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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-1
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0answers
20 views

sex ratio and population size (or survival rate)

Does anyone know a research article which states that male biased sex ratio (smaller number of female) decreases population size (or survival rate of the population)?
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39 views

Why do we need only 1 X chromosome?

In females, one of the X chromosomes will be deactivated randomly to form a Barr body. Why do barr bodies form? We have 2 copies of any other chromosome. Why don't they form for our 22 other ...
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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 ...
4
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1answer
76 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
141 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
8k views

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 ...
2
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1answer
22 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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3answers
962 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 ...
7
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1answer
459 views

Can you tell the sex of a white willow when it's not flowering?

Can you tell whether a salix alba tree will produce male flowers or female flowers by looking at it, touching it or generally using your unaided senses? If not, is there any way to do that without ...
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1answer
34 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?
2
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1answer
53 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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2answers
71 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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0answers
30 views

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
83 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 ...
7
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1answer
676 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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0answers
50 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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0answers
15 views

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
63 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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0answers
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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1answer
58 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 ...
0
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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 ...
4
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1answer
123 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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2answers
359 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
69 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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0answers
34 views

Silly question about two human mechanisms: induced “REM dreams” by masturbation?

First of all, I'm a layman concerning Biological discussion. Well, my question is simple: is there any relationship between the hormones liberated by masturbation and REM phase of sleep? I'm ...
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779 views

Genetic expression in interspecific hybrids

Referring to interspecific hybrids, I have the following two questions:- Quoting from wikipedia:- The offspring of an interspecific cross are very often sterile; thus, hybrid sterility prevents ...
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1answer
61 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
49 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 ...
11
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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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0answers
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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0answers
75 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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0answers
47 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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2answers
228 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 ...
2
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1answer
149 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, ...
32
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2answers
5k views

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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1answer
25 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 ...
4
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1answer
169 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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1answer
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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2answers
274 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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0answers
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 ...
0
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1answer
185 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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2answers
4k views

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?
2
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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?
3
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1answer
500 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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2answers
608 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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0answers
89 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
311 views

Pseudosexual reproduction

Research projects with artificial life generally use creatures that are haploid. The offspring randomly inherit some genes from one parent, and some genes from the other parent. Q1: Are there any ...
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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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1answer
307 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 ...