

Apparently, the example of freemartin illustrates that, due to the exterior strong hormone (testosterone) interference, despite the presence of ovarian, the accessory sex glands still go to the direction of male, but the genotype is 100% sure of XX. Conversely, the example of AIS illustrates that, when the expression is blocked, despite the presence of testosterone, the accessory sex glands still go to the direction of female, but the genotype is 100% sure of XY.

Individuals with CAIS are raised as females. They are born phenotypically female and almost always have a heterosexual female gender identity; the incidence of homosexuality in women with CAIS is thought to be less than unaffected women. Because of this, we can get if the gay genes really exist on chromosomes, it doesn't have any concern with sex chromosomes.

The two examples of freemartin and AIS can apparently illustrate that together, in mathematics, the sexual expression which controlled by gene is a piecewise function. First step, the gonad (testes or ovaries) is synthesized by SRY on the Y chromosome or by some genes on X chromosome. Of course, in mammals, the genes which control the expression of testis are completely dominant genes, compared to the genes which control the expression of ovarian. Second, some specific hormones, released by testes or ovaries, control the growth direction of other accessory sex glands, whether labia fused or not, the clitoris shaft became big and wrapped urethra or not, the gonad descend or not. This two steps both control a person whether abnormality or not step by step.

Here I want you to think how we should define the sex of AIS, depending on the genotypes or expression traits? Do you think it is OK that the person with AIS marries a male, if you are against Gay marriage? 

In GSD animals, how do we define the genders? We should define it depending on sex genotype or expressive traits? If we choose expressive traits to distinguish the two genders, does it depend on gonad, primary sex characteristics, or secondary sexual characteristics? It is very complicated to classify on this issue.

3, Another thorny issue: hermaphrodite

From the view of genes

As long as there are two different sex alleles on your chromosomes, you can be identified as hermaphrodite. In other words, if your sex genes are not homozygote, you are hermaphrodite. In my theory, male with XY chromosomes in mammals and female with ZW chromosomes in birds are all hermaphrodites. The reason, why sometimes testis genes become dominant genes in some species and sometimes ovarian genes become dominant genes in some other species, all depends on the environment of the sex genes, not only the natural environment, but also the genes environment. Apparently, the environment in birds determined that ovarian gene is dominant, but recessive in mammals. Anyway, whatever the environment determined which sex genes is dominant, it doesn’t change they are hermaphrodites from the gene view. XY and WZ are both Heterozygous in sex genes. 

From the view of sex phenotype

Compared to birds and fish with simple reproductive system, mammals have more complicated system. For example the difference between male and female in birds and fish is just in gonad, but no big much difference in the vulva between the sexes, so I think that is why sex reversal always happen on fish. In mammals, because the vulva between the sexes is very different, there is no chance to make sex reversal at all. So I think it can be divided into three different situations. 

Gonad: As long as the testis and ovary both exist, we can call them as hermaphrodite. This case basically can’t happen on animals, but only some plants. Some flowers that contain both sexual flower parts (stamen and pistil) are called perfect or bisexual while those that contain either stamen or pistil only are called imperfect or unisexual flowers, regardless of whether they lack sepals or petals. We can call this case as true hermaphrodite, and I think it can’t happen on human, except for chimera under one condition two different cells in primary gonadal. Flowers with both stamens and a pistil are capable of self-fertilization, which does increase the chance of producing seeds but limits genetic variation. The separation of the male and female sexual organs increases the possibility of outcrossing or cross pollination.

Subsidiary structure: The cases like freemartin and AIS which have the subsidiary structures of the other gender because of some accidents. A genes of XX with female ovarian, but male vulva, or a genes of XY with male testis, but female vulva. How do we define the two genders now? I don’t think we should consider them as hermaphrodite. 

