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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1answer
3k views

How can I determine the sex of a tree seedling?

I would like to plant some home grown female mulberry trees in a circle, with a male plant in the center for pollination. How do I determine the gender of a tree seedling? I know it's possible, ...
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1answer
404 views

Do reproductive organs function before puberty?

Testis means one of the two male reproductive glands that produce spermatozoa and secrete androgens. Ovary means one of usually two organs that produce oocytes and secrete oestrogen and progesterone. ...
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162 views

Do ovaries produce estrogen before menarche?

It is traditionally taught that estrogen is produced by the granulosa cells of the follicle. But before menarche, where does the estrogen come from? Is it from the thin layer of granulosa cells lining ...
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1answer
143 views

Why are worker ants not clones of the queen?

Currently worker ants of most species share only three quarters of their genetic code. It seems like worker ant clones would be better, as it would remove all genetic conflict of interest between them....
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101 views

Which scallops change their sex from male to female?

Tonight it occurred to me to look up what scallops are like when they are alive (beyond their culinary role) and it blew my mind. This post regards one detail about which I was unable to find specific ...
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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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1answer
136 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
810 views

Does orgasm cause a dopamine crash?

There's some theory around that orgasm will cause a dopamine surge and drop, and that this can lead to a period of low mood or depression. A come down. Is this true, does orgasm have a negative ...
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66 views

Number of alleles' variations in a mushroom that has over 20,000 sexes

I am trying to understand the mating behavior of a particular species of fungi known as Schizophyllum commune, or the split-gill. I found a blog post that explains the mechanisms that define the ...
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How does temperature affect sex drive in humans?

I've ran into a science journalism piece which reported on a NBER study fidning that lower human fertility following hot temperatures over 80 degrees Farhenheit. They attributed this effect to ...
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1answer
92 views

Which species has the highest proportion of homosexual individuals?

Are there more homosexual individuals in ducks, humans, or some other species?
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484 views

How Excessive masturbation can make a person unfit for army? [closed]

Recently I saw this news trending, I never heard single disadvantage regarding masturbation. But China Army considering it has danger for army. So How Excessive masturbation can make a person unfit ...
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8answers
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Does any animal species have two sexes and more genders?

Are there any animal species that have two sexes and a kind of different internal diversification in two genders or more? I don't mean something like different-task-based diversity, but something ...
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2answers
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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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2answers
20k views

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
225 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
678 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
89 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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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
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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1answer
1k views

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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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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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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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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2answers
25k views

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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2answers
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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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2answers
718 views

Why are there so many sex determining systems in animals

There are several sex determining systems in animals. In mammals XY = male(except in rare cases where SRY crosses with genes on the X so that it is the reverse) and XX = female. In some birds it is ...
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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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2answers
692 views

How and when did sex evolve?

As I know evolution comes bit by bit mutation by mutation How sex evolved which requires a major change in at least two individuals one to become male and one to become female ? When that happened ...
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0answers
115 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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1answer
36k views

What is the standard deviation of adult human heights for males and females?

The wikipedia article on human height reports mean height for many different countries by sex but it does not report standard deviations. What is the standard deviation of adult human heights within ...
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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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1answer
79k views

What is the female equivalent of the morning erection that some men experience?

There was question about what causes "morning wood." It was answered that the erection in the morning is caused by decline of norepinephrine during REM sleep. Which in part allows to prevent ...
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2answers
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Can animals, like monkeys, be homosexual?

I heard that some monkeys can be homosexual? a friend of mine was saying that he saw a male monkey having sex with another male monkey in the zoo, I honestly didn't believe him, I think he just got ...
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2answers
1k views

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 ...
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228k 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 ...
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3answers
4k views

Do women experience more bonding hormones than men after sex?

Does Oxytocin (or any other bonding hormone) increase more so for women than for men after sex? Someone told me that it increases 4-fold for men and 12-fold for women (unconfirmed). Is there any ...
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2answers
2k views

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
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
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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0answers
87 views

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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2answers
11k views

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
190 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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0answers
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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0answers
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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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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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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 ...