🧵 Does the Y chromosome evolve faster?
Anonymous at Sat, 7 Sep 2024 00:39:18 UTC No. 16364841
I'm gonna get crucified for this one, but I'm actually hoping someone with a biology background can explain why I'm wrong.
We can trace mitochondrial DNA which goes back entirely through maternal lineage. We can trace Y chromosomes back through paternal lineage. Studies have done just that and found that historically the ratio of female to male reproduction was 2 to 1. 10,000 years ago it was like 17 to 1.
There's also been research showing the Y chromosome has shrunk dramatically in the last million or so years.
Now in terms of mutation rate the Y chromosome isn't going to mutate any faster. But deleterious traits should be removed significantly faster from the Y chromosome due to much stronger selective pressure, creating a bottleneck while the X chromosome is under much less pressure.
Does this mean what I think it means? I'm hesitant to extrapolate but given the significantly elevated rate of anxiety and depression in women, I can't help but wonder.
Can someone please explain why I'm wrong?
Anonymous at Sat, 7 Sep 2024 00:55:18 UTC No. 16364859
>>16364841
Sounds plausible. Though the majority of defining characteristics are encoded on the autosomal chromosomes. The Y chromosome encodes for a smaller set of genes, signalling molecules and transcription factors that regulate the genes on the other chromosomes, but I'm not aware of exactly how much. It's an interesting research question. If you have the means, explore it. Bioinformatics is interesting and fun.
Anonymous at Sat, 7 Sep 2024 00:58:39 UTC No. 16364863
>>16364859
I am not even in that field. No way to research it. Was actually hoping to have someone smarter than me prove me wrong. You know how laymen often have shitty theories that miss some obvious detail anyone in the field would recognize immediately? I was hoping for such a detail due to my ignorance.
Anonymous at Sat, 7 Sep 2024 02:34:31 UTC No. 16365000
>Does this mean what I think it means?
I don't get it.
Anonymous at Sat, 7 Sep 2024 02:58:26 UTC No. 16365044
>>16365000
>deleterious traits should be removed significantly faster from the Y chromosome due to much stronger selective pressure, creating a bottleneck while the X chromosome is under much less pressure.
>given the significantly elevated rate of anxiety and depression in women, I can't help but wonder.
I think he's saying if it's true the X chromosome removes damaging elements at a slower rate than the Y chromosome, it would explain why genetically determined faults such as susceptability to mental disorders would be present in more females than males (as can be observed today). Saying X is the weak, slow link from an evolutionary perspective.
Am I wrong OP?
Interesting theory if so.
Anonymous at Sat, 7 Sep 2024 02:58:59 UTC No. 16365046
>>16364841
The Y chromosome doesn't really have that many genes left on it. It used to be an X chromosome that contained SRY, which became the main sex determining gene sometime in the Jurassic. The Y is just a simplified X. Everyone needs an X chromosome still, but two copies can sometimes interfere with one another. In males you can have both X and Y turned on because the Y is small enough that it doesn't interfere with the X much anymore. In females one of the X's becomes the dominant one and the other one is mostly silenced.
Anonymous at Sat, 7 Sep 2024 03:05:19 UTC No. 16365062
>>16365044
No that's dumb.
Anonymous at Sat, 7 Sep 2024 03:23:32 UTC No. 16365101
>>16365046
Not necessarily true as different regions have different x-chromosomes, which is how calico cats exist. So it's not just one X-chromosome, it's just random which one is dominant in which reason
Anonymous at Sat, 7 Sep 2024 03:28:26 UTC No. 16365114
>>16364841
everything I know about Y-chromosomes comes from this blog post.
https://www.pienisalaliittotutkimus
Anonymous at Sat, 7 Sep 2024 04:11:48 UTC No. 16365249
>>16365062
No as in you are OP saying that's not what you meant?
Or no as in you disagree that it's an interesting theory?
Use your words
Anonymous at Sat, 7 Sep 2024 04:45:12 UTC No. 16365318
>>16364841
The only purpose of females is to become breeding chambers. Any female who refuses to reproduce must be treated like a parasite.
Anonymous at Sat, 7 Sep 2024 07:24:40 UTC No. 16365451
>>16365044
Perry much yeah. If I were to put it as offensively and sexist-ly as possible, I'm saying this would mean women "evolve" slower.
