Joel Cohen: An Introduction to Demography (Malthus Miffed: Are People the Problem?)

Joel Cohen: An Introduction to Demography (Malthus Miffed: Are People the Problem?)



My name is Joel Cohen
I’m Professor of Populations at the Rockefeller University and at Columbia University in New
York City.   My background is partially in public health
and partially in applied mathematics. WHY SHOULD YOU STUDY DEMOGRAPHY?
Why should you consider taking a course in demography in college? 

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 into the United States and in some cases, out,
into Europe and out between rural areas and cities.

You need to understand as a citizen
and as a tax payer and as a voter what’s really behind the arguments.  

INTRODUCTION
TO PROBLEMS IN DEMOGRAPHY

I want to tell you about the past, present and future of
the human population.  So let’s start with a few problems. Right now, a billion people
are chronically hungry.  That means they wake up hungry, they’re hungry all day and
they go to sleep hungry.  A billion people are living in slums, not the same billion
people, but there is some overlap.  Living in slums means they don’t have tenure in
their homes, they don’t have infrastructure to take the garbage away, they don’t have
secure water supplies to drink.   Nearly a billion people are illiterate.  Try
to imagine your life being illiterate.  You can’t read the labels on the bottles in
the supermarket, if you can get to a supermarket.  Two-thirds of those people who are illiterate
are women and about 200 to 215 million women don’t have access to the contraceptives
they want so that they can control their own fertility.  
This is not only a problem in developing countries; about half of all pregnancies are unintended.
So those are examples of population problems.  
DEMOGRAPHY AS A TOOL FOR SOLUTIONS Demography gives you the tools to address
and to understand these problems.  It’s the study of populations of humans and non-human
species that includes viruses like influenza, the bacteria in your gut, plants that you
eat, animals that you enjoy or that provide your domestic animals.  And it includes non-living
objects like light bulbs, and taxi cabs and buildings because these are also populations.
 And it includes the study of these populations in the past, present and future using quantitative
data and mathematical models as tools of analysis.  
I see demography as a central subject related to economics, to human wellbeing as in material
terms; related to the environment, to the wellbeing of the other species with which
we share the planet; and the wellbeing and culture which affects our values and how we
interact with one another. 

WORLD POPULATION: THE PAST
The key fact you need to remember, is that since the inventions of agriculture between
6,000 and 14,000 years ago, the population of the earth, the human population, has grown
1,000 fold from approximately seven million to nearly seven billion this year.  Put three
zeroes on the end of seven million, you get seven billion.  
Over the same interval, the earth has not gotten any bigger.  The continents haven’t
expanded 1,000 fold or at all.  The oceans are the same size as they were before.  The
atmosphere is the same size as it was before.  So the question that concerns a lot of people
and me is whether the impacts that seven billion people or more in the future will have on
the earth will endanger, will threaten our own well being and the well being of other
species on the earth.  We know that humans have already caused the extinction of many
species.  The question is, is that going to come back and bite us, and if so, in what
ways?   Demography provides us with a reliable way
to imagine and to reimagine the future.  So let’s get down to some nitty-gritty details
here.   About 2,000 years ago, there were roughly a quarter of a billion people on the
planet.  Today, there are almost seven billion. More than six-seventh of the growth since the beginning
of humans 50,000 years ago has occurred in the last 200 years.  
To go from a quarter of a billion to half a billion took 16 centuries.  So we reached
about half a billion humans about 1600, more or less.  The population of the earth, the
human population, if it were growing exponentially would go from a quarter billion to half in
16 centuries and from half to one in another 16 centuries.  
What actually happened was that the human population of the earth reached a billion
around 1800.  Why?  Because of food stuffs that came from the New World to the old; notably
potato and corn or maize.  And because many of the people who were overcrowded in Europe
went to America where there were fertile and unoccupied lands to use.  So the East/West
exchange, the Columbian exchange across the Atlantic liberated population growth in the
European sector, there was a similar development in Japan, an acceleration of population growth
around the same time.   In 1800, the Industrial Revolution began and
the population doubled from one billion to two billion by 1930, 1927, we don’t know
exactly.  Why don’t we know exactly?  Because we didn’t have censuses that covered the
whole world at that time.  So it’s a retrospective guess.  
So our doubling times went from 1,600 years to 200 years, 1600 to 1800, to 130 years,
1800 to 1930.  The next doubling from two billion to four billion took only 44 years,
1974. 

So for the
last 2,000 years at least, except for the
Black Death in the 14th century, the population growth rate was going up, up, up, up and around
1965, it began to decline.  
So in absolute terms and in percentage terms, the number of people we are adding to the
planet has begun to slow.    FERTILITY IS THE KEY TO UNDERSTANDING HUMAN
POPULATION

Since 1950, humans have made the swiftest, voluntary change in reproduction
in human history.  Around 1950 the average number of children per woman, per lifetime
was very close to five.  Today, the average number of children per woman is about 2.5
or 2.6.  In other words, billions of people have changed their reproductive behavior to
lower the number of children born in a lifetime from five to two-and-a-half, but not everywhere.
  In Sub-Saharan Africa, the decline has been
much less.  From perhaps 6.6 children to 5.1 over the half… the second half of the
21st century.  To understand the consequences of this fall to two-and-a-half children per
woman, you need to know what is meant by replacement level fertility.  
So I am going to introduce that by telling you about the theory of bathtubs.  A regular
bathtub with no stopper.  So two things happen with a bathtub with no stopper.  Water comes
in and water goes out.  And you can see intuitively that if the amount of water coming in per
minute exceeds the amount of water going out per minute, the level of water in the bathtub
is going to go up, and if the amount of water come in per minute is less than the amount
being drained out, the level in the bathtub is going to go down.  So the amount of water
coming in that just matches the amount going out keeps the level of the bathtub steady.
 Okay?  That’s replacement level bathtub water.  

