Week 1, Lecture 2: Demography

What is Ageing?

• Very complicated
• Austad - Why we Age
• Bond And Coleman - Ageing in society ch1
• the study of aging really matters to everything in society, the economy etc.

Essential ingredients in aging

• survival,
• change: biological, psychological, social
• Probability of death

Pub Glass Death

• There is a linear relationship between time and 'death' of pub glasses as there is equal chance them dying at any point
• In wild populations, early and late age stages are more likely to have high risk of death compared to those who are middle age
• Pressure of mortality
• Protected populations: we do most of our dying at the end of our lives. rectangularised pattern.

Important Terms

• Life expectancy: how much life can be expected of an individual from a certain age. Usually referred to from borth
• Life Span: the life potential, defined from birth

Survival and aging

• Biological ageing is characterised by an increasing liklihood of death with increasing age.
• The Gompertz Function: in any given population mortality rates increase with age in a 'geometric' progression. He was really smart and worked in the insurance industry. He said that mortality rates double every 'x' years. He looked at life tables which list when people die. He made a exponential function
• Mortality Doubling Rate: there is a period after a certain age when the likelihood of dying doubles. This happens approximately every 7-8 years, and starts at about 11 years of age.
• This is a very biological way of looking at aging but not a way that people will assiciate their own aging processes

How and why patterns of survival are changing.

• Can look at dying curves over time
• In ancient times, there was a much more linear curve. In later years however there is a large bulge that occurs.
• Life Expectance has increased generally except for in times of great disease

L/E L/S

Greece 110BC 35 100

Rome 753 BC 32 100

England 1276 48 100

England 1385 38 100

USA 1950 70 100

• 65 is a key age
• the proportion of people over age 65 has increased significantly
• the proportion of increase in the oldest people within the older population are increasing the most.

Population Aging

• A demographic transition
• The median age of the population is increasing
• Transition from a young society to an aging society. It is occuring in all developed countries in the world
• This increases the interest in the study of aging both scientifically and politically.

Why are societies aging?

• Better healthcare: less disease...wrongg
• We naturally think aging is something that happens to old people.
• Three things influence why the change is taking place

1. mortality is changing
2. fertility is changing: average age will increase if this decreases
3. migration: if there is an out migration of young people, the mean age will increase

• plumbing- substantially increased survival rates
• Healthcare and public health, for both older people and babies. When babies stopped dying, people started having fewer babies,
• Women always live longer
• It is not what happens to elderly people that influences aging of population. It is the production of babies.
• life expectation for babies has increased massively
• 'Replacement Level' - approx 2.1 babies/woman is the amount of babies required to maintain the population
• Current fertility level - 1.74
• Baby boom/postwar period - 1961 ish
• Low fertility levels have implications for the economy

Demographic Transition

• main problem is reduced fertility
• followed by substantially reduced mortality
• and laterally improved healthcare
• this will result in an even more rectangular curve.

what about everybody dying from heart disease, diabetes etc....