So, now that we know what Demography can do for us. Let's get into the first important question here, which is, "What's the projected growth of the world's population?", but more importantly, "How is that going to be distributed by different regions or parts of the world?". So first of all, let me define for you two basic concepts that we are going to be using throughout this class. The first is Total Fertility. So total fertility is how many children are born per woman. To be more precise, it's the average number of children that hypothetical cohort of women will have at the end of their reproductive period if they were subject during their whole lives to the fertility rates of a given period, and if they were not subject to mortality. So in other words, what we're doing when we're calculating Total Fertility, is how many children are born to the average woman in the world over her lifetime. That's the first concept that we're going to be using here. And the second concept is Life Expectancy at Birth. And this is typically measured in years. So Life Expectancy at Birth is the average number of years of life expected by a hypothetical cohort of individuals who would be subject, during their entire lives, to the mortality rates of a given period. So for instance, I was born in the 1960s. What you should do is then take a look at what would be the average person in terms of Life Expectancy at Birth, assuming that that person was born in the 1960s. And in a moment I'm going to show you the examples of different parts of the world and different numbers for both Total Fertility and Life Expectancy at Birth. As I told you earlier, we're going to be using the data compiled every year by the United Nations Population Division. And remember, that the division gives us four different forecasts into the future: no change or constant, high, medium, and low. From now on, I'm always going to give you forecasts into the future based on the medium assumption. Remember that this is the assumption that the United Nations believe has the highest probability of being true. And for life expectancy which is the opposite of mortality, of course, we're going to be using the only variant, the only assumption that the United Nations publishes in its projections for population around the world. Now I would also like to define for you different regions of parts of the world because I would like to give you the information broken down for each of these regions. In particular, I am going to classify each country in the world into the three different groups. The first group of countries includes the more developed nations in the world. That's Europe, the United States, Canada, Australia, New Zealand, and Japan. The second group, it's called the less developed parts of the world. It includes parts of Africa, most countries in Asia (excluding Japan), most countries in Latin America and the Caribbean, and most countries in Oceania (excluding New Zealand). And then we have the least developed countries in the world. These are 49 very poor countries of which 34 are in Africa, nine in Asia, five in Oceania (which is the Pacific region), and one in Latin America (which is Haiti). Let's take a look at this one chart here, that gives us a very, very important information about how fertility is changing in the world. Once again, remember that fertility is the number of children that are born to the average woman in the world over her lifetime. Once again, we're using here the medium projection or forecast, as published by the United Nations. The chart starts in the year 1950 and until the year 2015, we have actual record of the data. We know what has happened. And then beyond the year 2015 until the end of the 21st century, we have the medium projection. Vertically, once again, we're measuring Fertility, number of children per woman. As we can see for the entire world which is the thickest line, back in the year 1950, the number was about five children per woman. That number has been coming down quite quickly to a level of about 2.5 by the year 2015. And the projection, is that over the next few decades that number will continue to drop, approaching the number of two children per woman. That's for the entire world. Now let's take a look at the more developed parts of the world -- the US, Europe, Canada, Australia, New Zealand, Japan. That is the line that starts at a level of just below three and drops until the year more or less 2000, and then starts to grow very slowly. Notice that the line actually at about the year 1970 drops below 2, which means that in the more developed parts of the world the population has not been replacing itself. If it weren't for Migration, the number of people living in Europe or the United States today, would be lower than 20 or 30 or 50 years ago. Also notice, that the fertility number for the more developed parts of the world has been growing very slowly since the year 2000. And I would like to ask you -- How exactly, why do you think this is going on? Well the reasons are that, number one, governments in Europe and in the United States are offering incentives for families to have more children. They're offering them tax breaks or they're offering them better day care facilities. But more importantly, the second factor that accounts for these slightly increasing fertility (both in Europe and the United States) since the year 2000, is that there's more immigrants, and immigrant families, historically, tend to have more children. Now we can also take a look at the less developed parts of the world, that's the thin line that starts at a level of about six children per woman in the year 1950 and then starts to drop very quickly, especially since the year 1970. Remember that the countries included here are places like China, India, Brazil, Indonesia, Mexico, Malaysia, Egypt, and so on and so forth. And then lastly, we have the poor countries in the world, which is the dotted line that starts at a level of about 6.5 children per woman, continues to increase a little bit approaching seven until the year 1975 and then it starts to drop. Now notice then, that fertility has been coming down in all parts of the world, with the only exception of the rich countries, where it came down until the year 2000 and then it reversed direction but only at a very, very slow growth rate. So my question to you is -- Why do you think that we're having fewer babies in the world? Why do we see that fertility is coming down? What accounts for that? Think about it. Demographers will tell you that by far the most important reason why fertility is coming down is because of the changing role of women in society and in the labor market. You see 100 years ago, there were very few women (anywhere in the world) who worked outside of the household. If anything, they would work on the land but they will still have many babies because farming families needed a lot of labor for the farm. But things has started to change, first in Europe and the United States, at around the year 1910 or so. Women started to have better access to education and also better access to labor market opportunities. Many of them started to complete high school and a few to attend college. By the year 1950, 1960, 1970, increasing numbers of women were attending college. And then many of them also pursued graduate school. So the mechanism is the following: as women have better access to education, they postpone having their first child instead of having their first child let's say at age 15 or 16, they have their first child at age, on average right now in the United States, 26 or 27. So, therefore they end up having fewer children. Let me share with you the example of my own family. I told you at the beginning that I was born in Spain and