ЁЯЪиNew paper on "Psychology as a historical science" w/ @JoHenrich & @slingerland20 in Annual Review of Psychology. Catalyzing the field of "historical psychology" by reviewing work on: origins of psychology and institutions today, psychology of the past (data from dead minds) 1/
Jump starting a new field: Historical Psychology. Pop the clutch... @slingerland20 @mmuthukrishna @RachelASpicer https://t.co/0J30gbFRYA pic.twitter.com/GB0Pyj8t7T
— Joe Henrich (@JoHenrich) January 3, 2021
More from Health
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Why do B12 and folate deficiencies lead to HUGE red blood cells?
And, if the issue is DNA synthesis, why are red blood cells (which don't have DNA) the key cell line affected?
For answers, we'll have to go back a few billion years.
2/
RNA came first. Then, ~3-4 billion years ago, DNA emerged.
Among their differences:
ЁЯФ╣RNA contains uracil
ЁЯФ╣DNA contains thymine
But why does DNA contains thymine (T) instead of uracil (U)?
https://t.co/XlxT6cLLXg
3/
ЁЯФСCytosine (C) can undergo spontaneous deamination to uracil (U).
In the RNA world, this meant that U could appear intensionally or unintentionally. This is clearly problematic. How can you repair RNA when you can't tell if something is an error?
https://t.co/bIZGviHBUc
4/
DNA's use of T instead of U means that spontaneous C тЖТ U deamination can be corrected without worry that an intentional U is being removed.
DNA requires greater stability than RNA so the transition to a thymine-based structure was beneficial.
https://t.co/bIZGviHBUc
5/
Let's return to megaloblastic anemia secondary to B12 or folate deficiency.
When either is severely deficient deoxythymidine monophosphate (dTMP*) production is hindered. With less dTMP, DNA synthesis is abnormal.
[*Note: thymine is the base in dTMP]
https://t.co/AnDUtKkbZh
Why do B12 and folate deficiencies lead to HUGE red blood cells?
And, if the issue is DNA synthesis, why are red blood cells (which don't have DNA) the key cell line affected?
For answers, we'll have to go back a few billion years.
2/
RNA came first. Then, ~3-4 billion years ago, DNA emerged.
Among their differences:
ЁЯФ╣RNA contains uracil
ЁЯФ╣DNA contains thymine
But why does DNA contains thymine (T) instead of uracil (U)?
https://t.co/XlxT6cLLXg
3/
ЁЯФСCytosine (C) can undergo spontaneous deamination to uracil (U).
In the RNA world, this meant that U could appear intensionally or unintentionally. This is clearly problematic. How can you repair RNA when you can't tell if something is an error?
https://t.co/bIZGviHBUc
4/
DNA's use of T instead of U means that spontaneous C тЖТ U deamination can be corrected without worry that an intentional U is being removed.
DNA requires greater stability than RNA so the transition to a thymine-based structure was beneficial.
https://t.co/bIZGviHBUc
5/
Let's return to megaloblastic anemia secondary to B12 or folate deficiency.
When either is severely deficient deoxythymidine monophosphate (dTMP*) production is hindered. With less dTMP, DNA synthesis is abnormal.
[*Note: thymine is the base in dTMP]
https://t.co/AnDUtKkbZh
You gotta think about this one carefully!
Imagine you go to the doctor and get tested for a rare disease (only 1 in 10,000 people get it.)
The test is 99% effective in detecting both sick and healthy people.
Your test comes back positive.
Are you really sick? Explain below ЁЯСЗ
The most complete answer from every reply so far is from Dr. Lena. Thanks for taking the time and going through
You can get the answer using Bayes' theorem, but let's try to come up with it in a different тАФmaybe more intuitiveтАФ way.
ЁЯСЗ
Here is what we know:
- Out of 10,000 people, 1 is sick
- Out of 100 sick people, 99 test positive
- Out of 100 healthy people, 99 test negative
Assuming 1 million people take the test (including you):
- 100 of them are sick
- 999,900 of them are healthy
ЁЯСЗ
Let's now test both groups, starting with the 100 people sick:
тЦля╕П 99 of them will be diagnosed (correctly) as sick (99%)
тЦля╕П 1 of them is going to be diagnosed (incorrectly) as healthy (1%)
ЁЯСЗ
Imagine you go to the doctor and get tested for a rare disease (only 1 in 10,000 people get it.)
The test is 99% effective in detecting both sick and healthy people.
Your test comes back positive.
Are you really sick? Explain below ЁЯСЗ
The most complete answer from every reply so far is from Dr. Lena. Thanks for taking the time and going through
Really doesn\u2019t fit well in a tweet. pic.twitter.com/xN0pAyniFS
— Dr. Lena Sugar \U0001f3f3\ufe0f\u200d\U0001f308\U0001f1ea\U0001f1fa\U0001f1ef\U0001f1f5 (@_jvs) February 18, 2021
You can get the answer using Bayes' theorem, but let's try to come up with it in a different тАФmaybe more intuitiveтАФ way.
ЁЯСЗ
Here is what we know:
- Out of 10,000 people, 1 is sick
- Out of 100 sick people, 99 test positive
- Out of 100 healthy people, 99 test negative
Assuming 1 million people take the test (including you):
- 100 of them are sick
- 999,900 of them are healthy
ЁЯСЗ
Let's now test both groups, starting with the 100 people sick:
тЦля╕П 99 of them will be diagnosed (correctly) as sick (99%)
тЦля╕П 1 of them is going to be diagnosed (incorrectly) as healthy (1%)
ЁЯСЗ