Now, water coming in corresponds
to births to the earth.  And water going out corresponds to death.  And the level
of the bathtub corresponds to the total population size.  So, if the number of births just matches
the number of deaths, the population stays steady and that’s the replacement level
of fertility.  

Now, you’re asking yourself, what is the replacement level of
fertility?  The answer is, it’s about 2.1 children per woman.
There has been an amazing transformation in the distribution of fertility across the world.

In
2003, this was not in any newspaper anywhere, but it was a very important event.  In 2003,
half of all the women in the world were having replacement level or less.   And now more
than half of humanity lives in a country at or below replacement level fertility.  It’s
the first time in human history that this has happened.  And it’s important.  But
you remember that the total fertility rate, the average number of children per woman is
at 2.5, not 2.1.  And that’s because on this curve, the green curve, the folks with
high fertility are further to the right of the red line than most of the folks with low
fertility are to the left.  So the average is skewed to the right.  So we still have
a growing population.  But this change is continuing and how fast it continues is something
that you as voters, as potential scientists, as citizens will influence by what you choose
to do about the 215 million women who have an unmet need for contraception.  
WORLD POPULATION: THE PRESENT So much for the past, let’s go on to the
present. This is a population pyramid.  It is one of the basic descriptive tools of demography
and you should understand what it is.  Let’s start with the left side of the picture.  
The horizontal axis, the width of the bar tells you how many people there are and the
vertical axis correspondence to age group.  So the lowest bar is for people aged zero
to four with males on the left and females on the right.  The next bar is people age
five to nine. The top bar is 95 to 100.  And what you see is that in the rich countries,
there are about as many people aged, let’s say zero to four as there are aged 85 or 90,
but it’s basically a slender column.   Now compare it with the age pyramid for the
poor countries.  The base of the pyramid is enormous compared to the number of elderly.
 So there are many more workers to support the elderly, per elderly person.  The width
of the bar, again is the number of people, so in the ranges from five to 14 of five to
19, that’s the school age population.  It means that the challenge of educating those
children is much greater in the developing countries than it is in the rich countries
because those bars keep getting wider as the developing countries pump in more children
at the bottom of the pyramid and the age groups move up with time as they get older. And so
the larger school age population is followed 10 years later by a much larger military age
population.   So if you look at the age groups 19 to 30
or 15 to 30, whatever the legal ages or illegal ages are for fighting, you can see that the
potential military force in the developing countries vastly exceeds that in the rich
countries.  It doesn’t mean it’s military power for them, it means they can afford a
military engagement in a way that the human resources of the rich countries make very
difficult, increasingly difficult.   So where is the growth going?  The demographic
growth is happening in the countries that can least afford to deal with the additional
population.   What’s the average income?  The reason
we call a rich country as rich is that their average income is about $32,000 a year per
person and in the poor countries it is about $5,000 a year.  
What fraction of people are living on less than $2.00 a day?  Nobody lives on less than
$2.00 a day in the rich countries and 51 percent, just about half in the poor countries.  In
other words, about 3.5 billion people on our planet are living on $2.00 a day or less.
So you might ask yourself, if things are so bad there how is it that their population
is growing so rapidly?  And the fact is that the difference in death rates is much smaller
than the difference in fertility rates.  So even though a higher fraction of children
die before they reproduce, the average number of children that people have when they do
reproduce in the poor countries more than compensates for the increase in the death
rate.  So that’s why we have rapid population growth at the same time that we have high
fertility, high mortality because we had even higher fertility.  
The global economic inequality means that the most rapid demographic growth is associated
with the people who have the least means to take care of the children that are born and
the people with the greatest need for reproductive healthcare and services have the least means
to afford it.   It’s an important general question, How
does the rich world benefit from the prosperity and development of the poor world?  There
are lots of different answers you can give.  One is, purely economic.  Richer people
in China and Africa will buy more American music CD’s and more movies and more software
and more high tech engines from General Electric and more products because they have more means
to buy.  So that’s one kind of an answer.  
A second is public health.  There are millions of flights in both directions from the poor
countries to the rich countries every year. And the microbes don’t know about passports.
 And they cross from Bombay or Mumbai to New York just a fast as they go from New York
to Mumbai.  And when there are outbreaks of drug resistant tuberculosis, those can
travel around the world and they pose a danger to me and to you guys.  So we have an interest
in the health and well being.  A direct, personal interest in the health and well-being
of people in poor countries. WORLD POPULATION: THE FUTURE
So now we’ve talked about the demographic past, and the demographic present.  And next
we’re gonna talk about the demographic future.  
Woody Allen said, “Eternity is very long, especially near the end.”  So, we’re
not going to talk about eternity.  We are only going to talk about the near term future.
 How much of the future is relevant to you?  Well, according to the United States Life
Tables, published by the National Center for Health Statistic.  An 18-year-old in the
United States in the year 2011 has a 91 percent chance of surviving to 2050, 91 percent.  Based
on survival rates in 2006.  If you behave wisely and if economic and medial progress
continues, you have at least that good a chance of making it to 2050.  So we’re going to
talk about the world from now to 2050.   I can say with confidence that four things
will happen over the next 40 years or so.  The world’s population will get bigger.
 It will grow more slowly.  It will be older in the sense that the fraction of older people
will increase dramatically and it will be more urban. And I’m going to go through
each of those four to explain some of the details.  
What we don’t know too much about is what will be the future of migration, the future
of household structures, and the future of families.  We have some ideas about that,
but that’s relatively less certain.   THE FUTURE OF THE WORLD’S POPULATION : BIGGER
This graph shows four different curves of the history and future population out to 2050.
 At the top, the curve shows the anticipated population if fertility remains at the level
it is today and there’s no further decline in fertility.  That’s called the Constant
Fertility Assumption.  And it shows that the world would go to about 11 billion people
by 2050.  However, if fertility drops as it has dropped in the past, the medium projection
of the U.N. Population Division is that population would rise to about 9.1 billion by 2050.  So
that’s a difference of two billion.  In other words, we’re counting on a continuing
decline in fertility to lower the population size by about two billion by 2050.  

