"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. "
Source: after Chapman and Reiss 1995
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).
Improvement in technology, could in each
kind of society lead to some possibilities for expansion, e.g. spears and
digging tools could allow hunter and gatherers to harvest a larger share of the
surplus of their habitat; the introduction of crop rotations and other improved
agriculture method could perhaps double or triple the yields, but it was only
through employment of industrial technology that yields could increase tenfold.
In the same way, improvements in technology has constantly expanded our ability
to feed more and more people on the planet also during this industrial phase,
but limits are now occurring from all sides. It is hard to see what could be a
similar radical change of conditions which would allow us the make another
giant leap in population. The options seem to be expansion to new planets; or the
introduction of a totally managed planet, with abundant energy sources (e.g.
solar or nuclear) and the production of synthetic food on a large scale.
Failing any of those, we have to make the best out of what we know and have.
Part of that is keeping the population on reasonable levels.
Too few is also not always good
While we can agree than the size of the
population is a problem, there are many examples of how high population density
forces a more sustainable use of the landscape than a sparse population. e.g.
In Germany, Japan and Sweden it was first the exhaustion of, or the threat of
exhaustion of, forest resources that compelled people to manage the forests
properly and it was the increasing population that made farmers abandon the
extractive practice of sod cutting to fertilise their soil (Radkau 2008).
Similarly, regardless of how much environmentalists and foresters condemn
swiddening agriculture, it will continue to be the norm until population
density reaches a certain level, simply because it is the most comfortable, and
secure, and also sustainable, way of getting a good return on labour input. It is pointless to try to make
poor farmers switch to other cultivation system before the productivity of the
agro-ecosystems is threatened. Already the Egyptians, who operated a limited, but
fertile land resource knew that it was beneficial to alternate cereals and
fodder crops such as clover or alfa alfa (Mazoyer and Roudart 2006), but it was
only under the pressure of population that crop rotations that integrated
fodder production and grains became wide-spread in Europe. Similarly, it is the
population density of China over a long period that made the Chinese utilise
human excreta in an efficient way, while in sparsely populated Africa it was
not in use. So while a big population in general is problematic, there are
situation where it is not that bad, or at least where we have not managed well
with low population.
Some of the ecosystems we have created are
dependent on humans, and that with continued urbanization, we actually get more
and more areas that are depopulated. Because we have not planned how these
depopulated landscapes shall look like and work, societies end up paying farmer
or entrepreneurs to ”maintain” the landscapes or preserve the ”cultural
heritage”. And it is not only in high income countries this is a problem. Some
areas with traditional rice paddies experience labour shortages to maintain the
infrastructure. In 2007, I visited traditional farms in Bali and their main
problem was that youth preferred to work in the tourism industry over farming.
In that way the truly amazing landscape and culture was no longer sustainable
as people voted with their feet for another life. If the terraces are not
maintained, they will collapse from erosion, with potential devastating landslides
as side effect.
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.
Extract from Garden Earth
Extract from Garden Earth