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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17 views

Can a species stabilize with non-Fisherian (e.g. 3:1) female:male ratio?

A (possibly naive) idea that could make it possible is if the male genes contribution is inversely proportional to the female:male stability ratio. For example, if there's a population of 300 females ...
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49 views

Why does the friction of the sexual organs cause ejaculation?

What is the physiological mechanism?What kind of physiological phenomenon can friction cause? Why does friction produce orgasm and generate electric current in the body?
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1answer
50 views

higher-order evolutionary adaptations

Most adaptations are what I'd call first-order. Cats evolve better eyesight; redwoods evolve to grow taller; male cardinals evolve attractive bright feathers. All of these changes were selected for ...
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1answer
108 views

Why do women have less synapses / neurons / brain mass than men despite having the same average IQ?

I don't mean to cause offence or suggest than men and women shouldn't be of the same intelligence — that's not something I'm here to dispute. What I want to understand is how this is possible given ...
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2answers
152 views

When is it better for a gene to cause a biased sex ratio?

Because genes are selfish and want to maximise their transmission from generation to generation, if they can distort a population's sex ratio, isn't it always in their interest to cause a biased sex ...
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1answer
36 views

Will Fst (inbreeding coefficient) always be a value close or at 0 in asexual populations?

FST is the average inbreeding coefficient of a total population. The equation is: $F_{ST} = \frac{Var(S)}{Var(T)} $ $Var(S)$ = variance in the frequency of the allele between different subpopulations, ...
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1answer
35 views

Do hormones make it more likely to perceive sexual forms in otherwise non-sexual objects? [closed]

People can see sexual forms in many things. It seems that this varies with age, but this is not enough to claim it is because of sexual hormones. The question is: is it?
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1answer
61 views

Is there any evolutionary reason why male traits appear in the heterogametic sex and female traits in the homogametic sex?

If you define male as the heterogametic sex, and female as the homogametic sex, then my question sounds like a tautology. But, what I'm trying to get at is why is it that the traits we associate with &...
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Flatworms sexual reproduction; one must be the mother and the other the father?

I watched this. I wonder if both of these flatworms ever end up pregnant. Earthworms are simultaneous hermaphrodites, meaning worms have both male and female reproductive organs, just like flatworms. ...
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1answer
130 views

What causes the sound of climaxing bees?

I just saw the funniest video of bumblebees(?) having sex. (mirror) As they were getting it on, there seemed to be an almost audible 'moaning' coming from the pair. From what I presume it was a sexual ...
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Can bacteria (dis)assortatively mate?

After revising some evolutionary concepts, I stumbled on the "big five" of evolution (e.g., mutation, selection, mating, genetic drift, gene flow). I wanted to understand if mating as in &...
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1answer
65 views

are there examples of research harmed by the binary vs. non binary genders discussions? [closed]

As a base for my question, here is a link to an article from nature.com: https://www.nature.com/articles/d41586-020-00502-w In the article, the following paragraph is relevant: The researchers ...
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18 views

Empirical Measurements of Barr Body Ratio

'Both X-chromosomes in a female have an equal chance of becomes a Barr body in each cell.' Every source I can find on Barr bodies claims this and I can think of no reason for why it may be wrong. What ...
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2answers
75 views

Why do the two sexes have different reproductive costs and capabilities?

Is there an evolutionary explanation that shows why the reproductive costs are mostly on the female sex? And therefore, why do males can potentially have more offspring? Does that happen to create ...
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1answer
64 views

What exactly is “lateral septum”?

I came across the phrase lateral septum and I can't seem to find the precise definition online. Is it "the areas roughly to the right and the left of the septum pellucidum"? Or is it the ...
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1answer
35 views

What are “intrinsic hypothalamic fibers”? (From an article on neuronal mechanisms of sexual desire)

I came across the phrase intrinsic hypothalamic fibers which I cannot understand. What is meant by intrinsic - that these fibers (long myelinated axons?) start in the hypothalamus? Or that they start ...
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1answer
189 views

Germ cells vs. gametes

Naively, I thought that germ cells are diploid (in diploid species like human/mouse at least). Then, germ cells undergo meiosis and become haploid. I thought this was the critical change that defined ...
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1answer
75 views

Y chromosome changing sex ratios

Fisher's principle explains why sex ratios in most sexually reproducing species is approximately $1:1$. However, given that in humans and many other animals, males and females differ genetically, it ...
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682 views

Why are men more susceptible to severe COVID-19?

It seems that globally, men are more susceptible to severe COVID-19 than women: https://www.theguardian.com/world/2020/mar/26/men-are-much-more-likely-to-die-from-coronavirus-but-why This is seen in ...
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51 views

Is it impossible for some female songbirds to sing?

I have read that in northern hemispheres, most female songbirds can't sing (for example, the Blackbird). Things are different in tropical regions. Birdsong is for males in some species; it is utilized ...
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1answer
62 views

Large study showing that attraction to only the same sex has to do with your genes, published where?