What
we do between now and 2050 will have a huge impact on how difficult it is to feed, house,
shelter, educate, and provide health for the billions of people on the planet in 2050.
 It will affect an enormous range of human problems.  
It’s possible that population growth would end before 2100 depending on the choices we
make now.  What choices am I talking about?  Choices like, educating women, providing
credit to women in countries where women are not now allowed to have credit. Providing
reproductive healthcare so that women are not forced as they are in some countries to
have children when they don’t want to.  Raising the age of marriage so that 12-year-olds,
13-year-olds and 14-year-olds aren’t put into marriage.   There’s a lot of things
we can do to raise people, including even women, raise people’s control over their
own lives.  And we should be doing those things. 

I am not trying to persuade
people not to have children.  I think that is nuts, but I am trying to persuade people
to have children that they can take care of and do well for and to focus on quality of
children rather than numbers.  And, I view demography rather broadly so I think you also
need to know how your body works, how contraception works, what’s more reliable, what’s less
reliable, what are the factors that affect contraception and how to take care of your
own reproductive health and to help your children take care of their reproductive health and
your friends and your family. THE FUTURE OF THE WORLD’S POPULATION : SLOWER
GROWTH So the first fact about the future is that
the population is going to get bigger and the second fact is that the population is
going to grow more slowly depending… the slowing will depend on what we do now.   
By 2050 in the medium projection from the United Nations Population Division, the world
will be growing by 31 million people a year.  
What’s it doing now? It’s growing by 76 million people a year.
In the poor countries, the population will be growing by 32 million a year while in the
rich countries; the population will actually be declining
by a million people a year.  Already today in 2011, population is declining in more than
50 countries.  Not well-known. What’s happening here is a shift in childbearing
desires and action from quantity to quality as people urbanize, as people get educated,
as wealth improves, people are making greater investments in a smaller number of children.
  THE FUTURE OF THE WORLD’S POPULATION : OLDER
So we’ve talked about population size, growth rate, slowing.  The next is aging.  

So
by 2050, there will be about three times as many elderly as children.  This is the first
time in human history that the elder population has outnumbered the young population.
So what?  Well, aging affects energy demand.  So even if you are interested in the environment,
you need to know about the age structure of populations.  Older householders spend, at
least in the United States, India and China, the three countries where it’s been studied
in detail, spend more than younger households measured by the age of the head on utilities
services and healthcare. Utilities are the most energy intensive part of the household
budget.   That’s not the only reason to care.  The rise in the fraction of elderly
poses an increasing challenge to a relatively reduced number of workers.  And it’s possible
that the well-being of elderly people could improve, if they’re educated or could get
worse if they are warehoused in old people’s homes.  
We know for example, that people who are educated in their youth have much lower disability
when they get older.  And in fact, disability rates at any given age in the United States
have been dropping by about one-and-a-half percent per year for the last 25 years.  So
there are far fewer disabled elderly now than there used to be.  That’s the meaning of
60 is the new 40, 50 is the new 30. People are healthier at older ages.  That’s the
result of investment in education in youth.  So, there are policy implications for a
rising aged population, we better invest in educating people when young.  
THE FUTURE OF THE WORLD’S POPULATION : URBAN And the last of the four topics is cities.
 And I’m going to give you a very simplified and boiled down demographic history of the
first half of the 21st century.  In 2000, you could divide the world into two equal
parts; half rural and half urban, about three billion rural and three billion urban.  In
2050 the rural population will still be at three billion and the urban population will
have doubled from three billion to six billion.  That’s a simplified history.  All of
those additional three billion urban people will be in poor countries.  
The equivalent of a city of one million will have to be built every five days from now
to 2050 and all of them in poor countries.  

So what’s the consequence?  What
is this massive shift towards urbanization mean?
If we under invest in cities, we can go from a billion people living in slums today to
four billion people living in slums.  And if we invest in the cities, if the real estate
companies realize the opportunities, the incredible demand that people have to live in decent
housing, we could reduce the size of the slums.  So, I cannot give you a deterministic picture.
 I can tell you what would be awful. We could have infectious diseases rampant.  We could
have warfare in the cities.  We could have disorder, but that’s not necessary.  
We could have clean water supplies; we could have security for people in their houses.
 That doesn’t get as much news attention, but the point I want to make is, we have choices
about the future of cities and many things about urbanization are positive.  And I want
to tell you a few of the things that are positive.  Not because they’re automatic, but because
they are positive in fact and because we can enhance the positive.  
Compared to rural areas, urban areas have lower fertility rates.  Why?  I’m a woman
on the farm.  You might not think so, but I am… okay.  I’m a woman on the farm.
 The more children I have, the more help I can have in collecting the water, collecting
the fire wood and tending to the goats and sheep.  As soon as I move into a city, those
children convert from an asset to a liability.  I have to buy them clothing.  I have to
send them to school.  There are school fees, the apartment is too small.  The incentives
completely shift direction.  Urbanization makes people want to have fewer children.
  Cities also have higher usage of modern contraception
and lower unmet needs for contraception.  Why?  I am a woman; you might not know it… I
don’t have to walk 15 miles to the nearest health center and be exposed to the inspection
of my husband’s friends when I go in for contraception.  No.  When I’m in the city,
I just go around the corner and it’s anonymous.  So, urbanization brings many features of
liberation as well as changing the incentives.  
Cities concentrate economic productivity.  Eighty percent of the world’s gross domestic
product is produced in cities, although there are only 50 percent of the world’s people
in cities.  Cities generate cultural assets, educational resources, public health resources,
medical care and they can promote energy efficiency.  
Let me give you an example.  This graph shows the passenger transport, carbon dioxide per
person. The denser the city, the lower the amount of carbon dioxide per person.  New
York City is reported, according to the Mayor’s office, to have less than one-third the carbon
dioxide emissions per person of the U.S. average.  People take the subway, people ride the
bus.   Cities also have hazards.  Many cities are
built along coastlines.  Coastlines are where the continental plates of the oceans collide
with the continents.  That means they are prone to earthquakes.  We just had the big
example in Japan, but it’s true all around the world.  The Ring of Fire around the Pacific
Ocean coincides with where the cities are because cities are coastal.  A lot of the
world’s urban people live near the coastline and that’s where the subduction zones are
in California.  So cities are vulnerable to rising sea level, to coastal storms, cities
concentrate people so they’re vulnerable to infectious diseases, water supply attacks,
and cities are excellent targets for military and terrorist attacks, as we know in New York
City and many other cities.   It used to be, battles were fought on battlegrounds.
 No more.  They’re fought in cities.  And that will increasingly be the case as cities
concentrate assets.   This is New York City as it is now.  The
red zone will be underwater if the water level rises by one meter on the average.  One meter
is probably more than we’ll have in the next 50 years, but could easily happen by
the end of this century at current rates.  Now, a six meter rise would happen if the
Greenland and Antarctic ice masses melted.  Six meters is about 20 feet.  And that
would be a catastrophe in many respects including for me, there’s a little place over here
in New Jersey which is my favorite nudist colony. And it would be completely underwater.
 So that would be a terrible thing
to happen.   Urban growth could affect the food supply.
 Right now, cities occupy three percent of the land surface of the earth.  The land,
the arable land, the land where we can grow food well is about 10 or 11 percent of the
land surface of the earth.  It’s not surprising that many cities are smack in the middle of
the best arable land because that was where a food surplus could be easily produced without
having to ship the food.   Now, if cities are going to double, we have another choice.
 Do we double the area from three percent to six percent and eat up our arable land,
literally or do we double the density and keep the areas of the cities constant at three
percent. This is a choice for the future and it depends on zoning and culture and real
estate developers and economics and choices that we make as citizens.  

