6 ms·

Lifespan depends on month of birth (2000)

116 points by Petiver 12y ago

reasonattlm 12y ago
Leonid Gavrilov and Natalia Gavrilova are a good resource for this sort of demography and epidemiology of aging. [1] In particular they have a lot of material on season of birth effects. [2] Tangentially related to the seasonal effects is data suggesting that solar cycles also influence longevity, possibly through quite indirect responses to levels of UV exposure in pregnant women. [3] You can see how this might be relevant to season as well, but it is only one of a number of mechanistic theories on the subject. This sort of thing ties back in to application of reliability theory to aging [4], wherein to make the models fit the observed data individuals have to be born with a preexisting non-zero damage load. [1]: http://longevity-science.org/ http://longevity-science.org/ [2]: http://longevity-science.org/Season-of-Birth.pdf http://longevity-science.org/Season-of-Birth.pdf [3]: http://rspb.royalsocietypublishing.org/content/282/1801/20142032 http://rspb.royalsocietypublishing.org/content/282/1801/2014... [4]: https://en.wikipedia.org/wiki/Reliability_theory_of_aging_and_longevity https://en.wikipedia.org/wiki/Reliability_theory_of_aging_an...
- ekianjo 12y ago
  But the data in the post does not seem to be super correlated to seasons. You can see that the decrease in life expectancy occurs way before spring (as soon as February) which is still supposed to be a winter month. So the season link is weak.
  - vlasev 12y ago
    I'm thinking it has to do with the continuous day/night cycle. It'll be interesting to see if there are any changes with latitude, in particular, what happens in countries closer to the equator.
    - ekianjo 12y ago
      But is there any rationale behind that anyway ? Do we see people born during summer being usually in poorer health than people born during November-December, let's say ?
- jrapdx3 12y ago
  The differential exposure to UVB, that is, sunlight, was the first thing I thought of reading this article. It is especially likely among people born in the industrial-era 19th century, at a time before the nature of the link between health and sunlight was clearly identified. Around a hundred years ago, the role of UV in preventing rickets was confirmed. By the 1930's, vitamin D supplementation of foods became widespread, and the most obvious manifestations of deficiency (e.g., rickets) essentially disappeared. Studied intensively since the 1930's numerous effects of D (or lack of it) have been reported, and recently interest has exploded. Increasingly evidence implicates low vitamin D levels in a wide range of conditions, such as autoimmune disorders, cancer, and metabolic disease, that are likely contributors to reduction of life expectancy. Seasonality of vitamin D level is well known. In northern latitudes (>=45th parallel) the nadir occurs around March-April, and the peak is measured on average in September-October. The timing of these fluctuations appears quite congruent with the article's assertions about life expectancy, so it's reasonable to think there is a connection. For anyone interested in vitamin D, I highly recommend this excellent review: http://www.tandfonline.com/doi/full/10.4161/derm.24494 http://www.tandfonline.com/doi/full/10.4161/derm.24494
jcampbell1 12y ago
This is interesting. They seem to think it is in utero effect. Maybe Vitamin D? I wondered if they considered if the cause is age when starting school. I know that birth month has pretty powerful effects for educational attainment.
- sillysaurus3 12y ago
  What month should I conceive my child to maximize their educational attainment? I'm only half joking.
  - jcampbell1 12y ago
    Depends on the rules which vary by location, but you want your kid to be the oldest in the class. Your older kid is going to believe she is very bright in 1st grade, and have a lifetime of confidence to achieve great things. The real reason she was such a good student in 1st grade is because she was just older.
    - ekianjo 12y ago
      > The real reason she was such a good student in 1st grade is because she was just older. That may be an intuitive reasoning but not sure it holds true. I have seen numerous times the youngest students performing actually better in class than older ones. Do you have hard data to support this ?
      - jedberg 12y ago
        I have no hard data, but I have 10 years of anecdotal data (my wife was a 4th grade teacher for ten years and saw just about 1000 students over her career). She says the younger kids definitely do worse by all measures in 4th grade, in large part because of their lack of maturity.
        ekianjo 12y ago
        > in large part because of their lack of maturity. Maybe that depends on the topic you are teaching then ?
arjie 12y ago
