Genetics and Longevity

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Genetics and Longevity

• Human Studies

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Genealogical Studies
Bell - 1918 Descendents of William Hyde (died
1681) n 8,798 correlation between parental
longevity and offspring longevity greater
influence of father ?
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Yuan - 1932 Chinese family 1365-1849 (n 7,500)
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Jalavisto (1951) 12,876 Scandinavians
(1500-1829) maternal longevity better
predictor Mayer (1991) - New England
1578-1963 n 14,549, 6 families what portion
of longevity is genetically inherited ? Does
this value change over time ? 95 confidence
limits 0.10 -0.33 (10-33) heritability does
not change with time
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Population Studies
Actuarial Studies - parental age has affect on
length of life of offspring father longevity
better predictor details of ind. Studies vary
slightly, but overall trend is clear
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Twin studies
Not all familial effects are genetic twin
studies can sort this out Kallman 1957 - 1739
pairs of twins at least one twin 60 effects
of parental life span as well as similarity
between twins fraternal vs. identical Correlat
ion between parental span and offspring
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Twins
Avg. difference between fraternal twins 6
years for same sex twins, 9 years for diff.
Sex Identical Twins - 3 year diff. Heritability
- 0.33 to 0.5 Heredity is an important factor
determining life span What we inherit is the
absence of a tendency for a short
life Biomarkers a better measure of age related
changes ? Genetic vs. Environmental Control
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Gender Differences
Stronger Sex ??
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Gender Gap
Differential Mortality Changes Sex Ratio At
conception 170100 (est.) End 1st Trimester
130100 At Birth 106100 Adolescence
100100 Age 75 60100 Why ? Genetics ? Biology
? Behavior ? Environment ?
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Gender Gap
Y-Chromosome- 78 genes, all but 18 directly
involved with spermatogenesis (sperm production)
Single Y Chromosome- no chance for genetic
recombination Proband males (partial
deletion of Y chromosome) 82.4 years vs. 77.4
for females (in same family)
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Gender Gap
Role of androgens ? (testosterone) eunuchs
(postpubertal castration) live longer than
controls Physiology vs. Behavior
?? Testosterone given to female mice lowers
their immune response Protective effects of
estrogen in coronary artery disease Waldron 1987
- 18 of gap due to hormone diff. 55 due
destructive behaviors Smoking, guns, cars,
alcohol
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Gender Gap
In U.S. Gender Gap has doubled since
1900 (argues against biological/genetic
explanation) Other ethnic/ cultural / societal
groups Gap varies (10 years to -2.8) Males live
longer in 6/157 populations general high rate
of premature death mortality of
childbirth female infanticide Other animal
species - males live longer in some