They are using this approach or a very similar one to try to find LUCA ( the lasts universal common ancestor). Not necessarily the first living thing but the oldest living thing that all current organisms can trace their lineages back to.

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The earliest evolutionary organism would have to be a single molecule (probably RNA) able to reproduce itself with potential mistakes in a very specific environment (probably rich in organic molecules) that happened to be common enough at the time this organism appeared.

Anything with multiple molecules would most likely be too complex to appear first without previous evolution to learn to make those molecules and a container.

Because we don't know what was this early environment (there's some hypothesis, but no clear answer), we can't test what was the smallest RNA possible.

See https://en.wikipedia.org/wiki/Sex-determining_region_Y_protein and https://en.wikipedia.org/wiki/Y_chromosome#Human_Y_chromosome

Most genes involved in male sexual characters are on other chromosomes but require a cascade initiated by expression of SRY (thus presence of Y chromosome) to be (un)expressed

I see, thank you!

Probably not. The last universal common ancestor (LUCA) of all life, circa 3.6 billion years ago, was bacteria-like and most likely to be free living (or somewhat colony forming). It's unlikely that a free living organism could have a genome as small as 438 genes. We also know that most major protein structural families data back to that period so a fairly complete repertoire of possible biochemical functions would have been within evolutionary reach to the LUCA. So it seems likely the LUCA was quite sophisticated from a biochemical function POV. We see that contemporary bacterial genomes tend to favour minimum levels of redundancy but that isn't the same as having smaller numbers of genes. Different types of bacterial genomes have very diverse counts of the number of genes present. Between these observations there's little reason to suspect that the LUCA's genome was minimal.

Anything older than the LUCA, such as pro-genotes (things before "modern" genomes appeared) or even earlier forms would have been substantially different to an organism with an organised genome of 438 genes. The further back in time you go towards the abiotic origin of life the more "weird" and less cellular early life probably was. There remains a reasonable chance that the earliest self replicating systems were just soups of nucleotide chains, which would arguably be the earliest life-like things on earth (circa 4.6 bya), and that's quite unlike a genome-containing cellular organism.

It remains a very open question what the earliest self-replicators that gave rise to cells might have been but all the options are pretty weird. Here's a somewhat decent summary of some models

https://www.bionity.com/en/encyclopedia/Origin_of_life.html

I know one of the smallest genomes is for HEP D, its a satellite virus that only has like 3 genes. It uses the proteins from Hep A-C because it doesn't have them all. So to get D, you have to have another HEP. Pretty cool, honestly. It only has 1700 bp and is thought to maybe be a old plant virus called a viroid

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Y chromosome is smaller because it doesn't really contain as much genetic information as the X chromosome does.

X chromosome container several vital genetic information but Y has mostly genetic codes that are often redundant or obsolete and overridden by X except sexual development.

There are some animals like whiptail lizard which only have females because as they evolved their male allosome (the human equivalent of Y chromosome) became redundant and unnecessary.

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The vast majority of Antarctica's ice is above sea level, and its average thickness is over is above 2 km: https://en.m.wikipedia.org/wiki/Antarctic_ice_sheet

That's a lot of water that is currently above the ocean, that would be added to the ocean.

To sort of echo the other response in a different way, I find it easier to think of early life in a chemistry sense rather than a biology sense. Chemical reactions can "reproduce"(autocatalysis), and they can compete with other reactions over the starting ingredients for the reaction. We can get these sort of lifelike qualities from very simple structures that could be outcompeted by more complex and better replicating structures over time. If you're interested in more about origin of life research, I found that the YouTube channel "Professor Dave Explains" does a really good job of giving easy enough to understand explanations for stuff like this.

FFI is caused by a mutation in the PrP gene that predisposes it to misfolding causing disease. If this DNA mutation is not passed down to the fetus, then it won't get the disease even if the mother has FFI. The misfolded protein itself will not be passed from mother to fetus.

www.science.org/doi/abs/10.1126/science.1439789

Not sure if this helps, but I recently learned about viroids in my bio classes. From what I've gathered, viroids are basically just sequences of genetic material that can have virus-like effects. Most viroids don't have a shell (Envelope or capsid) like most viruses do, and they have far fewer genes. I believe that most viroids consists of just a few hundred base pairs. What's intriguing to me is that viroids don't actually code for anything. I think maybe some viroids code for one protein, but that's about it. Despite this, viroids can still wreak havoc on an organism. It's difficult to determine whether or not viroids are living things or organisms, but I think there is definitely some function there as you put it.

I find the concept of prions to be useful in understanding this. Ofc, prions are complex proteins and massively more complex and durable than any early life-precursor would have been, but they can fold other proteins into copies of themselves. Early protoliving assemblages could have been amino acid assemblages that generally tend to replicate through a few stages, and more effective/ more complicated versions of them were able to keep replicating and working together until eventually they could form something that would be considered living.

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The chemosynthesis guys are considered primary producers also. Right?

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Well first we must distinguish between “non-coding” and the pop-science concept of “junk” DNA. While the most interesting thing about DNA is its ability to code for genes, that is not the only thing it does.

Most of our DNA has some kind of function. That could be coding for RNA that isn’t supposed to be transcribed. It could be structural, like telomeres and centromeres. It could be about regulating transcription or replication.

All the same, human DNA is much more prone to accumulating dead genes than bacterial DNA due to our generation time. We can carry around a bunch of pseudogenes or ancient viruses that managed to get themselves added to our genome. Selection pressure is much less and much slower when it takes 20-40 years to reproduce as opposed to 20-40 minutes.

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No.

First and foremost, this ignores that in calculating hypothetical sea level rise from complete melting of the Antarctic ice sheet, ice below sea level is already removed from consideration. This is explained relatively well on this page that goes through the calculation of sea level rise equivalence. So, the value of ~60 meters of sea level rise that would result from melting of the Antarctic reflects the volume of ice (converted to water and spread over the ocean surface) above sea level.

Secondly, if anything this value represents an underestimate because it does not account for isostatic rebound. In short, as the ice melts, the land underneath the ice will rise up in response to the reduction of mass above it. As such, we would expect that as ice melted, the ground surface would elevate in response and thus a good portion of the ice that is currently below sea level (because the ground has subsided) and which is not factored into the calculuation, would actually contribute to sea level rise because it would no longer be below sea level when it melted. For a more thorough discussion of what Antarctica without ice might look like, you can check out this previous thread.

Finally, the sea level rise equivalents are pretty much only dealing with mass and not considering the steric components of sea level rise (i.e., the changes in sea level rise due to changes in density related to either temperature or salinity). Melting all of Antarctica would have a complicated effect in this regard. It would directly reduce density (and thus reflect expansion, so more sea level rise) through freshening, but adding all of that cold water could temporarily reduce temperature (at least regionally) increasing density (and thus reflect contraction, so less sea level rise). Presumably though, to be able to melt all of Antarctica would reflect relatively high average air and ocean temperatures, so this cooling would likely be temporary so you would have to also account for potential thermal expansion after all that melt water had a chance to heat up to whatever the average ocean temperature was at this hypothetical time.

as to the second part, there has been a lot of speculation on the possibility of a humanzee, human/chimp hybrid because our chromosome count differs by one, just like horses and donkeys.

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