> And the good old "correlation is not causation" adage applies for #3 and #4.
It does, but it's not hard to come up with plausible causes for the correlation to support in those cases.
It is probably more accurate to say "Academic aptitutde correlates with job stability which correlates with lower overall stress levels which is part of the definition for better health which correlates with longevity."
1. Month of birth directly determines a child's age compared to their classmates.
2. An older child among younger peers performs better academically.
3. Academic aptitude is correlated with income.
4. Income is correlated with longevity.
Admittedly, hypothesis #2 is iffy. And the good old "correlation is not causation" adage applies for #3 and #4.