Questions tagged [sex]

Questions involving the study of sex and reproduction, mating systems, sexuality, sex determination, gender, the evolution of sex, and other topics in the context of sex.

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Why boys who inherit more genes of their mother are not born as girls and girls who inherit more genes of their father not born as boys?

If boys as well as girls inherit the genes of the father as well as mother, does it imply that boys inherit more genes from the father to be boys and the girls inherit more genes from the mother to be ...
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342 views

Why females don't have much sexual desire when compare to males? [closed]

I read this Wikipedia article about Playgirl, It is made especially for females. but Its Spokesman Daniel Nardico revealed subscriptions are generated more from males. In a February 2010 interview ...
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1answer
223 views

Is there a theoretical maximum on the number of sexes a given species can have?

Background: To the best of my knowledge, most sexually-reproducing species of organism have two sexes, although there are also sexually-reproducing species of organism (flatworms come to mind) which ...
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2answers
171 views

What are the distinct neurochemical components of sexual pleasure?

Sexual activity is usually described as pleasurable. What neurochemical systems does sex activate? Does the presence or absence of a partner make a difference -- say, in the activation of the ...
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2answers
674 views

Why would a human female have a sexual display despite male biased operational sex ratio? [closed]

why would a human female have a sexual display despite male-biased operational sex ratio? In human society there is a male-biased sex ratio, due to female child rearing, which results from anisogamy. ...
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1answer
87 views

Why human endometrium doesn't stay constant? [duplicate]

Is there any explanation or evolutionary advantage to the endometrium constantly cycling between the proliferative and menstrual cycle? Wouldn't it be more advantageous if it kept always fully ...
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1answer
219 views

Are all non-breeding naked mole rats the same sex?

In many eusocial species, all the non-breeding members are the same sex. Honeybees are a good example, with only female workers. Are naked mole rats that do not breed also all either male or female, ...
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0answers
86 views

Are oysters really aphrodisiacs?

Oysters have been thought of as aphrodisiacs for millennia. Is this a case of the bark of a willow tree as a precursor to modern paracetamol, or some sort of marketing ploy. Is there any biological ...
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1answer
403 views

How spinal cord play its roles in human beings sex? [closed]

I know most people can't enjoy sex if their spinal cord injured. How spinal cord play its roles in human beings sex?
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427 views

Where does new blood comes from when penis get erected? [duplicate]

In Humans, During sexual arousal in males, his penis will get erected with blood. Where does this new blood coming to fill his penis which is required for erection ?
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1answer
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Are humans not sexual dimorphic? Can genetic XY but SRY not expressed become pregnant? [closed]

My understanding was that XX/XY was how sex is determined in mammals, and so humans as well. A science teacher posted this regarding transphobia: "I just commented this on a transphobic post that ...
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1answer
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Is female the default sex in humans?

I was taught in school that female is the default sex in humans based on the following logic: Development into a human male requires the activation of the SRY gene in the foetus. If that doesn't ...
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1answer
72 views

Is the term 'allele' specific to sexual populations?

I had always thought that 'allele' simply meant a variant of a gene and thus could be used in the context of either asexual or sexual populations. With it only being slightly less useful as a concept ...
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What's inside the males body in the space where females have the ovaries and the uterus?

The male penis and scrotum are external extremities, whereas the female sex organs are placed "inside" the body. So as females have the bladder, rectum, other stuff just like males. Does this mean ...
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1answer
1k views

Why do women mature (physically) earlier than men? [closed]

All sources I've read (the first page) states that the fact that women mature (in the sense of physical maturing) earlier than man is caused by the earlier selective prunning in brain. Though, this is ...
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How is trangender female different from normal female biologically?

I have read in many places that transgender people are usually people who are born with typical male or female anatomies but feel as though they've been born into the “wrong bodies.” The thing that I ...
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1answer
135 views

Is there any evolutionary reason for why some organisms (wrasse) change their sex in adult stage?

In San Francisco, I saw this fish: and quoting the aquarium's page: Part of the wrasse family, the California sheephead is a protogynous hermaphrodite. Simply put, all sheepheads are born as ...
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1answer
209 views

Stem cell and organ growing genitals [closed]

I've been reading a lot about stem cell research and the work on growing artificial organs. I assume, with sufficient advance in the technology, there is no theoretical reason it would not be ...
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114 views

Why does female's age of puberty inform on mating system?

Reading from Does increased calorie intake cause increase in libido in humans?, @AlexStone says: I'm aware that humans have a dual mating strategy - somewhere between pair bond and casual mating. ...
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6k views

What is the evolutionary advantage of having pubic hair?

Only humans have pubic hair. What is the evolutionary advantage in having it?
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Are there genes in sex chromosomes that determine facial features?

My friends and I were bored enough to try out this activity. Picture a teenage boy in your mind. From this picture, remove any accessories (glasses, piercings, etc.), moustache or beard, then replace ...
4
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1answer
3k views

Why do humans masturbate? [closed]

Why does masturbating seem to be like an addiction? What controls or initiates the urge to masturbate? Is it good or bad or both and why is it so? I have heard guys who say that the do it ...
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1answer
635 views

Acrosomal enzymes and the female reproductive tract

My textbook wrote that the reason why acrosomal enzymes are so securely contained within the sperm (thus needing capacitation to facilitate their release) is to prevent any premature release in the ...
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2answers
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Are gametes determined by the sex of an organism?

In the Wikipedia article for biological sex, I read the following sentence. "The gametes produced by an organism are determined by its sex:..." However, is it not through the gametes produced by ...
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1answer
572 views

Are there animal species with sex of an offspring determined by sex of preceding offspring?

