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This is region so highly conserved. The imprinting of genes on both the maternal and paternal alleles makes any genetic chaos here quite deleterious.

Since O16/O18 ratio is stable, does this let you go back farther than C14 carbon dating?

And accuracy decreases the farther back you go. Once you get around 50,000 years you’re at 10 half lifes, so any residual C14 is so small it’s not accurate.

I think you mean N2O4, which does indeed have an acrid odor. This is the dimer of NO2, and is in equilibrium with it, such that both species are present:

2 NO2 ⇌ N2O4

This is generally understood to be part of the mixture generically referred to as NOx. But point taken.

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To add to the other response you received, precipitation doesn’t have to be the same. The annual warming/cooling of the seasons leaves a mark like a tree ring (I’m simplifying), so they can differentiate precipitation years regardless of how much from each year.

None of it is exact, so they triangulate lots of different measurements to increase confidence.

For example, if you know a big volcano erupted 1,000 years ago, you’d look for ash at the depth the layers tell you is 1,000 years and see how accurate you were.

Objectively, no difference if your water in both methods is from the same source. Heat is heat. Your water might pick up some particles from the container it's in affecting the flavor in some small way.

Subjectively as a US tea drinker -

I find that filtered water makes terrible tea. It ends up flavorless. Spring waters and mineral water tend to make better tea to me. It's like the tea needs some sort of metallic content in the water to coalesce around to create flavor.

Water boiled in the microwave seems to cool off faster than water boiled on the stovetop or in a kettle. I've never measured it though. I drink it both ways but I tend to prefer tea made with water from the kettle. Maybe the metal kettle imparts some of its metal to the water. Maybe the water is hotter when it hits the tea than water from a plastic measuring cup in the microwave. Good tea should be "surprised" by the water so you should always pour water over tea rather than the put tea into water. I wonder how much of the subjective opinion of water preference has to do with which method people use? Perhaps when they use the microwave they are microwaving the water in the mug and then adding the tea to it rather than the other way around as they do when using a kettle. This does make a discernible difference in taste for good quality tea.

Given the immune environment of bats, it's thought that most hemorrhagic fevers are evolved from them.

https://www.nature.com/articles/s41586-020-03128-0

There has certainly been a lot of press around Kitum cave but there are earlier recorded outbreaks and the pinpoint origin really can't be said definitively since viral studies were pretty cutting edge 50 years ago.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166725/

https://academic.oup.com/trstmh/article/109/6/366/2461644

Of course, just saying it likely originated from bats doesn't really give the whole current story, there are many mammals that are thought to act as reservoir species so the cat is out of the bag...

https://www.science.org/doi/10.1126/science.1172705?url_ver=Z39.88-2003

https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004815

Took a little digging but Dorothy Tovar provided some great bat facts in this COVID AMA:

https://www.reddit.com/r/science/comments/ezstsw/science_discussion_series_the_novel_coronavirus/

It was my understanding that being heterozygous for sickle cell confers advantage in resistance to malaria while homozygocity causes sickle cell disease.

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Certain cancers (I believe Ras-linked cancers?) Potentially experience this actually.

I think it was an in vitro study where overactive Ras was studied in homozygous WT, heterozygous, and homozygous mutant, while growth of cell populations was observed. They actually found that heterozygous conditions exhibited more severe progression of the disease.

It's thought that certain cancerous signals operate within a sweet spot, where their results are not so severe that feedback mechanisms halt them, but are severe enough to cause a diseased phenotype.

I'll take another look at my notes and double check the details of this because it was really a quite fascinating example of this exact phenomenon you're asking about.

If you're interested as to why - Ras at normal levels induces normal proliferation. Certain mutations to Ras are able to push this into excessive proliferation. However beyond this, even more proliferative signaling through Ras induces senescence instead and causes cells to age and effectively die. Hence there is a 'sweet spot' possible where some mutant Ras is present but the signaling is not so excessive that cancer cells die.

EDIT: After going to my notes to check it was in fact mutation of Ras which alters it's nucleotide binding such that it is constitutively active.

If you want to read more about it, the paper describes it as the 'sweet spot' model here: https://www.nature.com/articles/s41568-018-0076-6

It seems there is some nuance to do with the signaling power of given mutations which might contribute to oncogenesis as well, so perhaps not a perfect model of heterozygosity being more pathogenic than homozygosity, however the concept is still somewhat there I think.

This is why r/AskScience doesn’t allow AI-generated answers, and bans people who provide them.

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Ebola (or ebola hemorrhagic fever) is a zoonotic viral disease which has resurfaced multiple times in separate "spillover" events from its animal reservoir species, which likely includes bats and nonhuman primates. There's more than one ebolavirus, and multiple strains have been implicated in outbreaks, with the Zaire ebolavirus thus far being the most deadly.

Even though ebola can be transmitted from one human to another, humans are not a reservoir species for ebolavirus due to the fact that it a) does not remain indefinitely latent in the human body b) is relatively hard to transmit in that it requires direct physical exposure to infected material and c) it is very frequently fatal. This is why outbreaks have been relatively sporadic with no global spread.

Your post mentioned overdominance, which made me look up the term on Wikipedia.

That led me to the article for underdominance: https://en.wikipedia.org/wiki/Underdominance

This made me wonder, does one of the examples on that page fit the OP's question?

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Depends on where the age cutoff is. Some of those have a greatly reduced life expectancy. At 40 years of age the heterocygotic people have more symptoms compared to the dead ones.

Don't trust the AIs further than you can throw them.

A bit indirect, but some forms of achondroplasia are so severe that homozygotes are incompatible with live birth, and thus heterozygous (or homozygous would type) are the only observed.

A better example: ABO blood types in terms of blood contaminagion (whether available acceptable blood types, or maternal-fetal hemolytic anemia). Diversity of heterozygous actually works against a “phenotype” of immune acceptance.

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Completely wrong and useless answer in this context. Almost certain this is assuming the homozygous has two normal alleles, which isn’t what OP was asking.

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