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Unformatted text preview: Week 11: Lecture Outline Hierarchies and Health (recap & conclusions) Biodemography `Deadly Harvest' (Sawchuk & Rogers, 2005) `Conspiracy in Fairport' (Sawchuk & Rogers, 2007) Humans, Hierarchies and Health A KEY POINT regarding the SES gradient is that poor health is not so much the outcome of being poor, BUT
feeling poor, that is, feeling poorer than others Suicide Rates in Gibraltar, 1878 - 1945 Biodemography of Aging Central Aim ? to discover a biological pattern to the dying out of individuals within a population Concerned with providing a biological rationale for the timing and causes of death in humans and other sexually reproducing species Why do organisms senesce? "age related changes in an organism that adversely affect its vitality and functions (Finch, 1990:5)" Life Expectancy: Through the Ages Source: `The Sociology of Aging.' (Harris & Cole, 1981) Why Not Immortality? "The Price we pay for Sex is Death" reproduction generates the new bodies needed to survive in a hostile environment & death is the way nature discards the old, worn-out bodies Human bodies as genetic transport vehicles humans are directed to grow, develop, and reproduce so that the genes hitching a ride can move onto the next generation Genes are immortal not the bodies that carry them Aging, disease, and death are natural by-products of bodies that were optimized for reproduction The Law of Mortality Mortality Pattern Across the Life Span: 1960 Costa Rican Males The Law of Mortality Age specific death rate, per 100,000 people. United States. Biodemography of Aging A law of mortality should predict when organisms die from a degradation of the vital forces that are intrinsic to the integrity of their own bodies In the real world, however: people and animals die from all sorts of things that have nothing to do with intrinsic causes of death: accidents, suicide homicide, infectious and parasitic disease, predators New methodological techniques make it possible to distinguish between extrinsic and intrinsic causes of death mathematically eliminate extrinsic causes of death should reveal an underlying law of mortality `Stochastic Problem' "To understand the biological forces controlling our lives, it is first necessary to determine the underlying average processes which appear to operate, and then to analyze the way in which stochastic factors modify those processes" Stochastic Synonymous with `random', `pertaining to chance' Research Application if stochastic causes of death (i.e., extrinsic) can be identified, then it is possible to filter them out mathematically in order to arrive at an approximation of the underlying `true' mortality signature in humans. Extrinsic mortality "A death that is either caused or initiated by processes that originates outside the body of an individual" e.g. infectious and parasitic disease, predation, starvation, natural disasters, homicide deaths occur at an earlier age than would have been predicted from the physiological state of the organism had the external force not existed. Intrinsic mortality "Deaths that arise primarily from the failure processes that originate within an organism" incorporates both senescent and inherited diseases Conceptually, intrinsic causes of death are those that remain after the total elimination of extrinsic causes of death
Source: Carnes et al. (2006) Biogerontology 7: 183-198 Extrinsic Mortality in Humans Source: Carnes et al. (2006) Biogerontology 7: 183-198 Intrinsic Mortality: Thought Experiment Animals are maintained in an optimal environment, completely protected from infectious disease, aggression, fatal accidents, etc... In this scenario, all deaths arising from external forces are eliminated Every animal in this hypothetical population would achieve their life span potential and succumb to an intrinsic cause of death Biodemography: Methods Combines the demographic perspective of the life table with epidemiology, and evolutionary biology Life table an actuarial table based on age-specific mortality statistics that follows an entire cohort from birth to death an important methodological device for studying mortality, but can be applied to any "duration" is the standard method for assessing mortality in human populations The Life Table Life Tables are mathematical devices used to measure some phenomenon Invaluable indicators of the health of large population aggregates such as nation states Widespread applications in Anthropology skeletally derived populations, historical data from parish registers and census data Life Expectancy at Birth International recognized measure of community wellbeing Provides a convenient summary measure of mortality both layman and expert can easily appreciate this measure Technically, it is unaffected by the age distribution of the population & allows the researcher to examine intrapopulation level comparisons (e.g., gender and class) interpopulation level comparisons (e.g., geographically distinct populations) Life Expectancy at Birth Main Findings Males had shorter life expectancy that females across all age groups This sex difference in mortality had not been demonstrated in previous Japanese paleodemographic reconstructions What accelerated the death of males in the medieval period ??
males were directly or indirectly involved in war Historical Biodemography Gibraltar: Life Expectancy at Birth
Year 1911 1931 1951 1970 1981 1991 Males 46.1 49.7 63.3 68.5 71.4 73.4 Females 53.6 58.2 70.8 73.6 75.5 80.4
SOURCE: Purcell (1996) Olshansky, Carnes, & Grahn (1998). American Scientist. 86: 52-61 Biodemography: Background Context Human Life at its Beginning The environments that shaped humans were hostile and dangerous High mortality rates from extrinsic causes of death at young ages has characterized human evolution Implication of a hostile environment if an organism delays reproduction it runs a very high risk of not reproducing at all the longer reproduction delayed, the more likely it is the organism will die from an extrinsic cause of death e.g. predation, accidents, infectious or parasitic disease Neolithic Revolution Social Stratification Sudden and dramatic increase in mortality occurring from a single triggering source over a very short period CRISIS MORTALITY
Famine Floods War Epidemic Disease Biodemography: Background Context Response to hostile environment and high extrinsic mortality risks
Attain sexual maturity as early in the lifespan as is physiologically possible Early reproduction (relative to potential lifespan) to counter high extrinsic mortality Changing Tides of Death Within a Few Generations the highest risk of death has shifted from the young to the old infectious and parasitic have been replaced by chronic degenerative diseases as the primary causes of death Control over infectious and parasitic diseases via numerous Public Health Measures Clean water, sterilized foods, sanitation, waste treatment & disposal, refrigeration, controlled living environments, dental & medical hygiene, improved diets, and antibiotics Improved public health measures and medical technology have circumvented the forces of natural selection that shaped the human gene pool in the past permitted individuals to survive and reproduce who would have been denied this opportunity in the past Life history strategy of a species can be likened to a race car Objective: `Win the Race'
SOURCE: Olshansky, Carnes & Grahn (1998). American Scientist. Vol. 86: 52 ...
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This note was uploaded on 04/18/2008 for the course ANT 203 taught by Professor Purcell during the Spring '08 term at University of Toronto- Toronto.
- Spring '08