Factors responsible for mortality decline

- The role of medicine

- Major changes in life expectancy prior to 1920 occurred largely in the absence of germ theory

- Throughout the 1800s, miasma was the more accepted theory of disease causation; rotten smells in the air cause disease

        - One exception was smallpox vaccine (developed in 1760)

Macro-level and micro-level changes leading to the decrease in infectious disease

Changes in exposure, resistance, and recovery all contribute

Exposure

- Macro Changes: Sanitation, pollution, population density, pasteurization, labor conditions

- Micro Changes: Refrigeration, acceptance of public health initiatives, quarantine, hand washing, boiling milk

Resistance

- Macro Changes: Vaccination, food availability

- Micro Changes: Better diet

Recovery

- Macro Changes: Drugs, medical care

- Micro Changes: Access to and use of health care

            - Levels of mortality in US by occupation

- Preston looks at levels of mortality among US children by fathers’ occupation in 1895, 1905, and 1922/4

- In 1895, farmers and manufacturing managers’ kids have lowest mortality

- Farm and manufacturing laborers’ kids have highest

- In 1922/4, doctors and teachers’ kids have lowest

- Overall in 1922/4, higher educated classes have lower mortality than lower educated classes

           - Shows differential dissemination of information

            - More educated ppl can read and adopt public health info

- Segregation of population along class lines also probably contributed to differential death rates

Levels of mortality by age

- Vallin created graph of mortality in France by age 1720-1914

- Finds that decrease in mortality happened at pretty much all ages

- Main exception: death rates among young adults higher in 1877-1881 than in 1820-1829

            - Most likely due to migrating to cities

Notestein’s Theory of the First Demographic Transition

- Developed in 1945 in his article “Population—The long view”

- Describes the move from high fertility, high mortality regimes to low fertility, low mortality regimes

- Stage 1

            - Pre-industrial societies

            - Birth and death rates are high and approximately =

            - Population limited by food availability, fresh water, &  disease

- Stage 2

            - Early industrial societies

            - Characterized by technological innovations such as the   agricultural revolution and technological advances

            - Death rates plummet

             - Fertility does not plummet right away

             - High birth and low death rates -> population explodes

- Stage 3

             - Industrial societies

             - Birth rates fall

- Stage 4

            - Post-industrial societies

            - Low birth and death rates

            - Relatively stable population

            - Summary of how we as a species got to where we are today

- We can really only estimate the size of the global population with any degree of accuracy beginning in the mid 18^th century

- Prior to that, the next earliest time for which data are available was the early Christian era when Rome enumerated its population

- The population was approximately 8 million at the end of the hunter-gatherer era in 8000 BC

- The population grew somewhat with the establishment of agriculture to approximately 300 million by AD 1

            - By 1750 the population was about 800 million

- The history of the human population can be divided into two eras: long era of slow growth prior to 1750 and short era of fast growth after 1750

- In a stationary population, life expectancy equals the reciprocal of the birth rate

- This relation allows us to determine the most extreme fertility and mortality rates possible in a stationary population

- If each woman has 2.1 births (birth rate 13.3 per 1000) life expectancy will be about 75 years in a stationary pop

- If life expectancy is about 15 years, women who live to childbearing age must have an average of 8.6 children to maintain population size

- Differences in fertility can be attributed to 2 factors: differential exposure of women of childbearing age to risk of childbirth through marriage/cohabitation and differences in rates of conception and live birth among women who are married/cohabiting

- Henry defined natural fertility as the fertility of couples who do not modify their behavior according to the number of kids already born

            - Natural fertility still affected by custom, health, and nutrition

- For the period of long, slow growth in human history, it is probable that short-term variations in population size occurred frequently (likely not a uniform upward trend)

- Coale suspects that the small uptick in the size of the human population following the establishment of agriculture was due to fertility rates increasing more than death rates

            - Death rates likely increased due to more infectious diseases

- The demographic transition describes changes in fertility and mortality that accompany a nation’s progression from a largely rural, agrarian, and illiterate society to a primarily urban, industrial, and literate one

            - Mortality falling before fertility explains population boom

- In the premodern era the birth rate was relatively constant while the death rate fluctuated from year to year; in the postmodern era the death rate is relatively constant while the birth rate fluctuates

