Chapter3b - Human Population Growth Human Population Very...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Human Population Growth Very dynamic in growth pattern Human population dynamics = “ Demography More detailed information are usually available Fertility and mortality rates, population age composition Increased ability to make population projections What will be the effect of reduced fertility rates on the ratio of retired people to workers in this society? Human Population
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Crude Birth Rate ” = number of live births per 1000 population in a given year World average is 21 (year 2006), ranging from ~10 (mostly developed countries ) to ~40 (mostly least developed countries) Meaning 6.59 10 9 (21/1000) = 138 million live births in a year It is called “ crude ” because it doesn’t take into account the fraction of population that is physically capable of giving birth in that year. Total Fertility Rate ” = the average number of children that would be born alive to a woman ( how many children per family). Ranging from ~1.6 (developed countries) to ~2.9 or more (least developed countries) Fertility Rate Annual Birth and Total Fertility Rates in U.S. Depression years
Background image of page 2
Replacement Level Fertility ” = the number of children that a woman must have !! To replace herself with one daughter in the next generation Account for the male and female births , as well as child mortality rate In U.S. , this number is “ 2.11 ” children, meaning 100 women will: - Bear 211 children, and statistically 108 boys and 103 girls - About 3 girls would be expected to die before bearing children - Leave a net of 100 women in the next generation again In many developing countries, where infant mortality rates are high , the needed replacement level can be ~2.7 children. The replacement level fertility doesn’t account for the influence from age distribution . For example, the phenomenon of “ population momentum ” beginning at 1980s in U.S. . Annual Birth and Total Fertility Rates in U.S.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 13

Chapter3b - Human Population Growth Human Population Very...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online