and fifty years ago life was very insecure in Western Europe. Birth
and death rates were high and life expectancy was low: a quarter of
children might die before their first birthday, and famine or epidemic
frequently decimated populations. Since then, Western Europe and North
America have gone through a demographic transition that has radically
transformed our lives and the world we live in. In this interview Tim
Dyson, professor of population studies at the London School of Economics
and Political Science, discusses the demographic transition throughout
the developed and developing world, and considers the invisible yet
powerful forces of population growth and decline, of mortality and birth
you outline the main population trends in the world today?
Dyson: The countries of the world can be divided into three broad
categories. First, there are those countries where birth rates are still
high--about 35 or 40 births per 1,000. These sorts of populations are
to be found in northern parts of the Indian sub-continent and large
areas of central and west Africa. The populations in such areas are
growing fast. They are young populations with high birth rates: In parts
of sub-Saharan Africa populations are growing at rates of 2.5 or even
3 percent per year. Although birth rates are still high, they are in
general decreasing in this category of country, but it is going to take
several decades before they reach acceptably low levels.
At the other
end of the spectrum are countries with very low levels of fertility.
These include most of Europe, Japan and, to some extent, China. On average,
in these areas women have two or less live births each. Their populations
are fairly old--they are going to age increasingly as the decades go
by--and they are not growing very fast. In fact some of these populations
would be declining were it not for a certain amount of in-migration.
The main contrast
between these two types of population is that the first group have high
fertility and the second group have very low fertility. Virtually the
whole world is moving from the high group to the low group, so most
countries fall somewhere between the two.
There is one
other broad group of countries that I think has to be identified nowadays.
This is the group of countries badly affected by HIV/AIDS. The countries
worst affected are in sub-Saharan Africa, particularly in eastern and
southern parts of sub-Saharan Africa. They have increasing death rates,
and in many of them life expectancy has reduced very substantially.
Many of them also have declining birth rates, and as such are moving
towards a situation of zero population growth. However, this is due
to a very particular event: namely the HIV/AIDS pandemic.
factors influence the decline or increase in population growth rates?
In small countries migration can be a very important factor. The smaller
the population, the easier it is for in-migration or out-migration to
have a significant effect on whether the population is growing or shrinking.
In very large countries, such as China or India, in- or out-migration
has virtually no effect on the rate of population growth, simply because
the populations themselves are so large that even the out-migration
of several million people has a negligible impact on the overall rate
of population growth. However, migration is very variable from country
The main factor
that differentiates populations around the world is the birth rate.
In parts of sub-Saharan Africa and North India, women have on average
five live births. That means that birth rates are very high. Death rates
everywhere have declined quite substantially in the last 40 or 50 years,
so these populations are growing, essentially because of the high birth
rates. A key issue for the future is how fast birth rates come down
in different populations.
in mortality applies in virtually all developing countries as well.
For example, life expectancy in India at independence in 1947 would
have been slightly over 30 years. Today it is more than 60 years. This
means life expectancy has almost doubled in the space of 50 years--a
tremendous improvement. Most countries in sub-Saharan Africa were also
experiencing improving mortality and death rates until the advent of
the HIV/AIDS epidemic, which is a very particular tragedy. If you look
at developed regions of the world, such as Europe, Japan and North America,
life expectancy has continued to climb and is, in general, still going
impact has demographic growth had?
It is probably best to divide this question into two. We can consider
the impact of demographic growth on individual countries and then on
the world as a whole.
In the context
of the world in which we live, there is a general view (at least among
demographers) that rapid population growth is problematic for poor countries.
It means that governments have to provide more schools and more jobs
for constantly expanding populations of children and people of working
age. One of the great advantages of a slower rate of population growth
is that, rather than building more schools for servicing an increasing
number of children, you can commit resources to improving the quality
of education that children get. Eventually, one of the advantages of
slower population growth is that governments don't have to produce quite
so many jobs. Thus for very poor countries rapid population growth poses
major challenges from an economic perspective.
population growth can pose a number of other serious challenges. If
one ethnic group is growing or thought to be growing faster than another
ethnic group, it can lead to political turmoil. Also, in some parts
of the world there is no doubt that rapid population growth has contributed
to environmental deterioration. For example, in parts of sub-Saharan
Africa there has been very little increase in agricultural yields, even
though populations are increasing, so the only way they can produce
more food is to bring areas of forest or savannah into agricultural
of population is urbanisation. Urbanisation tends to proceed as the
demographic transition occurs. The developing world has witnessed the
rise of rapidly expanding cities, which might be growing at rates of
3 or 4 percent per year. These citizens require housing, sanitation,
water supplies, electricity ... the list goes on. The challenges surrounding
the provision of urban infrastructure are absolutely immense.
When I was born
the total population of the world was about 2.5 billion. The world's
population now is over 6 billion, and it will probably increase to something
approaching 9 billion. In my lifetime we have been adding an extra billion
people about every 13-14 years; yet when I was born, there were only
2.5 billion people on the planet. This does have, I suspect, major consequences
at the global level--not so much in and of itself, but combined with
the fact that, as populations develop, they use more and more energy.