CONCLUSION
– FOOD: THE WORLD IS RUNNING OUT OF RESOURCES TO SUPPORT ITS GROWING POPULATION
How do we address the problems that we have.  
There are three kinds of solutions that people have put forward; bigger pie, fewer forks,
better manners.  The bigger pie people say we should use technology to increase production.
 The fewer forks people say, we should use contraception to reduce population growth
and we should consume less material products.  And the better manners people say, we should
eliminate violence, inequities between men and women, inequities between rich and poor,
inequities between young and old.  We should eliminate rational subsidies and just make
things work more efficiently.  Get rid of corruption.  
We need all of those and I took a few years to try to figure out what’s my best way
to support those three strategies, all of them. And I came to the conclusion that the
best response would be to educate all children, boys and girls, well for 10 to 12 years, high
quality, primary and secondary education.  I realized there is no chance of educating
people if their brains haven’t been fed adequately, in utero and after birth, especially
for the first three years.  

So I am now moving around to working on the problem
of getting food, adequate, good food, to pregnant women, lactating women, and infants up to
the age of three because there are many countries where by the time a child gets to school,
it’s too late the brain has lost its capacity to learn.  
It comes back to my ecological interests in food.  You can’t educate without a brain
that works. So now we’re talking about food.  I started
this conversation saying that there are a billion hungry people, chronically hungry.
 I want to come back to this.  We depend on other species.  Here is a list of what
other species provide to humans.  And I’m going to read the list because it’s important.
 Food for people, feed for our domestic animals, fuel, biofuel for example, and wood to burn,
biomass. And in many countries people burn dung.  The waste products of animals.  That’s
an important source of fuel.  Fiber, so we depend on trees for many paper and other products.
 Fascination, we love to go to the zoo and see animals.  We love to see wildlife.  When
people go out in nature, they’re thrilled if they see a deer or some other kind of wildlife.
 In fact, in Central Park, the German tourists are thrilled to see squirrels.  We find animals
fascinating.  Pharmaceuticals, most of our drugs are natural products tuned up to serve
human needs.  Animals provide transport, they carry people places.  They provide traction,
they pull plows, they pull carts.  Other species provide symbioses.  I’ve talked
about the animals, not the  animals, the bacteria that live in our guts.  And they
provide infection.  They can cause disease.  
So the question I want to address now is can we grow enough food to bring us to 2050 without
catastrophe?  These are data from the Food and Agricultural Organization in Rome.  They
are estimates of the number of people in the world who are chronically under nourished
day after day.  The current estimate is about 925 million people.  That’s nearly a billion
and it is higher than the number has been in the last 40 years.  Ninety-eight percent
of these people live in poor countries.  Not only poor countries.  Here is something that
shocked me and I hope it will shock you.  At some point during 2009, 17.4 million U.S.
households, one household in seven in the United States, lacked enough money and other
resources to provide food for all members of the household.  
The current level of food insecurity in the United States is higher than it has been since
the USDA started collecting the statistics by sample surveys in 1995.  We are at an
all time high of hunger in this country.   So the question you should be asking yourself
is, well aren’t we growing enough food? What’s the problem?  
We’ve got seven billion people and there are a billion of them hungry.  The answer
is, less than half of the grain that we grow goes into people’s mouths.  Divide the
world’s grain into six equal pieces.  One piece we use to make biofuels, starches, for
seed and other industrial uses; plastics.  Two-sixths, we feed to our domestic animals
of the rich people, those who have the means to afford those animals and meet products.
 Less than half, the other three-sixths goes directly into human mouths.  We could be
feeding 11 billion, but we only feed half of that amount, 5 ½ billion into human mouths.
  We put machines and animals in line before
people who don’t have money to express demand in markets.  Hunger does not fit into our
economic theories.  It’s economically invisible because people who are very poor, remember,
half a billion are only living on $2.00 a day or less.  People who are very poor can’t
enter the market and plunk down their cash and say, “I want that.”  They are invisible
economically.  So my hunger does not affect your costs for grain.  This is a problem
with our economics.  And it’s a reflection of our values. 

