“Why should you consider taking a demography course in college?” That’s the question Joel Cohen, noted demographer and professor at Rockefeller and Columbia University, looks to answer in a 45-minute introduction to demography produced by the Floating University and released for free on YouTube.

“You will be growing up in the generation where the baby boomers are going into retirement and dying, you will face problems in the aging of the population that have never been faced before, you will hear more and more about migration…between rural areas and cities,” says Cohen. “You need to understand as a citizen, and as a taxpayer, and as a voter, what’s really behind the arguments.”

Cohen’s lecture is lesson one in the Floating University’s online Great Big Ideas course, which debuted in fall 2011 at Harvard University, Yale University, and Bard College and was accompanied by weekly in-class discussions. Courses are geared towards undergraduates but are open to anyone and cover a range of subjects such as history, linguistics, globalization, economics, and political philosophy. Using some of the best and brightest from academia, along with high-quality and engaging production values, Floating University has developed a unique product.

A Bathtub With No Stopper

The world’s population has grown rapidly since 1600, when there were only half a billion people, Cohen explains. It now sits at seven billion, and even though the rate has slowed since the 1950s, global population continues to grow at a rate of 1.1 percent per year.

Cohen likens the situation to a bathtub with no stopper: the constant flow of water reflects fertility rate, the drainage represents the mortality rate, and the amount of water in the tub is total population. If the replacement fertility rate – the number of children that must be born to cover the death rate and stabilize the population – far exceeds the mortality rate, then the world’s population will swell (and perhaps even “overflow” the lid of the tub if carrying capacity is overcome).

However, small changes in fertility rate (drip rate) can make a large difference, Cohen points out. If current fertility rates were to remain constant, the world would surpass 10 billion people  by 2050. However, a drop in global fertility from 2.5 to 2.1 (the magical replacement fertility number) would decrease world population projections to 9.3 billion in 2050. The UN projects that this is likely to happen, based on patterns of fertility decline observed in developed countries. But stalls and reversals have occurred, and sub-Saharan Africa, the Middle East, and South Asia will be the key regions to watch in this regard.

According to Cohen, a combination of young populations and high fertility rates means that, at a minimum, an extra three billion people will be born in the developing world – mostly in cities – over the next 40 years. Unfortunately this means growth is happening in the places least able to afford it. An astounding one billion people are already hungry, one billion live in slums with limited or no access to adequate water and sanitation, and another (sometimes overlapping) billion are illiterate. Two-thirds of those billion illiterate are women, and nearly 215 million women worldwide have an unmet need for contraceptives.

A Comprehensive Challenge

Cohen has been studying the population-natural resource equation for decades. He explains the evolution of his thinking, research, and experiences during the course of the lecture.

In 1996 he authored How Many People Can the Earth Support?, but soon moved from trying to determine a “quantity that depends on future events, processes we don’t understand, and values that may change over time,” to focusing on solutions instead. Initially, Cohen concluded that better and more comprehensive education at primary, secondary, and especially tertiary levels was the best way to deal with the challenges of both rapid population growth in developing countries and aging in developed countries (a separate but related challenge). He soon realized, however, that education is useless without a healthy brain. Hunger and malnutrition often cause irreversible damage to the development of young minds and bodies.

Now, he advocates for a more comprehensive approach that includes encouraging education but also preventing unintended pregnancies; opening markets to small farmers and extending credit to women; eliminating subsidies in rich countries that hurt poor people; using farmland for farms (not cities); promoting health and nutrition for all; limiting the use of chemicals to those that are the least harmful to the environment; and funding more agricultural research to use crops as food, not fuel.

Using Demography as a Tool

“Demography gives you the tools to address and to understand these problems,” said Cohen. It’s the “central subject related to economics; to human well-being, in material terms; to the environment; to the well-being of the other species with which we share the planet; and culture, which affects our values and how we interact with everyone.”

It provides solutions too, it is just a matter of acting upon those solutions and doing so quickly before it’s too late, he said.

Cohen’s broad take on demography sets the foundation for subsequent “big ideas” lectures. His dynamic style of delivery and humor (at one point he references his favorite nudist colony in New Jersey being destroyed by the effects of climate change), and the production values that accompany his insights really help to place the viewer in a virtual classroom. The shots of bustling cityscapes, sprawling slums, aging couples going for a stroll, and mothers leading their babies past thatched huts help remind you what demography is all about: people.