The document discusses theories of human population growth and carrying capacity. It describes Thomas Malthus' theory that population grows exponentially while resources grow arithmetically, leading to natural checks like famine. In contrast, Ester Boserup argued that population increase spurs innovation to boost food production through technologies like irrigation and fertilizers. The document also discusses factors beyond population size, like wealth and resource use, that impact carrying capacity. It concludes that both theories may apply differently depending on whether environmental or cultural limits are considered.

1. Topic 3.7
Limits to Growth

2. Human Population Growth
• Carrying Capacity
– The maximum number of individuals of a species that
can be sustainably supported within a habitat. It occurs
when birth rate is equal to death rate
• But does this really apply to human populations?
• Do human populations actually have a carrying
capacity?
• Well, there are many examples of direct and
indirect effects of drought, famine and war which
act to reduce populations when they grow too
large

3. Human Population Growth
• Size of population isn’t the only factor which
impacts on natural resources
• Other factors include:
– Wealth (MEDC or LEDC)
– Resource desire
– Resource need (or use)
– Age distribution
– Rural or urban populations
– Time (it is dynamic)
80% of the world’s population lives in MEDCs where birth rate is falling (or negative,
e.g.Japan)
20% of the world’s population lives in LEDCs where birth rate is increasing

4. Malthusian Theory
• Malthus believed that human populations
grow exponentially, but resources only
grow arithmetically (limited by land
availability and existing technology)
• Food production can only therefore
increase to a certain level
• Above this level, soil erosion and
decreasing soil fertility cause productivity
to decrease
• A natural check on population occurs
Thomas Malthus

5. Boserup Theory
• An increase in population will simply stimulate
scientists to come up with ideas to increase food
production
• “Necessity is the mother of invention”
• Productivity has been increased by:
– Reclaiming land from the sea
– Selective breeding and cross breeding
– Developing high-yield plants
– Genetic modification
– Terracing
– Hydroponics
– Greenhouses
– Irrigation
– Artificial fertilisers
– Switching to new crops (e.g. soya)
– Fish farming
Ester Boserup

6. Problems
Malthusian Theory Boserup Theory
Malthus assumes a ‘closed system’ of
human population
Bosrup assumes a ‘closed system’ of
human population
The distribution of food resources is not
fair and equitable. Only the poor really
suffer from lack of food
There are examples where human
activities have led to desertification of
huge tracts of land
Malthus could not have predicted the
amazing changes in technology
In LEDCs, food shortages lead to
emigration rather than innovation
Food resource availability has not really
increased ‘arithmetically’
Innovation occurs in MEDCs and is not
always shared with LEDCs
Malthus did not predict the globalisation
of food supply
Perhaps both theories work, but in different ways. Malthus was referring to
environmental limits, while Boserup refers to cultural and technological issues
https://www.youtube.com/watch?v=dN06tLRE4WE

7. Can Carrying Capacity Change?
• If we cut down on our use of natural resources
• It may be achieved by:
– Recycling (reprocessing materials into new
products)
– Re-use (returning materials to the manufacturer
of processor, or finding new uses ourselves)
– Reduction (using less energy or resources)
– Substitution (switching to renewable resources
from non-renewable)
https://www.youtube.com/watch?v=E8dkWQVFAoA

8. Questions
1. Explain why it is difficult to apply the idea of
carrying capacity to a human population
2. List and explain ways in which human
behaviour may increase our carrying capacity
3. Compare and contrast the Malthusian and
Boserup theories of human population
growth