CONCLUSION – WHAT’S
THE SOLUTION?   So, here’s Joel’s formula for how to solve
the world’s problems.   Well, population; let’s go at it with all
hammer and tongs.  Eliminate all unintended pregnancies and educate all children to give
people control over their bodies and over their own lives.  
Economics, open credits and markets to small farmers.  A majority of the world’s farmers
are women.  They are the ones out in the field actually doing the work.  Eliminate
perverse subsidies in rich countries make it very difficult for poor farmers to enter
markets because they lower the price in artificial ways.  And let’s raise the incomes of the
poor. 

Environment.  Use the best farm lands for farms and internalize the external
costs of agriculture.  Get rid of the pollution and use chemicals in a way that doesn’t
damage the environment.   And fourth, promote healthy diets and value
adequate nutrition for every person.  I would add one other thing under this culture question
and that is, we need to fund more research in agricultural productivity for the crops
that matter in poor countries.  Not only for the industrial craps that fund our biofuel
habit, but for the crops that provide food to the poor.  
CONCLUSION – SUMMATION

When you walk away from this conversation, I hope that you’ll
remember that population interacts with economics, the environment and culture so that you immunize
yourself against people who will try to sell you an overly simple bill of goods.  And
there are a lot of people.  There are people who say, “Demography is destiny,” and
all we have to do is get a contraceptive in every pot and we’ll solve the world’s
problems.  That’s wrong.   And there are people who say all we have to
do is get the market right.  Let the market take care of all the prices.  In my view,
that is equally wrong and much more dangerous.  There are people who say, “It’s only
a matter of law and getting the laws right.”  Yeah, but it’s also a matter of technology
and contraception and economics.  And there are people who say, “Forget about the people,
let’s just save the environment.”  I don’t believe that because I’m a human
being and I value other human beings.  We’ve got to get all of these things working together
and the environment can be on the side of human well being because poor rural people
depend directly on the environment for their sustenance.  If they want to have a sustainable
sustenance, they have to have a sustainable environment.  

Demography makes it possible
to imagine and to re-imagine the future.   I’d encourage any freshman, sophomore, junior,
senior, adult, high school student—I’m not age prejudiced—anybody who wants to
do three things to consider demography.  It’s not the only field that offers these attractions
but it does offer them in spades.  It’s really very attractive.  First of all, demography
gives you tools and analytical perspectives to understand better the world around you.
 That’s understanding.  

Secondly, it gives you equipment to solve problems mentally.
 It’s mentally exciting; you really have to use your noggin, and if you’ve got one
use it or lose it.  So it’s use it.  And third, it is the means to intervene more wisely
and more effectively in the real world to improve the wellbeing, not only of yourself—important
as that may be—but of people around you and of other species with whom we share the
planet.  

So it prepares you to go out and do something that’s worth doing for
a larger good than only yourself.  So there’s an old saying, “If I am not for myself who
will be; but if I am only for myself what am I; and if not now, when”?  So now is
the time.  Pull up your pants and get to work.

Thank you.


100 Comments

  1. Carbonic Oyster says:

    If Apple made Ethnic Cleansing

  2. Łukasz Wybrańczyk says:

    This was absolutely fascinating!

  3. swcoast says:

    Now there is an ''unmet need for contraception'' once the developed world have had their boom time. The developed countries are only doing what the developed world did all this, and just because the resources are running out (interestingly, predominantly due to the consumption level of the western nations – see US's consumption alone!), there must be 'extermination' of people. Back then it was a sign of wealth and power to have many children, and now that it no longer suits the ideals of the western world, now there is a need to exterminate humans like rats. Pretty arrogant. Maybe if you cut your consumption levels then the rest of the world won't need to drastically cut their birth rates. But I guess giving up riches is too much to ask for; rather ask the poor folks – who have nothing else but the joy of their children – to give up the one thing they can probably contribute to a future in this world.

  4. swcoast says:

    Quite presumptuous to assert that women in those countries are forced or making uneducated choices about having children. Ever thought that procreation is perhaps just part of their culture there? Not all have replaced the use of their reproductive organs for something purely selfish and pleasure-seeking; some use it for its biological function. Also, w.r.t. raising the age of marriage, what about the all the underage girls getting pregnant over here? Don't they do the same? At least over there these children are brought into a family, not a life where the mother is probably a single parent, and not even ready at that, and the father probably no longer around. Again, it is very arrogant and dangerous to assume all the changes need to be made by those cultures .Remember, if there are 7bn people on this planet, then chances are that JUST maybe not ALL those people share the same views. It's pretty arrogant to assume your views must become their views now that our resources, which we in the west have outstripped, are becoming ever scarcer. Why should they now control birth? How about we control the use of these scarce resources – just think how much energy it costs to light up Las Vegas in a single year. I bet in those parts of the world they don't even consume that level of energy in their whole country. I wonder what the real agenda is when women are too young to get married, but at the same time, they are not too young to sleep around and get pregnant like we hear a lot of in the UK – e.g. a 10 year old father…remember that one?! 

  5. swcoast says:

    28:40 Once more, the assertion that birth control is liberation, as though birth were now exploitation of women too. Is that not the biological role of the female in any species? Why the assertion these are women in caves being forced to get married and have children – this Western view of the developed countries that he implies – and there is a strong undertone of this throughout – is really offensive. Please change your tone. It's detracted from an otherwise invaluable lecture and resource. The way we in the west are objectifying women as a purely sexual object is far more exploitative and oppressive. It's an old-fashioned view that these women are being policed by their men. Perhaps they actually want to have children. Like I said, in some cultures – as it was here too in previous eras – children are a sign of wealth, particularly when you have no material wealth. Moreover, it's the way all living things ensure the survival of their species. Nowadays it's become more objectionable for a woman to be married and have children than it is for two man to have a civil partnership, or even – as of late – get married. Now that is fucked up when you start twisting nature's laws. Realise that without procreation, irrespective of the demographic time bomb we're now facing, we would not have survived as a species all those years ago to become what we are now. I would have thought that would be obvious in a part of the world where we admire the concept of evolution.

