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11

Update -- In the time since this question was asked, two relevant articles have been published, one in Nature Reviews Immunology and one in medRxiv (note: medRxiv is a preprint server and is therefore not peer reiewed). Scully, E.P., Haverfield, J., Ursin, R.L. et al. Considering how biological sex impacts immune responses and COVID-19 outcomes. Nat Rev ...


7

The title question, Is there any evolutionary reason why male traits appear in the heterogametic sex and female traits in the homogametic sex?, suggests that male always is the heterogametic sex, but this is not true. ("Male" is usually defined as the sex with the small, mobile gametes, i.e. sperm, as contrasted with the large, nutritive gametes,...


4

In brief, so far as we can tell size matters far less than brain architecture. Consider that humans have only about half as many cortical neurons as a number of whales, yet are clearly far more intelligent. While we are still far from a complete understanding of the details of how intelligence actually works, neuron count is only part of the story. For ...


4

This sort of thing absolutely happens; useful search terms are "sex ratio distortion", "segregation distortion" (i.e. modifying the ratios with which different chromosomes segregate), and "meiotic drive" (a specific form of segregation distortion). Your scenario (Y-chromosome genes forcing all offspring to be male) is much less ...


3

It is confusing. The septum pellucidium is a thin membrane separating the left and right lateral ventricles. It contains white matter (nerve fibers), blood vessels and a few neurons. It has traditionally been thought of as just a separating membrane, but the fibers running through it connect to the hippocampus and hypothalamus and so it is probably a ...


3

"Intrinsic hypothalamic fibers" are fibers instrinsic to the hypothalamus; so yes, these are fibers either projecting from somewhere in the hypothalamus to somewhere else in the hypothalamus, or locally in the hypothalamus (the hypothalamus itself is a pretty complex structure containing many distinct nuclei). The paper you reference specifically ...


2

Your observation is right. In females( having XX mammalian germ cells), Oogenesis starts with the process of developing primary oocytes, which occurs via the transformation of oogonia into primary oocytes, a process called oocytogenesis. Oocytogenesis is complete either before or shortly after birth.(1) The "germ cells" are called oogonia. Ovum ...


2

I think that you will find that the opposite is the case more often. First of all, a premise that XX vs. XY has some kind of fundamental truth (which really is a premise of this question) is simply incorrect. There are a wide variety of karyotypes of the sex chromosomes, and these do not line up well with common notions of sex. Using the XX vs. XY heuristic, ...


2

Pareidolia is a common phenomenon, and certainly is not limited to "seeing" phallic or other objects as sexualized; the canonical example is seeing objects as face-like, such as the headlights and grill of a car appearing as eyes and mouth. There seem to be some sex-based differences in pareidolia (see Proverbio 2017) but if there is hormonal cause ...


1

It depends on whether mutation exists. Generally mutation is happening in biology, but in its absence, yes it will be at or near zero: Note that in the absence of any mutation, $F_{ST}$ would be defined but equal to 0, as all the genetic variance is within individuals and none between individuals and subpopulations. From that paper, see this figure: So, ...


1

Firstly, those aren't bumblebee faces ... those are big fly eyes. Those are Bumblebee Hover Flies (Volucella bombylans): The noise in the first part of the video is identical to a fly flying around your head and the noise at the end sounds like what a fly would sound like when you press it against a surface like a wall or screen (or a newspaper, apparently)


1

I may have misunderstood your question, but there is no theory why usually reproductive costs are on the female, as this is a fact. Females have usually larger (and fewer) reproductive cells (gametes), they frequently have to carry the embryo until birth, and sometimes they have to attend to the offspring during the first stages of their lives. To put it ...


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