Age at Death vs. Average Age at Death

statisticsI am seriously into crunching numbers lately!! Comments about this and my previous two blog postings are welcomed.

I talked with my brother over the holiday who stated that our ancestors all died young.  I wondered why I hadn’t looked at this question, since I had the data to either confirm, or deny his hypothesis. So, I crunched the numbers.

Process

Several questions were raised concerning the development of the analysis:

  1. Where can I find data as to the average lifespan of a person born in XXXX year?
  2. How many generations should I go back?
  3. If that person did not emigrate, would that make a difference?
  4. Should I use predicted life span based on birth year or should I use a life span predicted if one lived to age 20, effectively eliminating childhood deaths?
  5. Should I separate men and women?

Here’s what I did:

  1. I found that data for the US at  http://www.infoplease.com/ipa/A0005140.html.[1] The data is incomplete particularly in the 1800s.
  2. I went back four generations, starting with my parents, because I have documented data back that far on both maternal and paternal sides.
  3. I identified the ancestors who immigrated and those who did not.
  4. I decided to use data which predicted age of death based on a person who lived to 20 years of age. If I used birth year only, the average life span of the individual  would be shorter. The method of using the predicted age of death at 20 years of age is therefore, more conservative when calculating the numbers of years more or less the individual lived compared to the average.
  5. I split the data by gender as it quickly became apparent that there were some trends that were gender based.

Hypotheses

Contrary to my brother’s statements, I hypothesized that:

  1. My male ancestors would live at least as long as average for their time in every generation.
  2. My female ancestors would live at least as long as average, but less than men, in every generation.
  3. My immigrant ancestors would die on average at an older age than those that did not immigrate in every generation.

If my hypotheses 1 and 2 are correct, my brother’s supposition is incorrect. I just threw in the 3rd one because I wondered what I would see.

My maternal and paternal ancestor’s familial and cultural norms dictate marrying approximately between the ages of 25-32.  My span of years covered in 4 generations (starting with our mother and father) is from 1931 (birth  + 20) back to 1808 (birth+20) –about 120 years for four generations. (My brother and I, and our children are continuing the tradition of late marriages and late childbirth.)

Summary of findings

My hypotheses were correct for numbers 1 and 2; my hypothesis for 3 was incorrect.

 

  1. Our male ancestors lived longer than average in every generation.
  2. Our female ancestors lived longer than average, but less than men, in every generation, except the 4th. The 2nd, 3rd and 4th generations were statistically average.
  3. Our non-immigrant ancestors died at an older age than those who immigrated.

Looking at the data

 

 