    The solution to the problem is not in changing the innate and biological behaviour of humans, or females, in the sense of limiting their birth and masquerading it as 'women's liberation', but to look towards devising innovative strategies for sustainable resources in place of the vastly diminishing fuel and energy sources that, particularly we in the West, have consumed during our booms. Its pig-headed to interfere with other cultural beliefs and societal life just because we have tired out of that idea and exhausted the worlds resources. If that were the case, why didn't we 'liberate' our women when there was a boom – because perhaps we didn't realise the effects on our resources of this demographic scenario, not because there is anything inherently wrong with marriage and birth.

  6. swcoast says:

    34:00 Awesome.
    43:00…very cleverly put.
    All in all, great presentation. Thanks a lot!

  7. solasagusdochas says:

    Great insight on our Shared global past, present and potential futures in how human activity directly shapes regional cultures and associated stresses flowing on to our shared environments. Informative and well executed demonstration of benefits of demography for predicting future demands on society. Well done.

  8. Just Another Ben says:

    His way of lecturing would be great in a classroom, but it's annoying in a video.

  9. Radu Rusanu says:

    Don't you just love the way he talks? I wish this guy could replace all of my teachers.

  10. Tariq Hakim says:

    "I am a woman… you might not know it but I am."

    "There is a little place over here in New Jersey which is my favourite nudist colony, and it would be completely underwater. So that would be a terrible thing to happen."

    "Pull up your pants, and get to work."

    This guy is hilarious

  11. ProjectORION89 says:

    The developed world is underpopulated, and the developing world is overpopulated. We should focus on depopulating the developing world.

  12. Thor says:

    People should recognize that this demagogic fear-mongering has existed for 1000s of years. This anti-humanist rhetoric is how the oligarchs try and control the population

  13. f lotars says:

    30:37 hihi

  14. Udai Muhammed says:

    nice info to know .. you got me very interested in the subject professor !

  15. TheyCallMeNewb says:

    I found this positively fascinating, though demography is not, nor do I imagine that it ever would be my field. Inspired!

  16. Magic Television says:

    We are all screwed…

  17. Stacy Clarkson says:

    Productive peoples need to have a very positive birthrate,if not collapse is inevitable…My wife and I have 7 children ages ,27,23,21,20,18,and IVF twins 5 years old…:)

  18. carlsosj qaniiuin says:

    This is what got me interested into Eugenics. Great video

  19. garybsg says:

    IN 1970s  I WAS IN COLLEGE AND ALL THEY TALKED ABOUT WAS POPULATION EXPLOSION AND MASS STARVATION WHICH WAS TO HIT AMERICA BY 2015

    NOW 45 YEARS LATER, WE SEE THEY 100% WRONG AND TODAY WORLD WIDE POPULATION DECLINE IS THE BIGGEST PROBLEM. LEFTWING BULLSHIT

  20. The Kid says:

    Peace at all costs, what a joke.

  21. The Kid says:

    This guy wants you all to sleep in coffins.

  22. Jack Nugent says:

    These videos are literally the most helpful and informative videos on the internet. I hope Big Think can make more of them.

  23. Kristin Legault says:

    This documentary is incredibly interesting and helpful, and I am looking forward to learning about demography throughout my university studies.

  24. Isak Mohamed says:

    i like his glasses> 

  25. Kastanje47 says:

    What? "My favorite nudist-colony?" 

  26. Rhys Dent says:

    Where's Ethan?

  27. Sahul says:

    "Sometime in 2009, 1 in every 7 US household lacked enough money or resource to buy food for all family members"…shocking indeed

  28. Nick Dantae says:

    Every Useful

  29. Oscar Santiago says:

    Estoy aquí porque me encargaron ver este vídeo de tarea.. y me gusto 😀

  30. lucy diamonds says:

    just go vegan! problem resolved

  31. Joshua Tang says:

    cant stop looking at his eyebrows 

  32. Budget Media Waley says:

    Not all coastal cities are earthquake prone

  33. Nebu Losa says:

    "Elderly use more utilities." Could it be because they spend more time at home? What happens if we add what younger people use at home and at work?

    "Only half of the grain produced is eaten by people. We could be feeding 11 billion." This is terribly failed reasoning. The population will continue to increase as the availability of food grows, and we will get to a point where we can't produce more food. So might as well stop growing now. Make contraceptives universally available.

  34. John Taves says:

    The current state of the art with population scientists is unconscionably bad.

    200 years ago Malthus pointed out that populations grow exponentially and food subsistence at best will grow only arithmetically. From this he concluded that this means that there will always be large numbers of people suffering from poverty. He was fundamentally correct, but scientists ever since have focused on the faults of Malthus statements, like the ridiculous notion that subsistence production increases at most arithmetically, and failed to comprehend the nugget of truth. (I don't think Malthus really comprehended the nugget of truth either.)

    The nugget of truth that Cohen and generally all scientists since Malthus has over looked is that reproduction ATTEMPTs to grow the population at an exponential rate. The underlying force of population IS an exponential function. Subsistence production is limited. We have no clue how high we might raise it and we know it has been raised in the past with farming, fertilizers, refrigeration, trucking, etc…but a history of rising subsistence production should not lead us to assume it has ever rose as fast as our population was attempting to rise given the number of babies we averaged.

    We should assume that the population is always at the limit, and we should figure out what "at the limit" means. It does not mean wars, famine and vice, as Malthus suggested. It means some people will die of starvation. Specifically, children must die of starvation when we are at the limit. Notice that there have always been groups of people suffering starvation related child mortality.

    Think about it. There is no excuse for human starvation on this planet. The only thing that stopped the people that died of starvation from getting the sustenance that naturally grows on this planet was other people.

    What is it going to take for our population scientists, like Cohen, to admit that the relentless attempt at exponential growth that averaging more than 2 babies has always generated, is killing?