In other words, I think that demographic growth at a global level is
problematic if you couple it with the levels of energy that we consume.
I hasten to add that it is the rich populations of the world, such as
Western Europe and North America, that burn a lot of oil, coal and fossil
fuels, and make a large contribution to the phenomenon of global warming.
Increasingly, however, development in the rest of the world means that
populations there, quite reasonably, will follow similar paths, perhaps
with greater efficiency than we did in the past, but nevertheless they
are going to be burning more fossil fuels too. So when considering what
the problem for population growth at the global level is, I think we
must take into account the increased levels of energy use. We may well
be facing severe challenges in the decades ahead, as many people realise.
is the demographic transition? Has it had any broader consequences for
society as a whole?
I do think it's important to define the demographic transition. If we
go back 150 years in Western Europe, birth and death rates were high
(30-40 per 1,000), life was very insecure and women had high levels
of fertility. If you look at much of the developing world, those sort
of conditions applied 50 or 60 years ago. The demographic transition
is the process whereby death rates drop, the population starts to grow
and, after a delay, the birth rates come down as well. Given a hundred
years, you find that birth rates and death rates are both low. So the
demographic transition is the transition from high birth and death rates
to low birth and death rates. Western Europe and North America have
come through the demographic transition. Many countries in the developing
world are still going through it.
of this transition are absolutely huge. One of the things that occurs
as populations go through it is that they start to urbanise. From having
a relatively small urban sector, the demographic transition brings about
the urbanisation of the population. Whereas in Africa today, 20 percent
of the population live in cities, in Western Europe 80 percent of the
population live in cities. Another aspect of the transition pertains
particularly to women's lives. The demographic transition massively
changes the condition of women's lives and therefore underpins the changes
that take place vis-à-vis women's position in society.
In a pre-transition state, women might have had, on average, six live
births during their reproductive lifetime. It monopolised their lives.
High fertility trapped women within the domestic domain. High fertility
also goes with high mortality: although women might have six live births,
they also lose a substantial number of them. In the post-transition
state, women have two live births on average and they live much longer.
Their two children will probably survive, so reproduction and the domestic
domain comes to take up a very much smaller proportion of women's lives.
One of the indirect consequences of the demographic transition has been
that women have had their position transformed.
notice the demographic transition. It occurs over very long periods
of time. In the case of England that transition took 200 years to work
out. China is a supposedly rapid transition state but, even though China
began to go through it in the 1930s or 1940s, its population will still
be growing 20-30 years from now. Birth and death rates came down really
quite fast, yet the effects of the transition will last for a period
of 100 years. Individuals don't really get to witness those sorts of
changes, although they are absolutely fundamental to the way in which
human beings live.
I live in a society where life expectancy is roughly 75 years; that
applies throughout the developed world. It would be salutary if we were
to transport ourselves back to circumstances in which a quarter of children
might die before their first birthday, life expectancy at birth could
be 30 years or less, there were famines and epidemics of various kinds,
and women were having six live births each. That was a totally different
world to the one in which you and I are lucky enough to live. It was
a world in which people could not plan or control their lives. However,
as mortality has improved, so us human beings are very considerably
more secure in our environment, and have been able to invest in such
things as education in a way that would have been almost impossible
when life was unpredictable and hazardous.
The reasons why mortality declined in Europe and North America historically
undoubtedly had a lot to do with environmental improvements, water supplies,
sanitation, housing, clothing, cleanliness and those sorts of fundamental
changes. As time went by, our knowledge about disease causation and
our medical techniques improved, and these have made contributions as
well. The developing world has benefited to a considerable extent from
technical advances devised elsewhere, such as immunisation. In some
developing country contexts, sub-structural socio-economic processes
have played less of a part in reducing mortality than technical inventions
that have come from elsewhere.
affect the demographic transition?
It all comes back to this issue of mortality decline. I don't think
governments had much to do with the mortality decline in nineteenth-century
Europe. However, looking at the developing world today it is clear that,
by introducing various health programmes, governments have had a great
deal to do with the fact that their populations are living longer. To
some extent the same point applies to fertility. Fertility in Western
Europe didn't come down because of government programmes. It came down
for a variety of reasons, but essentially people during the first half
of the twentieth century and the latter part of the nineteenth century
decided for themselves that they wanted to control their fertility.
were very aware of the fact that if their birth rate stayed high then
there was going to be very considerable population growth. Governments,
first in Asia and then elsewhere, decided that they wanted to facilitate
the reduction in birth rates, so they set up family-planning programmes.
Although there is a lot of academic argument about whether family-planning
programmes are effective and how much they bring down birth rates, I
don't think there is much doubt that they played some role in making
birth rates come down faster than they otherwise would have done. Nowadays,
in the so-called `developing world' vis-a-vis both mortality
and fertility decline, governments have been much more proactive than
was the case historically.
feature was taken from an interview held at the London School of Economics
and Political Science on 7 May 2002. Copyright London School of Economics
and Political Science.