Shemale: Famous shemales are always from Thailand, and most of them were from poor families and injected external estrogen when childhood. As a woman, I have to say some shemales are really pretty, I can’t help myself looking at them. They still have XY male genes, testis, normal male vulva and all normal male primary sex characteristics, but female secondary sex characteristics due to man-made after birth. Injection estrogen from outside only can change the secondary sex characteristics, but can’t change the genes, gonad and other accessory sex glands. How do we define them? Male? Female? Or hermaphrodite? 

Sex reversal

Sex reversal is very common in fish. Fish that can alter their sex are known as successive hermaphrodites. Normally the sex reversal occurs only once. For example, a sexually mature female reproduces and then becomes a male. The ovaries shrink, the fish develops testes, and male hormones are released. These physiological changes also alter the animals’ behavior. New males become aggressive, defend territory, and court females. In China's countryside, occasionally the kind of thing that hen becomes cock happens, but we never heard that cock becomes hen over night. Why? What if in some fish whole life, they don’t have sex reversal? Should we call them as hermaphrodite? Whatever they have sex reversal or not, their genes never change, right? 

4, What are the genders exactly?

What can we learn from above? Do you lose yourself in my words? What is homosexuality? What is heterosexuality? Before we define someone is homosexual or heterosexual, we have to figure out how should define the two genders. What about the birds with WZ chromosomes and fish? There is no big difference between two sexes, because neither sex has penis. Birds choose cloaca kiss to fertilize, and fish basically are in vitro fertilization. Our human can’t even define the genders clearly, not to mention homosexual or heterosexual. Homosexuality is simply a false proposition.

Richard Dawkins wrote his opinion about genders in his book - The selfish gene “We simply accepted that some animals are called male, and others female, without asking what these words really meant but what is the essence of maleness? What, at bottom, defines a female? We as mammals see the sexes defined by whole syndromes of characteristics - possession of a penis, bearing of the young, suckling by means of special milk glands, certain chromosomal features, and so on, These criteria for judging the sex of an individual are all very well for mammals but, for animals and plants generally, they are no more reliable than is the tendency to wear trousers as a criterion for judging human sex, In frog, for instance, neither sex has a penis. Perhaps, then, the words male and female have no general meaning. In gene’s long journey down the generations therefore, an average gene will spend approximately half its time sitting in male bodies, and the other half sitting in female bodies.”

I do think our humans like to classify too much, fat and thin, high and short, white and black, man and woman, but we really ignore something very rare – true love. In long history of evolutionary: sexual reproduction showed up first; then penis intercourse, we have to admit that until now there some animals on earth that can reproduce but no penis intercourse, like IVF in fish or cloaca kiss in birds; and then marriage, until now I don’t think not every marriage is because of love, especially in patriarchal society, the purpose a woman get into a marriage is for survival, because women can’t go to school like boys, can’t go out to work like man, but only marriage for living; finally love, to be honest, I do not think love is necessary in evolutionary. The only purpose of non-human having intercourse is only for reproduction, not for love. So far in lots of human being countries, men only care about the possessive quantity and quality of women, and women only care about how much interests one man can offer to her. This is just a sale, not love. The nature of this relationship is as same as clients and prostitutes. Unfortunately, I live in this dynasty.

Let's go back to genes, in my theory, the testis and ovary genes are just an ordinary two alleles as same as single eyelids and double eyelids genes on autosomal. Don’t tell me the reason you think someone with single eyelids can only marry someone with double eyelids, is just because they don’t share the same trait on eyelids. Our human, as only one intelligent life on earth, should see the essence of things through outward appearance. Every person has 46 chromosomes; in other words, do not let one chromosome which only occupied the probability of 2.17% covers your heart. Just love someone following your heart.

What is love? Love is simple, to be together. If one day, women can wake up from the daydream of self-deception to find their self-consciousness, nothing is going to prevent two people being together, no matter a man with a woman, or two women, or two men. 

Love is being together.

By the way, I saw some news that female orgasms increase the chance of fertility, and women can have orgasms during child birth. I am almost so mad to hematemesis!!!