- Birth rates fell because couples wanted to have fewer children, not because new contraceptive technologies became available

- Less developed countries have been growing dramatically since WWII

- The present global population growth is due to moderate rates of increase in the developed world and very large rates of increase in the developing world

- Coale believes that at some point in the future the human population will inevitably return to a growth rate near zero

- What is undetermined is what combination of fertility and mortality will sustain this level of growth

 Book is concerned with the growth of population that began in the late 17^th century and has continued until the present day

-The modern rise in population is distinguished from previous increases by 3 things—its size, continuity, and duration

- Reliable data from vital records only available after 1838 in Britain and Wales

- McKeown’s method involves using data from this “post-registration period” to infer mortality patterns in the “pre-registration period”

-Believes that a declining death rate—rather than an increasing fertility rate—is the trend that needs to be explained in relation to population growth

- Decline in infectious diseases was primary contributor to decline in mortality

- Concludes that response to infectious diseases was modified by improved nutrition after ruling out the role of

1) change in the character of disease,

2) reduced exposure to micro-organisms, and

3) immunization (except smallpocs)

For TB:

1. Not genetics

2. Not environment, stress, physical or mental, still crowded and still have airborne diseases

3. Not a change in the frequency or amount of exposure to the disease

4. Not a change in the virus

therefore diet and higher SoL -> living

Public Health/santination about 25% of decline of mortaltiy

Decline in mortality not increase in fertility leads to increase in poulaiton

- This is essentially a negative conclusion, meaning that he arrived at it by process of elimination

- However, there are also positive reasons for believing that better nutrition -> reduced mortality, namely that a large increase in food supply coincided with a decrease in death rates

-McKeown uses current data from developing countries to infer what must have been occurring in 18^th and early 19^th century Britain 

- Data collected by the World Health Organization suggests that malnutrition makes people prone to catching and dying from infectious diseases

-Argues that “better nutrition was a necessary condition for a substantial and prolonged decline in mortality; without it immunization and therapy would have been of little value and reduction of exposure to some organisms less effective.”

- It seems to me like McKeown is confounding undernutrition and malnutrition

- Is it more food, a more balanced diet, or both that’s important for mortality declines?

- (138) Moreover, the reductions in mortality occurred primarily in childhood, at ages where nutrition is particularly important in lowering the severity of infectious diseases

- (142) Reduced exposure to disease due to improved quality of water and food more important in the reduction of mortality in the late 19^th century than in the late 18^th and early 19^th centuries

“Urban French mortality in the nineteenth century.” Population Studies. 32(2), 275-297.

- In the paper, rather than studying mortality at the national level the authors examine mortality in 3 regions in France—Seine (Paris), Rhone (Lyon), and Bouches-du-Rhone (Marseille)

- Comparing life expectancy in these 3 regions to life expectancy in France as a whole reveals that deaths in urban areas are greater than in rural areas

- Authors hypothesize that this is because disease spreads faster in urban areas due to greater frequency of interpersonal contact and sharing common resources

- However, region variation in urban death rates suggests that factors other than improvements in living standard (which occurred in all regions) are at play

- The most appealing candidate for comparing regional variation in death rates is the quality of the water supply and the techniques of sewage disposal

- Lyon improved water supply first and saw earliest drop in death rates, Paris was second, and Marseille third

- Mortality advantage did not occur immediately after cities improved their water supply because it took a while for households to implement new water facilities

- In addition, children saw the benefits more than adults, so mortality really improved on a cohort-by-cohort basis, rather than all at once

- Cause of death statistics confirm favored position of Lyon and disadvantaged position of Marseilles with respect to water-borne diseases (mostly diarrhoeal diseases like cholera and typhoid fever)

- However, air-borne diseases also related to quality of water supply because presumably people who are more sickly due to poor-quality water are more susceptible to these diseases as well

- In sum, the authors propose that improved water supply and sewage disposal, most likely in conjunction with improved nutrition, reduced the incidence of diarrhoeal disease among children and the incidence of other infectious disease

- These factors resulted in improved physical growth and development, which protected cohorts from later death from many causes, both infectious and non-infectious

- This argument accords with McKeown’s in that it finds little evidence that improvements in scientific medicine caused the reduction in death rates at the end of the 19^th century

- However, the authors place much greater emphasis on hygienic factors, which were largely the result of public health measures, and less on standards of living than does McKeown

roughly 50% of the reduction in mortality was due to “structural factors” unrelated to nutrition or economic development

decreases in infectious diseases, diarrheal diseases, and influenza/pneumonia/bronchitis were the biggest contributors to the mortality decline

the gains of mortality reduction are from fertility among increased survivorship

 “The importance of social intervention in Britain’s mortality decline c. 1850-1914: A re-interpretation of the role of public health.” Social History of Medicine, Pp. 1-38.