Very curious. Information about people in the tropics would be interesting since climate doesn't vary as much there. I know in Madras, India it was hot pretty much all of the time, except when it rained.
joe_the_user 12y ago
The correlation is in terms of fractions of a year so they add up to an average of plus-or-minus a few month over a lifetime. The three curves don't seem to have a very close relationship to each other though there are some similarities. I assume that if they are getting a meaningful correlation, it is over a large amount of data. It seems logical that at large scale, date born would correlate with a variety of things in various areas - social class and wealth come to mind. I think it's a matter of taste whether one says "wow, throw enough data together you find unexpected correlations" or "garbage in, garbage out". A life insurance company could eek out a bit of profit changing its price structure on this data - if it didn't have far more to lose if the use of such tactics became public. I bet someone can use this to claim astrology has validity too.
- mbq 12y ago
  Also this is only about three countries selected a priori, so not a really good sample, even if the number of individuals is huge...
deleted 12y ago
[deleted]
EGreg 12y ago
It could also have something to do with their development in school. After all the school year is the same for all. Some kids are up to 11 months younger!
- danielbarla 12y ago
  This is an area which I've personally experienced, having spent the first half of my school years in Europe, and being a few days shy of the cut-off point for being held back another year, I was always the youngest in my class (I guess on a large enough population, it would mean that similar kids are the smallest as well, on average). Later on I switched to a southern-hemisphere school, which was out of phase by 6 months, and I was all of a sudden roughly average age in class. Not that it had a huge impact on me, but it was noticeable, which probably means it has some effect on average.
- TorKlingberg 12y ago
  The effect of school could be isolated by comparing different countries with different cutoff dates. I believe the American and UK systems are based on age when the school year starts, so the youngest in the class were born in August. Sweden groups classes by birth year, so the youngest were born in December. The Japanese school year starts in spring.
shele 12y ago
"The differences in lifespan are independent of the seasonal distribution of deaths" That's important of course.
randyrand 12y ago
Or maybe death on the month?
- amelius 12y ago
  Indeed. If most deaths occur during mid-summer, then people born in autumn live slightly longer on average than people born in spring.
dmichulke 12y ago
I didn't fully read it but doesn't it look like there is potentially a big survivorship bias in the data? They touch the subject with their 3rd hypothesis but in general it's possible that you still have a higher life expectancy being born from April-June in the Northern Hemisphere because you have increased chances of reaching 50. So why this limit of 50 years? What is the expected lifespan for newborns depending on their month of birth?
awjr 12y ago
Would be interesting to look at the 'stresses' that occur within schools. My 11 year old daughter was born on the 30th of August. Ergo she is the youngest in the year at school. She is studying with people that have a year of development on her. She is doing fantastically well but works hard to achieve that result. My hypothesis is that the age cut off in schools, unduly puts stress on the younger children in a class, that long term, impact on health in later years. In effect which month you are born in affects the stress you will feel during your school years as it will be inherently 'harder' for you.
- beaumartinez 12y ago
  I'd think the opposite. Since she is used to having to work hard from a young age, she will be more successful in life. Others who coasted through—whom were used to everything being relatively easier—will not have the experience she has already accrued when faced with a harder challenge.
  - awjr 12y ago
    Not sure that makes sense. She potentially experiences 12 years of increased stress compared to her peers. I'm not implying that later in life, she will have better tools for work, but that her body would have spent most of her formative years under more stress. This would then reflect in a shorter lifespan. Note however that this concept she would gain the tools for hard working in itself is flawed. Studies have shown that those born in the Summer months have statistically lower exam scores.
    - theklub 12y ago
      If stress from school caused people to die earlier I think we'd know by now.
      - vidarh 12y ago
        How would we know? Why?
      - 12y ago
FranOntanaya 12y ago
I would think people conceived in warm weather are more likely to be from less stable relationships...

