January 21, 2011 - January 21 January-21-11 11:48 PM...

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Conclusion of mortality rates & birth / fertility rates Comments on assignments 1. Problem #7: temporal variation in growth rate; relevant formula is on handout with collected formula - Math involved is simple probability and algebra that most people should know how to use for everyday life - Formulas should be understood in terms of words, not symbols; should make an example to be sure you understand them - Finishing mortality lecture 2. Summary from last week (basic facts of mortality rate) A. Mortality shows a U-shaped relationship to age - So, 8 yr. doubling time by age of 30 Moartality due to senescence starts to be seen at age 12-13 and is characterized by a constant multiplicative increase per year past the age of 30, resulting in 8 year doubling time - Mortality rates differ for many reasons other than age and are currently decreasing in most countries - Various factors are related to mortality rate B. Therefore senescence is not the only factor. - Reproductive effort or growth effort changing with age Definition: aging or senescence is the decline in physiological functioning that results in mortality rates increasing and / or fertility decreasing with age after some point in the lifespan within most biological species Senescence Immune system not exposed @ birth. During course of childhood, immunity is acquired from external exposure, hence, declining mortality rate. Both of these things change with aging. Education Female 1/3 mortality rate for those with college than those with less than high school diploma As education level increase, mortality rate decreases Better job means greater economic benefit College education = wiser decision-making Correlation between intelligence and better gene? Why? There is no firm biological explanation at the moment. (graph: death rates per 100,000 as a function of educational achievement, sex, and age in US) Learning / immunity (education) Outgrowing predators or sources of accidental mortality Other factors: - We will concentrate on senescence - Lack of repair / regeneration as an aspect of senescence C. (mortality increases with aging for organisms) Injuries accumulate with age Unrepairable damage causes higher subsequent mortality Inability to regenerate lost limbs Inability to regenerate body parts Why? - January 21 January-21-11 11:48 PM January 21, 2011 Page 1
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Why not 4 kidneys? 2 hearts? Consider cost to having extra copy of organs (not worth the cost) Organs with only one or two copies Even with perfect cell-level repair, humans would exhibit increasing mortality with age
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This note was uploaded on 06/20/2011 for the course EHJ EHJ351 taught by Professor Peterabrams during the Spring '11 term at University of Toronto- Toronto.

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January 21, 2011 - January 21 January-21-11 11:48 PM...

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