- Response to McKeown’s argument that medical advances and public health measures played little role in GB’s mortality decline

- McKeown’s thesis

- Argued that most of the important diseases involved in decreasing GB’s mortality levels had all but disappeared before the earliest date at which the relevant scientific medical innovations occurred

- Also argued that the major factor accounting for this mortality decline was a rising standard of living of which the most significant feature was an improved diet

- Critique of McKeown’s interpretation of the evidence

- Szreter argues that the main thrust of McKeown’s nutritional thesis is that it was simply the “last explanation standing”

- The main disease that McKeown focuses on is TB, and he dismisses public health measures as a possible cause to the decrease in TB because it is an air-borne disease

- However, Szreter points out that public health measures reduced overcrowding in urban areas, which very likely could have decreased the risk of contracting TB

- Szreter also doesn’t buy McKeown’s argument that airborne diseases such as TB and bronchitis were the first to decline; he argues that food and water-borne diseases declined first and contributed to the decline in airborne diseases

- Szreter’s alternative interpretation of McKeown’s data on mortality in GB

- Argues that death rates actually increased during the first 2/3 of the 19^th century due to overcrowding in urban areas

- Higher life expectancies in the country than in cities supports this claim

- Public health legislation in late 1830s-1875 paved the way for decline in diarrhoeal diseases, but it was not until the final third of the century, when these measures were actually carried out at a local level, that death rates began to decline steadily

- Infant mortality did not decline until the early 20^th century because it was not influenced by the water supply, but rather by the expansion of local housing standards, health and maternity services, and information of how to keep food fresh

- In sum, the “invisible hand” of economic growth did not cause the decrease in death rates at the end of the 19^th century, local government intervention did

- Szreter therefore warns governments not to expect increasing life expectancy to naturally follow from economic growth

- Human agency, in the form of an expanded public health infrastructure, is necessary to increase human longevity

- Demographic perspectives of mortality decline

Argue mortality decline in the 18th century  was shaped by drops in normal mortality not disappearance of mortality crises

- In England, mortality did not decline steadily until the 19^th century

- Wide regional differences existed in mortality rates within a given country

- The general causes of mortality decline remain unclear

- McKeown (1976) posits that improved nutrition was the main cause of decline

- Main problem with his argument is that he arrives at this conclusion merely by excluding all other possible explanations for decline

- In contrast, Preston argues that public health and sanitation were the main contributors to mortality decline

- The authors of the present article believe that these two explanations should be combined

- Exposure to disease likely more affected by sanitation whereas resistance to disease likely more affected by nutrition

- It is also important to distinguish between the incidence and lethality of disease

- Factors that affect the overall disease environment include urbanization, medicine, and preventative public-health measures

            - Major conclusions of paper

1. There was no simple or unilateral road to low mortality, but rather a combination of many different elements ranging from improved nutrition to improved education

2. Any thoroughgoing understanding of the mortality transition will necessarily be interdisciplinary

  “Economic growth, population theory, and physiology: The bearing of long-term processes on the making of economic policy.” American Economic Review, 84(3), 369-395.

Fogel argues that nutrition is the key mechanism via which income influences health

- Purpose of paper is to develop a theory to account for the secular decline in morbidity and mortality that takes account of changes induced in physiological functioning since 1700

- Decline in mortality in Britain and France took place in 2 waves

- First wave began during second half of 18^th century and lasted until beginning of 19^th century

- 2^nd wave began in the late 19^th century and continued until the present day

- Fogel argues that high prevalence of disease can cause malnutrition even if food supply is adequate by impeding the uptake of nutrients from food

- Caloric intake estimates from 1790 in Britain and France suggest that the population must have been pretty short and slim

- Even accounting for small stature, low calorie intakes also suggest that a substantial proportion of the population would not have been very productive in the labor market

- Fogel uses 2 indices—height and BMI—as proxies for malnutrition and health to predict risk of death at middle and late ages

- Height reflects health throughout life whereas BMI reflects more current nutritional intake

- Height and weight are likely predictive of mortality because they are associated with nutritional factors that affect the chemical composition of organ tissues, electrical transmission across membranes, the fxning of vital organ systems, etc.