For instance, if an animal's first offspring is male, then all subsequent offsprings will be male too (the sex of first offspring could be determined randomly). Does it happen in any species?
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Why did life on Earth develop with two sexes? [duplicate]

If evolution gives us the best adapted organisms for survival of the fittest, why does so many of Earth's organisms require two sexes for reproduction? Shouldn't this have been bred out of our ...
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495 views

Why are there no complex hermaphrodite land animals? [closed]

The title says it all. I know that 'complex' is a pretty ambiguous term to use, but I can't think of a more scientific term/definition for my meaning. I can't think of any large (larger then a small ...
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187 views

What form of reproduction did the first land animals use?

What form of reproduction did the first animals on land use*? Were they hermaphrodites, or did they have male and female sexes? [Is there a proper term for sexual separation in a species?] Were any ...
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74 views

What is the advantage of being tired after having a sex? [duplicate]

When we have a sex with partner, we feel so tired that we don't have any power to do anything. Then it would be disadvantage to the animals, of course humans too, for they are exposed to danger. For ...
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1answer
4k views

How do you identify a mosquito's sex without letting it bite you? [closed]

Are there any reliable indicators?
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3answers
964 views

If the haploid prothallium of a fern fertilizes itself into a diploid sporophyte, does this make all ferns clones?

From what I understand in the alternation of generations in ferns, mature spores germinate into a haploid prothallium. But how does this gametophyte produce recombinant gametes if it itself develops ...
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3answers
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Is homosexuality an adaptation in humans?

Homo sapiens have menopause - as some other mammals (e.g. some Cetacea) - a phenomenon where older females live for decades after the end of their own reproduction. Perhaps homosexuality, that looks ...
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261 views

How many mitotic divisions do haploid cells undergo before fertilization?

Background This question is about human physiology and gametogenesis. A spermatozoid is not necessarily the direct "offspring" of a diploid cell. Stated differently, a spermatozoid cell can be the ...
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What's the difference between male and female?

As long as we only look at humans the differences are clear: males have chromosomes XY, produce sperm and don't get pregnant. Females have chromosomes XX, produce egg cells and bear babies. But when ...
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118 views

Why can't there be fructification of mycelium in submerged culture?

I am very new at this. I am wondering why fed batch cultures produce a lot of mycelia but no fruit. I thought the more mycelia you had, the greater chance of it forming a fruit body. I am refering to ...
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Why sperm count matter for pregnancy?

In order for a woman to become pregnant, sperm is needed. Why is sperm count so important for pregnancy? http://en.wikipedia.org/wiki/Sperm
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Do males of all sexual species have Y chromosomes?

I know for instance some cells are sexual, so, this got me wondering, do the males of all species that have distinct sexes have Y chromosomes?
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1answer
687 views

When did our ancestors switch to a menstrual cycle instead of the estrous cycle?

The Wikipedia page on the Estrous cycle says: Humans have menstrual cycles instead of estrous cycles. They shed their endometrium instead of reabsorbing it. Unlike animals with estrous cycles, ...
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Skin porosity in glans penis when erect

(Apologies if this is a too weird/inappropriate question in this forum. I only thought that I ask it since it happens to be part of human life.) The skin on a human typically blocks many substances ...
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1answer
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In males, why it is difficult to control orgasm?

Why it is difficult to control orgasm in male humans? How are orgasms controlled and what is different between males and females? We can control urine for few minutes, but we can't control orgasm for ...
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1answer
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Evolutionary reasons why you cannot tickle yourself but masturbate

There are obviously good reasons that explain why you cannot tickle yourself (see e.g. here). This got me thinking why it is possible to masturbate... Wouldn't it make more sense to not being able to ...
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Why does sex last so long?

I wonder why (especially human) sex lasts longer than just a few seconds? My thought is that the shorter it takes a man to ejaculate, the lesser is the risk that he gets interrupted by a rival or a ...
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0answers
258 views

Why is gynodioecy common and androdioecy rare?

Gynodioecy is when a population features individuals that produce both male and female gametes and individuals that produce just female gametes. Androdioecy is when a population features individuals ...
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1answer
545 views

Are there multicellular isogamous species?

Are there multicellular isogamous species? Seeking through the examples of wikipedia I would tend to think that there are no multicellular isogamous species.
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Ancestral states of sex determination system

Most (maybe all?) species that reproduce sexually have either genders (anisogamy) or mating types (isogamy). There exist today many different type of sexual determination system. There is a whole ...
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491 views

What is most ancestral: isogamy or anisogamy?

Sexual reproduction can be feasible with anisogamy (gametes of different sizes i.e. genders) or isogamy (gametes of same size i.e. mating types) or with undifferentiated gametes (i.e. true random ...
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1answer
2k views

What is the result of meiosis?

Is the result of meiosis ONLY the sex gametes (male and female) which later meet to form a somatic cell? Sometimes I feel as if my book is hinting towards meiosis is the process where sperm cells meet ...
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3answers
115 views

sex limited genome transmission

In general, for dioecious species, a large portion of the genome passed from parents to offspring of both sexes - in mammals the X-chromosomes and autosomes are passed from a mother to both daughters ...
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381 views

Is there a difference between endorphins that are released while physical activity and sex/masturbation?

I observerd myself and I can identify two different types of "happines". First - called by me - After Pleasure : Occurs AFTER (and last long) long activity that require from me engagement focus and ...
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2answers
226k views

Teens concerned about impregnation through clothes

Dry Humping, is: dry humping is the process of two people repeatedly moving up and down and back and forth on top of each other fully clothed( or missing various pieces, but the penis must not come ...