Sounds shitty saying it like that but how else would I phrase it? Hence why I want someone to call me stupid via facts and logic..
Anonymous at Sat, 7 Sep 2024 09:33:04 UTC No. 16365543
>>16365451
While it is an interesting theory and may be true, in the specific instance of mental disorders that is not the explanation
In the case of depression for one it is not a monolithic entity
Melancholic depression (biological, unrelated to individual psychology) does occur twice as often in females as in males, but this is mostly due to the constant hormonal turmoil women go through related to menstruation. Episodes of melancholia are triggered by physical stressors, such as sleep deprivation, overexercizing, endocrine disturbances, neurologic diseases, and menstruation/menopause, to name a few. The latter obviously happening very frequently across a woman's lifespan, beginning at puberty (when melancholia usually first rears its ugly head in both sexes).
Nonmelanchic depression on the other hand is dependent entirely on individual psychology. It is not biological. The most often cause is cluster C personality traits. These are present equally between the sexes. Those traits are also the cause of anxiety disorders, again occurring with equal frequency between the sexes.
There are cultural differences in the application of diagnostic criteria which do not match the actual prevalence rates of these disorders (i.e. rampant overdiagnosis). This is most visible with the diagnosis of "major depression" (a 1980's creation blending together melancholic and nonmelancholic depressions, with incredibly loose and vague criteria which are easily inappropriately applied). Actual rates of melancholia are around 4%, and rates of cluster C traits no more than 10% across the globe. However depending on which country you visit those numbers are rarely matched in practice. Rates of major depression diagnosis are a whopping 20% of women in france, while in more diagnostically conservative countries such as china (which disregards nonmelancholic depressions entirely) the rates are about 5%, close to the actual rates of melancholia.
Cultural lens determines diagnosis.
Anonymous at Sat, 7 Sep 2024 09:59:43 UTC No. 16365600
>>16365451
>>16365543
For a practical insight to the issue of misapplied diagnostic criteria, take the common argument that women are more likely to complain and seek help. This is partly true. Depending upon culture, the same presentation differing by sex will elicit physician bias and diagnostic error.
Take for example this clinical scenario:
A man has not been feeling himself for a while. He's been experiencing palpitations, sweating, difficulty sleeping, and lack of ability to compose himself, among other things. His friends notice this and tell him to see a doctor. He explains these problems to the doctor, who brushes them aside as simple overwork or the result of poor diet. The doctor is biased to bieve men do not often suffer from emotional issues, underestimates the problem and misses the diagnosis of generalized anxiety disorder.
A woman has not been feeling herself for a while. She's been experiencing palpitations, sweating, difficulty sleeping, and lack of ability to compose herself, among other things. Her friends notice this and tell her to see a doctor. She explains these problems to the doctor, who tells her these are signs of depression which she must take medication for. The doctor is biased to believe women frequently suffer from depression, overestimates the problem and misses the diagnosis of generalized anxiety disorder.
In both cases the misdiagnosis hinges on the bias of the physician developed depending upon his culture. In the case of america, men must be stoic while the emotions of women are overcatered to. This applies in every circle if life including the medical field, composed of fallible humans. This results in idiosyncratic medical myths such as the belief women by default suffer anxiety and depression more than men. It's simply untrue.
Anonymous at Sat, 7 Sep 2024 10:09:25 UTC No. 16365616
>>16365543
>menstruation/menopause
I forgot the glaringly obvious imperative of the species
Pregnancy is one of the most common triggers of melancholia in women
Duh...
Anonymous at Sat, 7 Sep 2024 10:30:10 UTC No. 16365639
>>16364841
As other said, there aren't thst many genes on Y anymore. Moreover, to think that anxiety and depression are solely to be decretated on a gene level is pants on head tier.
[spoiler] some would say that only a woman could come up with something so stupid [/spoiler]
Anonymous at Sat, 7 Sep 2024 21:05:31 UTC No. 16366563
OP here.
So the theory might have validity, but the scope is so narrow as to be irrelevant. Because the Y chromosome encodes too little information which doesn't affect things like mental health issues or stress processing.
That helps a lot, thanks. Knew I was out of my element.