- Finds that gains in BMI accounted for most of the reduction in mortality prior to 1870 and that gains in height accounted for most of the reduction after 1870

- Nutritional state not only affects risk of death due to infectious diseases but also affects risk due to chronic diseases

- This study suggests that childhood malnutrition may affect health throughout life (both vulnerability to infectious diseases and risk of chronic diseases)

- Increased caloric intake affects labor productivity both directly (more energy) and indirectly (disease)

            - Implications for economic growth

 Purpose of article is to provide a historical overview of demographic transition theory

- Demographic transition theory states that societies that experience modernization progress from a pre-modern regime of high fertility and high mortality to a post-modern regime of low fertility and low mortality

- The theory is descriptive rather than explanatory

- Most demographers find fertility decline harder to explain than mortality decline

- Notestein attributed fertility decline to primarily socio-economic causes

- Industrialization stripped the family of many of its fxns in production, consumption, recreation, and education; education and a rational point-of-view became more important and as a result the cost of child-rearing grew; falling death rates lowered the inducements to have a lot of births; etc.

- Criticisms of demographic transition theory

- Its accuracy based on data from European demographic history (for instance, ignored variation in pre-modern fertility)

- Fertility decline doesn’t always occur after mortality decline

- Fertility decline not accurately predicted by socio-economic factors (some countries appear to experience decline before reaching modernization)

Coale posits three conditions necessary for fertility to fall:

1. Fertility must be within the realm of conscious choice.

2. Reduced fertility must be perceived as advantageous.

3. Effective contraceptive techniques must be available.

European Fertility Project designed to study historical fertility decline in Europe

- One of its key contributions was the discovery that the fertility transition has occurred under diverse socio-economic circumstances

- Empirical data suggests that both the mortality and fertility transitions have picked up tempo over time

- Fertility transition now beginning at increasingly lower levels of socioeconomic development

- Mortality reduction and fertility reduction believed to be linked by economic development

- Various factors have been hypothesized to be the leading factor in fertility decline

- Economic theories of fertility decline propose that reduced demand for children due to income, prices, and tastes were to blame

- However, Caldwell points out that modernization isn’t a necessary precursor of fertility decline

- He hypothesizes that Westernization is a more important force of change, which includes ideas of progress, secularization, mass education, and mastery over environment

- Cultural and ideational theories hypothesize that fertility decline is related to the degree of secularism, materialism, and individuation in a culture

Government policy may also play a key role in fertility decline

- Nativity policy (ex. China)

- Policies related to female education and women’s rights

“Reform and support systems for the elderly in developing countries: Capturing the second demographic dividend.” Genus, 62(2), 11-35.

The authors show that the demographic transition and population aging present two opportunities for economic growth

The first demographic dividend arises because the working age population is growing more rapidly than the consuming population due to decreases in fertility and mortality at younger/middle ages

- Provides an extra boost to income per capita

- However, this demographic dividend is transitory because the number of consumers will grow faster than the number of workers as a large part of the population becomes concentrated at older ages

The second demographic dividend arises because fewer children and a longer life create a powerful incentive for individuals to accumulate capital to provide for old age

- Investing this capital in the domestic or global economy will result in rapid growth of output per worker

- Parents investing in the human capital of their children (through education) would also produce a second demographic dividend

- Furthermore, this process could have a permanent positive effect on the economy

If, however, individuals rely on familial or public transfers to provide for old age, this will not increase output per worker

- It is therefore the responsibility of law-makers and public policy to encourage people to save and invest their money by creating and supporting the necessary financial institutions

- Authors conclude that the pessimistic predictions regarding the effects of population aging on economic growth are not necessarily warranted, so long as aging countries exploit the economic potential of the second demographic dividend