116 points by Petiver 12y ago

Leonid Gavrilov and Natalia Gavrilova are a good resource for this sort of demography and epidemiology of aging. [1] In particular they have a lot of material on season of birth effects. [2] Tangentially related to the seasonal effects is data suggesting that solar cycles also influence longevity, possibly through quite indirect responses to levels of UV exposure in pregnant women. [3] You can see how this might be relevant to season as well, but it is only one of a number of mechanistic theories on the subject. This sort of thing ties back in to application of reliability theory to aging [4], wherein to make the models fit the observed data individuals have to be born with a preexisting non-zero damage load. [1]: http://longevity-science.org/ http://longevity-science.org/ [2]: http://longevity-science.org/Season-of-Birth.pdf http://longevity-science.org/Season-of-Birth.pdf [3]: http://rspb.royalsocietypublishing.org/content/282/1801/20142032 http://rspb.royalsocietypublishing.org/content/282/1801/2014... [4]: https://en.wikipedia.org/wiki/Reliability_theory_of_aging_and_longevity https://en.wikipedia.org/wiki/Reliability_theory_of_aging_an...

ekianjo 12y ago
But the data in the post does not seem to be super correlated to seasons. You can see that the decrease in life expectancy occurs way before spring (as soon as February) which is still supposed to be a winter month. So the season link is weak.
- vlasev 12y ago
  I'm thinking it has to do with the continuous day/night cycle. It'll be interesting to see if there are any changes with latitude, in particular, what happens in countries closer to the equator.
  - ekianjo 12y ago
    But is there any rationale behind that anyway ? Do we see people born during summer being usually in poorer health than people born during November-December, let's say ?
jrapdx3 12y ago
The differential exposure to UVB, that is, sunlight, was the first thing I thought of reading this article. It is especially likely among people born in the industrial-era 19th century, at a time before the nature of the link between health and sunlight was clearly identified. Around a hundred years ago, the role of UV in preventing rickets was confirmed. By the 1930's, vitamin D supplementation of foods became widespread, and the most obvious manifestations of deficiency (e.g., rickets) essentially disappeared. Studied intensively since the 1930's numerous effects of D (or lack of it) have been reported, and recently interest has exploded. Increasingly evidence implicates low vitamin D levels in a wide range of conditions, such as autoimmune disorders, cancer, and metabolic disease, that are likely contributors to reduction of life expectancy. Seasonality of vitamin D level is well known. In northern latitudes (>=45th parallel) the nadir occurs around March-April, and the peak is measured on average in September-October. The timing of these fluctuations appears quite congruent with the article's assertions about life expectancy, so it's reasonable to think there is a connection. For anyone interested in vitamin D, I highly recommend this excellent review: http://www.tandfonline.com/doi/full/10.4161/derm.24494 http://www.tandfonline.com/doi/full/10.4161/derm.24494

jcampbell1 12y ago

This is interesting. They seem to think it is in utero effect. Maybe Vitamin D? I wondered if they considered if the cause is age when starting school. I know that birth month has pretty powerful effects for educational attainment.

sillysaurus3 12y ago
What month should I conceive my child to maximize their educational attainment? I'm only half joking.
- jcampbell1 12y ago
  Depends on the rules which vary by location, but you want your kid to be the oldest in the class. Your older kid is going to believe she is very bright in 1st grade, and have a lifetime of confidence to achieve great things. The real reason she was such a good student in 1st grade is because she was just older.
  - ekianjo 12y ago
    > The real reason she was such a good student in 1st grade is because she was just older. That may be an intuitive reasoning but not sure it holds true. I have seen numerous times the youngest students performing actually better in class than older ones. Do you have hard data to support this ?
    - jedberg 12y ago
      I have no hard data, but I have 10 years of anecdotal data (my wife was a 4th grade teacher for ten years and saw just about 1000 students over her career). She says the younger kids definitely do worse by all measures in 4th grade, in large part because of their lack of maturity.
      - ekianjo 12y ago
        > in large part because of their lack of maturity. Maybe that depends on the topic you are teaching then ?