Can someone please help me out and find and link me the study from a couple of years ago that showed how only same sex attraction, when the male cant become attracted to a woman, it has to do with ...
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1answer
58 views

If someone with “XO” is one of the identical twins with the other twin as male, then what would the sex chromosome of the other twin be?

A more complete question: If someone with sex chromosome of XO is one of the monozygotic twins with the other twin as phenotypically male, then what would the sex chromosome of the other twin be? I ...
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58 views

What is the developmental and health outcome of an XY individual with an SRY addition on their X chromosome?

I know that "XX male" syndrome occurs through various means, including the addition of an SRY gene in one of the X chromosomes. The developmental and health outcomes of such individuals can be ...
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77 views

Evolution of the unique mating system of the scorpion Androctonus australis

Sperm transfer in the scorpion Androctonus australis involves a sclerotized spermatophore, which is formed in the paraxial organs of the male reproductive system. The right paraxial organ produces the ...
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3answers
1k views

Is sex a spectrum?

At the moment I'm especially interested in the question of whether biological sex is really a spectrum. Unfortunately I could not find any good answers on the Internet. Therefore I hope that some of ...
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50 views

How widespread in the Animal Kingdom is Aromatization as the Process that Determines an Animal's Sex?

I shall summarize my lay understanding of my question before going into details. To my lay reading, the sex of a vast diversity of animal kingdom species can be thought of as arising from the extent ...
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1answer
165 views

Is sexual desire stronger in men than women?

Usually in popular culture it's considered men sexual desire is stronger than women. This seems to be congruent with the availability of sexual related items for men and women, such as magazines, ...
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1answer
26 views

How does X chromosome monosomy occur

I want to understand how Turner syndrome - monosomy X - occurs at the molecular level. The NIH mentions that there are cases of both complete monosomy and of mosaicism. I’m particularly interested ...
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1answer
178 views

Evolution of the haplo-diplontic life cycle

From wikipedia > Biological Life Cycle: haplontic life cycle - the haploid stage is multicellular and the diploid stage is a single cell, meiosis is "zygotic". diplontic life cycle - the diploid ...
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2answers
377 views

Why are (some) male humans sexually attracted to the breasts of female humans? [closed]

Many male humans are sexually attracted to the breasts of female humans. Is there an evolutionary reason for this?
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1answer
186 views

Why is sex hurtful for some animals but pleasurable for others?

Sex seems to be pretty hurtful for feline for example. On the other hand sex is pleasurable for humans. Why is sex pleasurable for some and not for others? How do these things evolve?
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232 views

Can diet, supplementation and/or drugs affect sexual dimorphism?

After puberty, can certain diets, exercise, and/or possible drugs affect masculine/feminine dimorphism in adults? We know dimorphism and/or morphology is a product of genes, but to what extent can ...
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90 views

Are humans the only primates being engaged in group sex?

There are quite many examples of humans being involved in group sex. I won't say it is a common thing and won't say whether it is "natural" or "cultural" (but "cultural" only means induced to majority ...
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2answers
299 views

In men, why do over 80% of sperm have abnormal form? [duplicate]

Here is the percentage of normal forms among fertile mens according to the centile (Source: Cooper et al. 2010): 2.5: 3% 5 (below this is Teratozoospermia): 4% 10: 5.5% 25: 9% 50 (median): 15% 75: ...
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3answers
5k views

Why do hot water baths affect only males' fertility? Why not females'?

Here is the link where urologists are warning men not to take hot water baths. Why does it affect only males' fertility? Why not females also?
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4answers
1k views

Are there lifeforms that have more than 2 sexes?

Are there any lifeforms on earth that have more than male and female biological sexes? If so, are all three mates required for reproduction or is there something else going on? If not, why not? ...
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1answer
406 views

Is it Theoretically Possible to Create a Male clone from the donor Cell of a Female?

I understand that Dolly the Sheep was created without the presence of a sperm cell. Instead, nucleus DNA from somatic cells of adult sheep were used. Since Dolly was female, i am assuming that the ...
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1answer
431 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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165 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
147 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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102 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
546 views

Sex determination in cephalopod?

I see some source say octopus do not have sex chromosome. So what's the sex determination mechanism for cephalopods?
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1answer
16k views

How many genders are there? [closed]

These days it is often contested how many genders is there. So my question is how many genders is there and is it unnatural for evolution to generate multiple genders.
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622 views

Can you tell if a corpse was male or female by only examining its skull?

There are articles that says women have more rounded corner faces than men, than women noses are usually shorter, etc. But are those (and other features) tendencies or deterministic features that ...
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1answer
816 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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3answers
25k views

Are male and female brains physically different from birth?

Male and female brains are wired differently according to this article: Maps of neural circuitry showed that on average women's brains were highly connected across the left and right hemispheres, ...
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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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2k views

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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485 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 ...