  35. turningundead says:

    some hope is coming. 
    indias birth rate in half of its regions have fallen below replacement level. pakistan has gone from 3.8 children in 2010 to now 2.8 children in 2014. Africa is the only continent today that has a high birth rate.

  36. John Taves says:

    At 10:00 in this video, Joel Cohen provides a bath tub example to explain the concept of replacement rate. This example is stunningly bad. He should have drawn the bath tub full of water. Births are flowing in so fast that the death drain cannot keep up and water flows over the top.

    Water (births) is flowing into the tub so fast it is overflowing (killing). That is the reality in this world and our population scientists are ignorant of this.

    There is only one excuse for a population expert like Joel Cohen to draw that analogy. He simply does not know the fundamental reality that births relentlessly drive our numbers to the limit and that births are killing.

  37. Michael Lindsey says:

    The only way to raise standard of living to stop the birth rate is through free markets without the oppression of corrupt governments upon their people. Freedom raises living standards, Period. No country on Earth has true economic freedom, including the US, but the information shows that the more economic freedom that people have, the higher the standard of living and the lower overall birth rate. I think that this video confirms this……even if it was not actually the intent.

  38. Gerard Seegers says:

    Ziet er niet goed uit voor de Christenen,dus meer oorlogen.

  39. Harrison Bootes says:

    Shout out to Ms.Perez

  40. Derrick McCoy says:

    omg you are boring

  41. CP Johnson says:

    Absolutely amazing!

  42. Brian Diner says:

    Shout out to Mrs. Lopez

  43. Sabir Hussain says:

    one has to stand in line for every thing every where….which was not visible a decade ago…the queue keeps getting frustratingly elongated….
    from the point i see it everybody who chould do something about it…either dosent acknowledges the problem or is benefitting from it…

  44. Abdul Rehman says:

    thousands of thanks sir sharing your knowledge about demography

  45. Ron Micci says:

    This is an excellent and instructive video, but does not take into account what has become the dangerous but important third rail in social studies — dysgenics. Generally speaking, the populations with the lowest IQ have the highest rates of fertility. How does this upset the demographic applecart? It has been estimated that only parts of Africa will be achieving or exceeding their birth replacement level by the year 2050. And not even early childhood nutrition has a substantial LASTING affect on IQ. See "Dysgenics" by Richard Lynn, a vitally important book.

  46. FloodedTyphoon says:

    Replacement level fertility is some metal shit. It's a bathtub being constantly fed human children and letting out the souls of the deceased.

  47. RyChampion says:

    Shout out to Dr. Strong!

  48. John Dolinar says:

    Everyone should be required to watch this

  49. blownspeakersss says:

    This is very much related to economics. In fact, the demography courses at my university are within the economics department. Very interesting stuff.

  50. Nadia Shireen Siddiqi says:

    I think contraception is more easily available to rural areas in Pakistan and Bangladesh than in cities.

    The corner drug store needs a prescription for contraceptives to my knowledge and even proof of marriage. I don't think it's in the legislation but it's definitely in the culture.

    Anonymity and privacy in cities is a dead myth, especially in apartment buildings and housing complexes.

  51. Michael Kossin says:

    Things are even worse than Malthus predicted, because he was looking at things on a local scale. He didn't imagine that we could cause worldwide ocean fish populations to collapse, that we'd start using so much water that deserts started growing, that we'd start clearing rainforests at one acre per second for new farmland, or that we'd be able to change the climate of the whole world. Oh, and I don't think he could have imagined the worldwide extinction event we'd start either. As for the numbers game this video is playing, they seem to be using the word "rate" to refer to population growth per unit of time per person. They added the last two words to the actual definition of "rate" to make themselves feel better.

  52. Eveque Murwanashyaka says:

    well

  53. rachcliffe says:

    you should be the pesident of United States

  54. Luciano Almeida Filho says:

    A small misconception said by him: "Coastlines are where the continental plates of the oceans colide with the continents" not always true. As you can see in the map shown at 29:45 not all coast are where tectonic plates meet. Example of this is brazil where there are almost no earthquakes

  55. mclarenf45 says:

    The obvious fact that was missing: food production, as long as excess food is reaching to people they will expand, so bringing more food will only increase population.

  56. David Esteban Rojas Ospina says:

    This is amazing, i'm currently studiying sociology but as soon as i finish i'll go for a master degree in demography!

  57. Delia says:

    How to fix overpopulation:
    1. Don't have kids
    2. Condoms
    3. Don't have kids

  58. Lynn Moore says:

    makes sound sense!! True, based on data from undernourished and provisioned countries. Shocking that so many in the U.S. (1 in 7) households unable to properly feed their families…Does anyone have a more convincing theory as to reversing these issues? Why is it that when someone proposes actionable, and deductively reasoned proposals, that naysayers always rebut without offering a better or alternative solution? I say shut up or put up!!

  59. Maria Mederos says:

    It's not simply a matter of family size, but of lifestyle and consumption. I know people who live by themselves, but who are consumerists who waste energy, food, and materials because they throw away & repurchase constantly for convenience. I know families that are very conscious about the environment, always recycling, not wasting, being careful about energy and food consumption.

    Another important issue is fuel consumption. Some single people travel constantly by airplane, take long road-trips and long commutes, and purchase items from the other side of the planet. These single people may carry a higher carbon footprint than entire families who stay local in their vacations, have short commutes to work/school, and purchase locally.

  60. Peter Oh says:

    Poor guy, studio lighting must have made it unbearably hot. Towards the end, his perspiration soaked the armpits on his baggy, ill fitting button up.
    Excellent presentation identifying problems and solutions of population growth. However, it seems for all of humanities intelligence and ingenuity, we can't get our act together. People are like bacteria growing unchecked on a Petri dish until all the medium has been used up, and the toxins produced by the micro organisms metabolism has made the environment unsuitable to exist in. It is true that if we used our dwindling resources more effectively and were wealthier nations willing to share, instead of widening wealth poverty disparity, we could probably better sustain the current population. However, human greed prevents this from happening. The current "infinite growth paradigm that rules the global financial systems is clashing with finite resources" (P. Joseph, Zeitgeist).

