Recent comments in /f/askscience

remimorin t1_j5k9j0s wrote

Reply to why do we not see the reappearance of extinct lifeforms anymore if evolution can retrace its step to redevelop it? by 0011000l

People have already answered. I would like to add, see convergent evolution. Same évolutive pressure results in similar response (results). But similar is important not the same. As there never have been 2 deck of cards shuffled identically (given they were well shuffled), you will never get exactly the same thing.

How similar things can be? See barracuda and muskellunge, carcinization to begin with! Thyalcine and canids.

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amarillion97 t1_j5k27pd wrote

Reply to why do we not see the reappearance of extinct lifeforms anymore if evolution can retrace its step to redevelop it? by 0011000l

The amount of random chance involved means that it is practically impossible.

Besides that, the course of evolution of one species is influenced by species in the surrounding ecosystem. Symbionts, competitors, parasites, diseases etc. that were present when C evolved to D all have an influence. But those species have also evolved in the mean time. The exact same conditions will never arise again.

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nervouscomposure t1_j5jy9oq wrote

Reply to comment by Quiz_Quizzical-Test_ in What is a neurotransmitter "turnover rate", with reference to acetylcholine? What does it mean if the turnover rate is increased or decreased? by yungPH

Very interesting, thanks for the pharmaceutical explanation. I take a cholinergic drug to treat Myasthenia Gravis, a disease caused directly by acetylcholine binding issues, so my ears perk up anytime I see the little molecule mentioned. For me, the decreased turnover means better voluntary muscle function

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BirdLawyerPerson t1_j5jqppg wrote

Reply to comment by Bax_Cadarn in What is a neurotransmitter "turnover rate", with reference to acetylcholine? What does it mean if the turnover rate is increased or decreased? by yungPH

Any acronym related to illness, disease, or medical issues, I just assume come from medical students trying to cram for exams. The sheer amount of lists they have to memorize makes acronyms a pretty good memorization technique.

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Thugluvdoc t1_j5jpqfg wrote

Reply to What is a neurotransmitter "turnover rate", with reference to acetylcholine? What does it mean if the turnover rate is increased or decreased? by yungPH

Think of neurotransmitters (NT) as a person, and the synapse/neuron as a button. Imagine there are a group of people whose job is to press the buttons (stimulate the neurons) as many times and as often as possible but they get tired and leave. So turnover rate means how often the person gets tired and leaves the button alone. SSRIs do not allow serotonin to be “reuptaken” or in this example, the person in the room pushing buttons isn’t allowed to leave so he’s constantly pushing the buttons (stimulating the receptor). That’s a basic overview. Obviously overstimulation means your body down regulates the receptor (less buttons to push), and the opposite happens when you take something away from the body - your body upregulates the receptor - puts more buttons hoping to find a neurotransmitter (person) to stimulate it (push the button). Sorry if this sucks, hope it helps.

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thebedla t1_j5jjlho wrote

Reply to why do we not see the reappearance of extinct lifeforms anymore if evolution can retrace its step to redevelop it? by 0011000l

This has been observed, it's called iterative evolution or Lazarus taxon or Elvis taxon.

Note the rationale behind renaming Lazarus to Elvis is to allude to impersonators and clarify that it is not actually being reborn. Given how much genetic information there is, superficially "the same" species (such as the "re-evolved Aldabra rail) will still be different genetically.

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