arjie 12y ago

Very curious. Information about people in the tropics would be interesting since climate doesn't vary as much there. I know in Madras, India it was hot pretty much all of the time, except when it rained.

joe_the_user 12y ago

The correlation is in terms of fractions of a year so they add up to an average of plus-or-minus a few month over a lifetime. The three curves don't seem to have a very close relationship to each other though there are some similarities. I assume that if they are getting a meaningful correlation, it is over a large amount of data. It seems logical that at large scale, date born would correlate with a variety of things in various areas - social class and wealth come to mind. I think it's a matter of taste whether one says "wow, throw enough data together you find unexpected correlations" or "garbage in, garbage out". A life insurance company could eek out a bit of profit changing its price structure on this data - if it didn't have far more to lose if the use of such tactics became public. I bet someone can use this to claim astrology has validity too.

mbq 12y ago
Also this is only about three countries selected a priori, so not a really good sample, even if the number of individuals is huge...

deleted 12y ago

[deleted]

EGreg 12y ago

It could also have something to do with their development in school. After all the school year is the same for all. Some kids are up to 11 months younger!

danielbarla 12y ago
This is an area which I've personally experienced, having spent the first half of my school years in Europe, and being a few days shy of the cut-off point for being held back another year, I was always the youngest in my class (I guess on a large enough population, it would mean that similar kids are the smallest as well, on average). Later on I switched to a southern-hemisphere school, which was out of phase by 6 months, and I was all of a sudden roughly average age in class. Not that it had a huge impact on me, but it was noticeable, which probably means it has some effect on average.
TorKlingberg 12y ago
The effect of school could be isolated by comparing different countries with different cutoff dates. I believe the American and UK systems are based on age when the school year starts, so the youngest in the class were born in August. Sweden groups classes by birth year, so the youngest were born in December. The Japanese school year starts in spring.

shele 12y ago

"The differences in lifespan are independent of the seasonal distribution of deaths" That's important of course.

randyrand 12y ago

Or maybe death on the month?

amelius 12y ago
Indeed. If most deaths occur during mid-summer, then people born in autumn live slightly longer on average than people born in spring.

dmichulke 12y ago

I didn't fully read it but doesn't it look like there is potentially a big survivorship bias in the data? They touch the subject with their 3rd hypothesis but in general it's possible that you still have a higher life expectancy being born from April-June in the Northern Hemisphere because you have increased chances of reaching 50. So why this limit of 50 years? What is the expected lifespan for newborns depending on their month of birth?

awjr 12y ago

Would be interesting to look at the 'stresses' that occur within schools. My 11 year old daughter was born on the 30th of August. Ergo she is the youngest in the year at school. She is studying with people that have a year of development on her. She is doing fantastically well but works hard to achieve that result. My hypothesis is that the age cut off in schools, unduly puts stress on the younger children in a class, that long term, impact on health in later years. In effect which month you are born in affects the stress you will feel during your school years as it will be inherently 'harder' for you.

beaumartinez 12y ago
I'd think the opposite. Since she is used to having to work hard from a young age, she will be more successful in life. Others who coasted through—whom were used to everything being relatively easier—will not have the experience she has already accrued when faced with a harder challenge.
- awjr 12y ago
  Not sure that makes sense. She potentially experiences 12 years of increased stress compared to her peers. I'm not implying that later in life, she will have better tools for work, but that her body would have spent most of her formative years under more stress. This would then reflect in a shorter lifespan. Note however that this concept she would gain the tools for hard working in itself is flawed. Studies have shown that those born in the Summer months have statistically lower exam scores.
  - theklub 12y ago
    If stress from school caused people to die earlier I think we'd know by now.
    - vidarh 12y ago
      How would we know? Why?
    - 12y ago

FranOntanaya 12y ago

I would think people conceived in warm weather are more likely to be from less stable relationships...