these are two of my great, great, great grandparents. My great great grandmother, who is on the left of the picture, she gave birth to 21 babies. That was more than 100 years ago. And believe me, many families, many women at that time had 10, 15, even 20 babies. Remember that not all of them survived. In fact, in her case, three or four of her young children, we actually don't know exactly how many didn't survive their first year of life. Now, my grandparents, my great, great grandparents had a farm. They did labor for the farm. And of course, they didn't have access to contraception. All of these things have an impact. The role of women in society has a very large effect on demographic trends, in particular, fertility. But there's, of course, many other factors that produce the effect that you've seen on this chart. It's also that children have become so much more expensive than in the past. We think about children as an asset. We invest in them. We want to send them to the best schools. We want to send them to the best summer camps. We want to offer them the best educational opportunities. So, therefore a lot of couples these days are thinking -- "Well, I don't want to have three kids because maybe I won't have enough money or I won't be able to allocate enough attention to all of them, so I'd much rather have only two. Or, I don't want to have two kids, I'd much rather have only one." So the cost of raising kids, especially in the rich countries but also increasingly in emerging markets around the world, is also something that is decreasing fertility. Now also think about the fact that children used to be a form of insurance. In other words, before we had governments providing pensions, or before we had mutual funds or pension funds, people used to rely on their children so that they could be safe and have enough money for their old age. But today, that's increasingly not necessary. People don't need to have more children so that they have enough resources, or they have somebody to take care of them once they retire or they grow old. So all of these factors are essentially pushing fertility in most parts of the world. Remember again not in the rich countries, towards lower levels. Now we shouldn't forget, of course, that in a very important country in the world because of its size, China, the government also legislated that people living in most areas couldn't have more than one child. That was the famous one child policy that is started in 1970s. I should tell you that fertility in China actually started to come down in the 1950s. Well, before the government introduced a one child policy and at the present time even after 25 years of the one child policy in China, the fertility rate is about 1.7 children per woman. Now as you know the Chinese government, a couple of years ago, started to relax the one child policy. So we might expect that fertility in China is not going to fall as quickly as it has been falling in the recent past. But I do not believe, neither does the UN believe, that fertility in China is going to increase in a dramatic way. Now, I'd like to also share with you an important fact here that is important to keep in mind for analysis of demography, which is that I told you earlier, that when the fertility rate falls below two then the population doesn't replace itself. In fact, the technical number is more accurately said at 2.1, not two. Think about why it may be the case that we need at least 2.1 children per woman in order to ensure that the population replaces itself over time, and not two. The reason, of course, if you think about it, is that not all women decide to have children. There's always a small percentage of women, in every country in the world, that decide not to have children. And there's always a small percentage of women, who for whatever reason cannot have children. Besides that, there's also women who are born and unfortunately they die before they have a child. So it is for this reason that the United Nations and demographers, in general, calculate that in order for a population to replace itself, you need approximately 2.1 children per woman. So, so far, we have discussed and analyzed the first or the most important part of the equation here in terms of demographic changes, which is how many babies are born. But we also need to take into account, how long people live on average and if you remember, we can capture that through the concept of Life Expectancy at Birth. So on this chart, I show you actual and forecasted figures for Life Expectancy at Birth for different parts of the world. And remember, the vertical dimension is years. We're calculating here how many years, on average, a person born in a given year lives. Horizontally, we have the same time period as before, the chart starts in the year 1950 and it goes all the way to the year 2015, with an actual recorded data. We know what has happened. And then from the year 2015 on wards, we have medium projections. Always remember the medium projection. So the thickest line, that starts at a level of about 48 years, is for the world as a whole. And as you can see, it grows over time and it is projected into the future to grow. Meaning, people are living longer and longer and longer. In fact, I could tell you that if you were born in the last 10 or 20 years, you are projected to live, on average, perhaps about seven or eight years longer than your parents, and up to 12 or 14 years longer than your grandparents. That's on average. I cannot make any promises to any one of you in particular. Remember, all of these statistics are based on the average for the entire world over different parts of the world. Now, that's the thick line on the chart. The line that is slightly thinner at the top, which it starts at about 65 years. That's for the richest countries in the world -- Europe, United States, and so on. And as you can see it also increases over time. And at the bottom we have the dotted line, that's for the poorest, the least developed parts of the world. And you can see that it starts at a level of about 36 years but it grows over time as well. And slightly above it, is the thin line that starts at about 41 years old, that's for the less developed parts of the world, including places such as India, China, Brazil, Indonesia, Egypt, and so on and so forth. What I'm sure you can appreciate on this chart is that the growth in average life expectancy is a global phenomenon. In other words, every country in the world is now going through this process of change, whereby people are living longer and longer and longer. So this is good news. But there's another very important thing that I want you to realize about this chart, which is that the poorest countries are catching up. So you see back in 1950, the difference in average life expectancy between a rich country and a very poor country in the world was very large. On the chart, you can see that the difference is about 30 years, right? When you compare 36 years of life expectancy at the bottom of the chart with the least developed countries with 64 or 65 average life expectancy for the richest countries. That's a difference of nearly 30 years. But today, let's say in the year 2016 or 2017, the difference has shrunk to about half. So in other words, on average, somebody in a rich country in the world lives about 15 years longer than somebody in a very poor country in the world. And this trend towards convergence is likely to continue into the future, at least according to the United Nations. Now as you can imagine, the fact that people in poor countries are catching up with those in the rich countries, in terms of life expectancy, is going to have very large implications for the size of different human populations around the world.