Demography is a broad social science discipline concerned with the study of human populations. Demographers deal with the collection, presentation and analysis of data relating to the basic life-cycle events and experiences of people: birth, marriage, divorce, household and family formation, employment, aging, migration death.

People migrate in two ways. People move into a country where they are not a native from another place. Immigration People move out of a country in which they are a native, to another place. Emigration Ellis Island: Processing in 1840’s Irish Potato Famine

The U.S. population is undergoing at least two major shifts: a significant change in its geographic distribution and a similarly important change in ethnic composition. Immigration--accounting for a third of the present annual growth- -is also an undeniable factor. Demographers use a numerical equation to express the rate at which all populations grow. Considering the world as a whole, the fundamental demographic equation is: Population Growth Rate = Birth Rate  Death Rate Most demographers modify this equation a bit. In order to take immigration, and emigration into consideration, the following equation is used: Population Growth Rate = Rate of Increase  Rate of Decrease Immigration and emigration both impact populations.

…in developing industrialized countries… EARLY. Each successive age group is smaller than the preceding age group. The working age population (shown in orange) has to provide for a comparatively large population of children. However, children can help their parents in growing food, collecting firewood, etc. Middle:. The age pyramid is dominated by the working age groups. The working age population is potentially well able to support the old and the young. Notice the left-right asymmetry. This is because women tend to live longer than men. LATE. Now the pyramid is almost rectangular in shape. The working age population needs to support a large population of older people

200 million couples have intercourse 100 million billion sperm are released 50 million ovules are produced 800,000 are fertilized 400,000 babies are born (no pictures available)

How many babies could a woman biologically have in her lifetime? Fertility begins at Fertility ends at menopause (50-60) Although, the youngest mother whose history is authenticated is Lina Medina, who delivered a 6½-pound boy by cesarean section in Lima, Peru in 1939, at an age of 5 years and 7 months. How many babies could each woman have? Hypothetically, a woman could have 32 babies over her lifetime, given the extreme statistics above, and that’s not accounting for multiples! Technically, a woman could give birth every 18 months of her child-bearing years. The TFR (or total fertility rate) of a population is the average number of children born to a woman in her lifetime in that culture.

Looking at the lower end of the statistics, most women could potentially have 15 single-birth babies, but practically never achieve this number. Why? The main reasons are: Why isn’t the Earth overcome with babies?  The use of birth control  The practice of breastfeeding, nature's way to delay the next birth  The institution of marriage, which delays the first birth The highest officially recorded number of children born to one mother is 69, to the first wife of Feodor Vassilyev ( ) of Russia. Between 1725 and 1765, she gave birth to 16 pairs of twins, seven sets of triplets, and four sets of quadruplets. 67 of them survived infancy.

Death…an everyday experience 151,000 people die 30,000 of them are children dying from starvation under 5 50,000 people die from infection 35,000 from cardiovascular disease 15,000 die from cancer 10,000 die from violent means 10,000 children die from diarrhea 1,000 women die in childbirth

Will we all live in large cities? In 1994 one of every two people lived in the vicinity of a city, while only one in ten did so in The country folks are becoming city dwellers. Managing such large cities could well become the most difficult problem of the next century City dwellers, soon to be the vast majority, will live in megalopolies of millions to tens of millions inhabitants. A megalopolis is a metropolitan area with an excess of 10 million people.

Which continent has the largest number of cities numbering 5,000,000 and over since 1950? What US City has had the largest population the longest?

Just how do we know how many people there are, anyway? Americans have one of the longest records of continuous population censuses, beginning with the first count in required, then as now, by the U.S. Constitution for the purpose of allocating seats in the House of Representatives. The U.S. Census Bureau--an arm of the Department of Commerce--has always conducted the census in years ending in 0.

A look at world demographics!