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I think immortal is the wrong word here. All organisms die. If it's not aging, then decease and predators will do it.
I'm not aware of a context where immortal refers to organisms that can't be killed by accidents and predators. In mythology and novels alike, vampires, gods, elves, ..., are all called immortal and still can be killed.
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I think immortal is the wrong word here. All organisms die. If it's not aging, then decease and predators will do it.
Biological immortality is the technical term for organisms which do not die unless killed, or more accurately where rate of mortality from senescence does not increase with chronological age.
This reminds me of Lynn Margulis’ discovery that mitochondria and chloroplasts are ancient bacteria incorporated into the cell [2].
[1] https://en.wikipedia.org/wiki/Syncytin-1
[2] https://en.wikipedia.org/wiki/Lynn_Margulis#Endosymbiosis_th...
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Sorry for asking a simple question, but how do we distinguish sexes? If male seahorses can be pregnant, it's obviously not by which sex gives birth.
It’s entirely determined by the gametes. Males produce sperm, females produce eggs.
Edit: Looks like it's merely relative size, and when neither gamete is bigger biologists throw up their hands. Sort of a bummer that there isn't a more robust definition.
Every thing about life is so fascinating. I have always wondered how viruses have persisted for so long if they need a host to survive and it took us millions of years to go from single celled to multicellular. I wish there was a way to know everything and become good at everything. :/
> I wish there was a way to know everything and become good at everything. There must be some way to do it, because I constantly encounter people on the Internet, that know everything, and are good at everything. I can’t get any of them to tell me how they do it, though...
Magnificent. The placenta uses a protein named syncytin [1] to attach to the cells of the uterus. This protein is expressed by a retrovirus that was integrated into animal DNA over 100 million years ago. This reminds me of Lynn Margulis’ discovery that mitochondria and chloroplasts are ancient bacteria incorporated into the cell [2]. [1] https://en.wikipedia.org/wiki/Syncytin-1 [2] https://en.wikipedia.org/wiki/Lynn_…
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It’s entirely determined by the gametes. Males produce sperm, females produce eggs.
And the thing that distinguishes eggs from sperm is what? The relative size? (Are there no species where they are roughly the same?) Or that the mitochondria come from the egg? Edit: Looks like it's merely relative size, and when neither gamete is bigger biologists throw up their hands. Sort of a bummer that there isn't a more robust definition. https://en.wikipedia.org/wiki/Isogamy
Also note that sperm vary in shape. Mammalian sperm have the familiar tadpole shape with a flagellum for swimming. Other species, such as nematodes, have ameboid sperm which move along surfaces rather than swimming freely.
It is also being researched how endogenous retroviruses are part of aging. The very rough idea being that at some point long in past a retrovirus became endogenous and provided a pathway for aging increasing the evolutionary rate of that organism, which would then out-compete most of the immortal organisms with time. Something like: https://pubmed.ncbi.nlm.nih.gov/20346965/