  61. Peter Oh says:

    It's been stated that if everybody were to have the same standard of living as the average American, we'd need four planet Earths to satisfy everyone's demand. We obviously don't, so to lease a new car every three, get a new cell every two, have an LED screen in every room and generally waste everything is lunacy. We're robbing our future generations inheritance.

  62. Peter Oh says:

    The Malthusian trap still holds true today. By 2050, it will still…..

  63. CosasPerronas16 says:

    help me i need importante fcts about that video!!

  64. Yahsararel Ben Yoseph says:

    how the hell you gentiles keep getting these cool slides to use for presentation…mark of the beast or some deal?

  65. José García says:

    kalla cabron mamahuevo. Me como el panorama klk

  66. jessyka power says:

    Nature takes care of itself bozo

  67. Kevin Woods says:

    We don't want the nudist colony to be lost underwater.

  68. Flavio Schneider says:

    Everybody should watch this

  69. Diogenes Ataraxia says:

    pseudo science.  none of these left wing feel good pansies has the balls to look the brutal truths revealed by Darwin in the eye.  look into the death rates and birth rates of mocking birds, for instance.  now there is a species, like most other wild species, who is in tune with nature, who grows stronger and more efficient with every generation.  mankind is a species that has been domesticated by its own institutions.  one thing is certain and one thing only.  The Demon will have his feast.

  70. Lydia says:

    37:16 and on… hunger being invisible economically, what an interesting insight…and about supporting agriculture research for agriculture that actually supports those that are chronically hungry… (just putting this here in case someone wanted the timestamp where he mentions these topics)

  71. Matthew Jackson says:

    Judging from what he's presented , I guess earning a bachelors degree wasn't as worthless as I thought it was. Come to think of it, l I would have never fared as well without a college education. Personally, I think the future generations will have to earn post graduate degrees to remain competitive in the workplace.

  72. Rudraraju VLN Raju says:

    The lecture was very illuminating. I already see and experience the pressure overpopulation is causing on various life and non-life forms. I hope Homo Sapiens are true to their Sapiens title and avert Malthus's dire predictions.

  73. Sam guy says:

    My heart wasn't ready for all that gore 4:28

  74. Sam guy says:

    This was great.

  75. COMING says:

    Biased video. The solving clue is before agriculture.

  76. UnderStructureRepair says:

    a jew teamed up with rockafeller. how odd

  77. Juan Mendoza says:

    I AM NEVER GOING TO TAKE THIS CLASS BUT I HAVE TO SEE THIS VID BECAUSE OF HW

  78. Paolo Rizzo says:

    I regard this video the most inspirational, instructive and interesting video that I have seen so far. Thanks! for your time to share your knowledge. I wanna compliment this channel for this opportunity. Keep up the good stuff !

  79. Edwin León says:

    Where can I study demography in internet? I'm very interested.

  80. pat crnich says:

    the more educateed you are, the less likely you will be disabled??? I DONT AGREE!

  81. pat crnich says:

    QUESTION posed :why is it better to live in the city? all your answers are based on contraception (biased?)
    here is the real question & answers which you outline yourself

    (AS I PERCEIVE THEM)

    WHY IS it BAD TO LIVE IN THE CITY? the illusion of privacy , all crime (rape? hence the greater need for contraception?) is much higher, there is much social turmoil (war/rioting?) so security is a big problem, more exposure to virus /bacteria from other countries (health problems) the fact that "they" have quadrupled the price (or rents) economic problems, the fact there is no parking, transportation problems. this doesnt sound like living in liberation to me.

  82. michael s says:

    This sounds less like an introduction to a scientific discipline than one of those "save the world" political sermons that have been a favorite indulgence of baby boomers since the 1960's.

  83. Ralgondo says:

    This is such bold,faced liberal propaganda trash

  84. Trushar Patel says:

    By the way any immigrant comes to United States gets tested for TB so there is no chance of infecting any American, India will cope up with the problems by itself. Don’t need any help from so called developing world. Like Polio, India will knock out TB sooner or later. FYI – India’s GDP was 23% when British arrived vendor left India‘s GDP was barely over 3% India is considered as developing country because of British but India is doing great now it’s time to fly.

  85. Thunder Kat says:

    Anyone watching this in 2050?

  86. S. Thym says:

    Thank you. Milles Merci !!!

  87. Feynstein 100 says:

    Demography sounds really interesting. I wish there were a Crash Course on it.

  88. Alissa Jeanfreau says:

    Awesome video!

  89. Hebrew Israelite Doctrine Jamaica says:

    You are not an Israelite Mr Joel Cohen. You fake Jew.

  90. Tebz Nkosi says:

    MCHD peeps, who actually watched this?

  91. 2SSSR2 says:

    Wait… If we cannot say for sure how meny people were alive in 1930 becasue our data coudl not cover entire population then how can we claim that in 1600 years there were only up to 500 million people on the entire planet?

    I challenge that claim and think there were a lot more of Humans living in that time period, especially Roman period.

  92. Vegan Jeffrey says:

    By healthy diet I believe he means vegan diet

  93. Rabble Repository says:

    Guys a hack

  94. Theresa Allauigan says:

    Loved and enjoyed every minute of it. Very interesting and informative. Thanks a lot!

  95. Richard Goldfine says:

    Why do people have children they know they cannot afford to even feed adequately?

  96. God says:

    Stop having so many kids. They grow up and cause more and more traffic for me to sit in!

  97. olong richardj says:

    I love the way you channel it, perfect God Bless you, Baba,

  98. Philip Morise says:

    My take away from this is: unless we change our ways, nudist colonies of the future are in grave danger!

  99. Justin Waters says:

    The human population growth curve looks like the Bitcoin bubble.

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