Below is an Extract from Garden Earth, about population:
The population follows our production system
Humans, like any other species that
conquers a new habitat, shows an exponential population growth. What is unique
for us is that we have been able to radically expand our ability to tame nature
and other organisms and direct their production to our stomachs and our bodies.
Instead of following a typical S-curve of growth, we have two times restarted
population growth. The first time was with the introduction of agriculture, the
so called Neolithic or agrarian revolution. Before that, our population grew
mainly through expansion into larger and larger areas and into more and more
ecological niches. Our role was more or less the same, we lived on the
surpluses from other species, which we collected, hunted or fished depending on
niche. Population growth was very low, perhaps just 0.001 percent per year (to
be compared with 1.8 percent 1990). 12,000 years ago, we were probably less
than ten million on the planet, and most likely, the ecological limits for
further growth were reached. With the transition to agriculture, many more
could be fed from a defined area, but not everywhere, as some parts of the
world are not suitable for farming. A period of rapid growth ensued. In ten
thousand years, the population grew 250 times. At the time of the industrial
revolution, the population had reached the new ecological limits in many places
in the world. Not so densely exploited areas were rapidly filling up with
settlers from Europe, representing one third of the annual population growth of
Europe. Through the deployment of huge amounts of fossil fuel, first coal
followed by oil, we got the possibility to, once again, take a giant leap to
new levels (Chapman and Reiss 1995, Livi-Bacci 1992).
Numbers are stabilizing
Forty-three countries, including Japan,
Russia, Germany and Italy have populations that are stagnant or even
decreasing. A larger group of countries, including China and the USA, has
reached the stage where new families will be smaller. When next generation
reaches fertile age, population will stabilize. The third group will have
doubled its population from now to 2050. This group includes many of the
African countries, such as Ethiopia, Congo and Uganda. The predictions of the
UN have three alternatives for 2050, 10.8 billion, 9.2 billion or just below 8
billion. Most seem to bet on the middle alternative. That Malthus’ horror scenario
of mass starvation has kept its appeal over two hundred years coincides with
the start of the demographic transition of England following an unprecedented
population explosion. And that pattern has been repeated in country after
country, so in the same way as Ireland was the frightening example
hundred-fifty years ago, Nigeria or Ethiopia are now. Studies of the
demographic transition in the high income countries show a strikingly similar
pattern in most countries. First death rates decline rapidly - and it is not
primarily the old that live longer but more children that survive. This leads
to very big cohorts of youth, reaching 35 percent to 40 percent of the
population. When birth rates go down after a while, a big wave of people will
reach the stages of young adults, mature adults and old people.
Why is population stabilizing?
It is perhaps a strange question, but it is
much more remarkable that the demographic transition has taken place and that
populations are not growing, than
that there has been a population explosion. After all, we have been taught that
the strongest driver of them all is to reproduce, to spread our genes. And why
are populations stabilizing now and not hundred years earlier or hundred years
later? Why is it not stabilizing in the countries where population is still
growing? Is the reason technical, such as contraceptives; economic, such as
increased wealth; human, such as improved education of women or is it social,
perhaps a result of shift in values? It is interesting to understand what
drivers which make individuals change their reproduction. There are actually
very few reasons for why a European woman (or her possible partner) today only
wants two children, while she wanted four some hundred years ago. It appears to
completely contradict the socio-biological ideas that humans only act with the
purpose to spread her genes. If that were the case, voluntary birth control
would never occur. It is more a process of culture and values. For a long
period, it was well known that smoking causes cancer and other diseases. Still
it was a long and slow process until this insight led to a changed view on
smoking and subsequent regulations. It is interesting that the view on smoking
is now changing in all countries, also in countries where smoking is perhaps
not a primary health problem (because people don’t live long enough to die from
cancer). In the same way it appears that the regulation of populations have
little to do with if the country is overpopulated or not. Sweden and the
Netherlands stabilized their population more or less at the same time despite
that the actual population density is very different, large tracts of Sweden
are rather "underpopulated" if there is such a thing. So called soft
factors, values and education, seem to play a big role here. At the same time,
on a global level, it is hardly a coincidence that populations level off at the
same time that we see more and more limits to growth.