6 ms·

I realize that this probably wouldn't fit in the title, but this is about a specific kind of adult stem cell, not stem cells in general. It's trivially obvious

I realize that this probably wouldn't fit in the title, but this is about a specific kind of adult stem cell, not stem cells in general. It's trivially obvious that some kinds of stem cell can become any type of cell, given that we all had our beginnings as a single cell.

CodeWriter23 2y ago
> It's trivially obvious that some kinds of stem cell can become any type of cell, given that we all had our beginnings as a single cell. It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. For example at 4-5 years of age being able to speak different phonenes is lost due to mass die off of a certain type of brain cell. Could be the same for the pair of cells that start a human life. Once their purpose is served they may never exist again.
- rf15 2y ago
  Do you have a source on the phonemes situation? First time I hear of it, and I'm pretty sure I've seen people learn them past that point. I know they struggle with it, but, as an example, even japanese people can learn the effective difference between l and r given enough effort.
  - CodeWriter23 2y ago
    It’s why certain ethnicities cannot pronounce words in their non-native language. Like people from the US not being able to make certain consonant sounds in German or Chinese being unable to pronounce the R consonant. So go look it up yourself.
- Turing_Machine 2y ago
  > It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. I'm not sure what difference that would make. Those brain cells (and all the other brain cells that don't die off) were still formed by successive divisions of the single cell that resulted from sperm meeting egg. Therefore, that original cell is capable of producing any cell type found in the body.
  - CodeWriter23 2y ago
    By your logic, every cell in the human body is a brain cell.
- burning_hamster 2y ago
  You are referring to the critical period [1] of (second) language acquisition, which is generally thought to end with the onset of puberty [2]. Neurodevelopmentally, this period coincides with extensive synaptic and dendritic pruning and increased myelination (of axons) [3], which result in the loss of some connections and the strengthening and acceleration of others. Cell loss is not thought to be a major driver of brain maturation, nor is it thought to occur more frequently during this time window. [1] https://en.wikipedia.org/wiki/Critical_period_hypothesis https://en.wikipedia.org/wiki/Critical_period_hypothesis [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857581/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857581/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982854/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982854/

CodeWriter23 2y ago

> It's trivially obvious that some kinds of stem cell can become any type of cell, given that we all had our beginnings as a single cell. It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. For example at 4-5 years of age being able to speak different phonenes is lost due to mass die off of a certain type of brain cell. Could be the same for the pair of cells that start a human life. Once their purpose is served they may never exist again.

rf15 2y ago
Do you have a source on the phonemes situation? First time I hear of it, and I'm pretty sure I've seen people learn them past that point. I know they struggle with it, but, as an example, even japanese people can learn the effective difference between l and r given enough effort.
- CodeWriter23 2y ago
  It’s why certain ethnicities cannot pronounce words in their non-native language. Like people from the US not being able to make certain consonant sounds in German or Chinese being unable to pronounce the R consonant. So go look it up yourself.
Turing_Machine 2y ago
> It’s not that obvious, as the brain grows, certain kind of cells die off and never come back. I'm not sure what difference that would make. Those brain cells (and all the other brain cells that don't die off) were still formed by successive divisions of the single cell that resulted from sperm meeting egg. Therefore, that original cell is capable of producing any cell type found in the body.
- CodeWriter23 2y ago
  By your logic, every cell in the human body is a brain cell.
burning_hamster 2y ago
You are referring to the critical period [1] of (second) language acquisition, which is generally thought to end with the onset of puberty [2]. Neurodevelopmentally, this period coincides with extensive synaptic and dendritic pruning and increased myelination (of axons) [3], which result in the loss of some connections and the strengthening and acceleration of others. Cell loss is not thought to be a major driver of brain maturation, nor is it thought to occur more frequently during this time window. [1] https://en.wikipedia.org/wiki/Critical_period_hypothesis https://en.wikipedia.org/wiki/Critical_period_hypothesis [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857581/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857581/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982854/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982854/