  • My male ancestors live longer than average for their time in all four generations.
    • All men in the 4 generations died at an average age of 70.1 years. All men who survived to 20 years of age have a predicted average lifespan of 60.5 (incomplete data from site in 1800s). That means my male ancestors died on average 10.6 years later than predicted for a 20 year old of the era.
    • By generation the results for all men were:
      • 1st generation (my dad): died at 82 years of age. The average life span of a surviving male 20 year old born in 1911 is 62.5 years of age. My father lived 19 years past what would have been predicted for him as a young man.
      • 2nd generation (my 2 grandfathers): averaged 71 years of age at time of death. The average life span of a surviving 20 year old born in mid to late 1800s in the US was 6o.6 years of age. My grandfathers lived an average of 11 years longer than what would have been predicted for them as young men.
      • 3rd generation (my 4 great grandfathers): averaged 70.8 years of age at time of death. The average life span of a surviving 20 year olds born in the mid-1800s in the US is 6o.6 years of age. My grandfathers lived an average of 10 years longer than what would have been predicted for them as young men.
      • 4th generation (my 8 great great grand fathers): averaged 69.8 years of age at time of death. The average life span of a surviving 20 year old born in early 1800s  is 6o.1 years of age. My grandfathers lived and average of 9.7 years longer than what would have been predicted for them as young men.
      • There are three significant male “outliers” in generation 4. Two men live extraordinarily long lives: a Swede who died at age 91 and an Ostfriesen who died at age 84. One individual, another Ostfriesen, died early at age 47 of unknown causes.
  • My female ancestors  are much more mixed, but perhaps predictably so. Generations 2, 3 and 4 showed little change in survivability from one generation to the next. A huge increase is seen in generation 1, probably due to improved health care, survivability in childbirth, and the small sample size .  The average age at death for generations 2, 3 and 4 are statistically the same and very close to the predicted age of death.
    • By generation, the average for all females was:
      • 1st generation (my mom): died at 84 years of age. The average life span of a  20 year old female born in 1911 is 62.5 years of age. My mother lived 21.5 years longer than what would have been predicted for her as a young woman.
      • 2nd generation (my 2 grandmothers): averaged 65 years of age at time of death. The average life span of a female 20 years old and born in the US in the 1880s is 62.3 years of age. My grandmothers lived an average of 2.7 years past what would have been predicted for them as young women.
      • 3rd generation (my 4 great grandmothers): averaged 63.8 years of age at time of death. The average life span of a  20 year old born in the US in the mid 1800s was 6o.2 years of age. My grandmothers lived an average of 3.6 years beyond what would have been predicted for them as young women. Their  is one significant outlier in the 3rd generation: a female who died at age 23 in childbirth. All three others lived past the average age at time of death–13 to 24 years.
      • 4th generation (my 8 great great grandmothers): averaged 59.3 years of age at time of death. The average life span of a surviving 20 year old born in early 1800s  is 6o.2 years of age. My grandmothers died an average of 1 year earlier than what would have been predicted for them as young women.
        • In this group, 6 of the 8 died prior to their predicted time but the number of years less than the predicted times was small.  The two women who lived longer than their predicted time in this generation, lived an average of 16 years longer. These extremes of small and very large deltas create some difficulties in drawing conclusions.
  • It was hypothesized that my immigrant ancestors would live longer than the predicted life space of a 20 year old in the US than those that did not immigrate.  Only one generation and one gender seemed to benefit with increased life span from immigrating, females born in the early 1800s. Small sample size  and four generations where there were not immigrants to provide data dictates a lack of scientific predictability across families.
    • Of the 15 male candidates, nine were either born in the US or immigrated to the US.
      • 1st generation: no comparative non-immigrating ancestor
      • 2nd generation: no comparative non-immigrating ancestor
      • The 3rd generation is contrary to the hypothesis: the non-immigrating ancestor lived longer than the ancestors who immigrated.
      • The 4th generation is contrary to the hypothesis: The non-immigrating ancestor lived longer than the ancestors who immigrated.
    • Of the 15 female candidates,  nine were either born in the US or immigrated to the US.
      • 1st generation: no comparative non-immigrating ancestor
      • 2nd generation: no comparative non-immigrating ancestor
      • The 3rd generation is contrary to the hypothesis: The non-immigrating ancestor lived longer than the ancestors who immigrated.
      • The 4th generation supports the hypothesis. The immigrating ancestors lived longer than the ancestors who did not immigrate.

Conclusion

My brother’s hypothesis is incorrect. My hypotheses concerning age at death compared to average of the era is correct. My hypothesis that the immigrant’s average age at death would be older than those who did not immigrate was incorrect. Both the male and the recent female lines live longer than average. The average of life spans of females born in the early 1800s (4th generation) is statistically average. Immigration does not lengthen the age at time of death, but rather the non-immigrant, on average, lived longer than the predicted age of death by more than the immigrating ancestor.

There are two reasons why my brother would have the perception that our ancestors died young. Because our ancestors married late and also had children late, my brother and I were young when our known ancestors died, e.g. I was 7 when my last grandparent died. Others, whose parents married and had children in their 20’s or even earlier, would be older when their parents and grandparents died.

Happy Hunting!

Jill

What I have done since the last post: I recuperated from the wedding with my hubby in CO. I quit skiing about 3 years ago and instead worked on my next year’s presentations. I also started looking very seriously at the DNA kits I manage and purchased upgrades (great sale at FTDNA!). I have to wait for some test results to comeback (mid to late January) but I did upload what I had to GEDmatch, a third party tool for comparing data across companies. For Christmas I got a trip to DC for GenFed if I am quick enough on the 25th to get in.

[1] I am not particularly happy with this site and its data, so if you know a better website with more consistent coverage, let me know. I will redo the results, although I do not predict a difference in the outcomes.

 

 

 

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4 comments on “Age at Death vs. Average Age at Death

  1. Ginny says:

    For pre-1900 life expectancies, see https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885717/ , tables 4 and 5.
    For 1900+ check out http://census.gov

  2. cottew1 says:

    Very interesting, Jill. I think I may use your idea and check on my ancestors.

    Betsey

  3. Kay Crabtree says:

    Fascinating. I need to look at mine too.

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