POPULATION PYRAMIDS & HISTOGRAMS Age structure POPULATION PYRAMIDS & HISTOGRAMS

AGE STRUCTURE A-Expanding/growing population- pyramid shape, has more children than any other age group.- Nigeria B- Stable populations- Number of children is roughly the same as the number of reproductive adults- US C- Declining population- Pre-reproductive group is smaller- Germany

Take a closer look... Age structure graphs group the population into age groups of 5 year increments The “bars” are the percent of each age group that is male (left) or female (right)

What are age structure diagrams? Even if the replacement-level fertility rate of 2.1 were magically achieved globally tomorrow, the world population would keep growing for at least another 50 years.   The reason for this is a population's age structure: the proportion of the population (or of each sex) at each age level. Population Geographers typically construct a population age structure diagram (also called histograms) by plotting the percentages of numbers of males and females in the total population in each of three age categories: prereproductive (ages 0-14) reproductive (ages 15-44) postreproductive (ages 45 and up)

How does age structure affect population growth? Any country with many people below 15 years old (represented by a wide based population structure diagram) has a powerful built-in momentum to increase its population size unless death rates rise sharply.   The number of births rises even if women have only one or two children because of the large number of girls who will be soon moving into their reproductive years. In 2012, 30% of the world's people were under 15 years old. These 2.2 billion people are poised to move into their reproductive years

How can this growth be slowed? an effective program to reduce birth rates a sharp rise in death rates  

Describe the growth of this country Population is EXPANDING High percent of population is in pre- reproductive/reproductive years...so there will be a high birth rate over next several years Low percent of population is in older years This is a developing country Will experience resource depletion & decreased quality of life

Describe the growth of this country Population growth is SLOW % of each age group is relatively even TFR is below replacement level Column with bulges/pentagon shape This is a developed country Will need to be able to support a rapidly aging population

This is current US population pyramid What might the US government need to be concerned about in the future? Rapidly increasing aging population...retired...will need support Baby Boomers are in their 50s and 60s

The Baby Boomers!

Calculate % population under 15 For KENYA For the US For Italy ~45% ~ 20% ~15%

Which of the following is the best description of a population with a stable age distribution? A. Large population growing at a constant rate B. Growing population in which the proportions of individuals in different age classes remain constant C. A small population that has not yet achieved exponential growth D. A large population with a negative growth rate E. A population in the early stages of logistic growth

Which of the following is the best description of a population with a stable age distribution? A. Large population growing at a constant rate B. Growing population in which the proportions of individuals in different age classes remain constant C. A small population that has not yet achieved exponential growth D. A large population with a negative growth rate E. A population in the early stages of logistic growth