This week we will focus on population – the movement of humans through time. Our emphasis will be on population geography which focuses on the number and distribution of humans over specific areas in space, over specific regions, at specific locations. Like all other aspects of geography, population geography looks at how the environment impacts population trends. Today, we will discuss beliefs about population trends and how they have changed over time; we will introduce the concept of the Malthusian Catastrophe and we will examine how population is distributed over the Earth.
The insight that Malthus had in regards to population was that population increases exponentially (2,4,8,16,32,64 etc.) versus resources which can only increase linearly (2,4,6,8,10 etc.). Another way to phrase this: the slope of the population function in relation to time is ever-increasing while the slope of the resource function stays constant. At the point where population exceeds resources, there will be starvation, war, famine, chaos. This is the Malthusian Catastrophe.
In the late 1960’s and early 1970’s, a group of scientists known as the Club of Rome analyzed all available population data and concluded that the NIR was about 2.5, meaning that the population of the earth would double by the year 2000. The Club also analyzed resource availability at the time and concluded that there as no way we could grow enough food to feed our population by the year 2000. The Club of Rome predicted the arrival of the Malthusian Catastrophe within the next thirty years. This idea quickly became the talk of every newspaper and news program on TV. The book pictured here, “The Population Bomb” sold millions of copies. This belief in the inevitability of the Malthusian Catastrophe helped jump-start the environmental movement in many countries.
In 1973, the movie “Soylent Green” pictured the overpopulated, resource-scarce world of 2022. A wealthy minority lives in guarded, gated high rises while the majority live dreary lives packed into slums, with their only food being a bland cracker made from algae known as “soylent”. The film is an excellent window into the minds of people in the early 70’s, convinced that a Malthusian Catastrophe is imminent.
But, of course, the Malthusian Catastrophe did not arrive. Two reasons: first, the NIR used by the Club of Rome was too high. The real result was closer to 2.3, not 2.4. A small difference but one that translates into much slower growth. As more time passed, the NIR continued to level off and decrease. China’s “One Child” policy plus the increasing availability of education and birth control in the developing world were big reasons why the NIR leveled off. On the resource side, a series of scientific advancements including genetically-modified crops and better fertilizers resulted in an explosion of growth in agriculture known as “The Green Revolution”. Finally, free trade and globalization improved overall resource allocation. In short, these improvements shifted the entire resource curve upward.
As our Demographic Transition Model would predict, our most developed countries are low growth and our least developed countries are moderate growth (the advances of industrialization are not prevalent enough to fully reduce the death rate). The explosive growth is found in the developing countries – these are nations that are undergoing industrialization and switching from agriculture to manufacturing. Better economic outcomes are dramatically reducing the death rate while the birth rate stays high, resulting in a high natural increase rate.
This cartogram shows the area of each country as proportional to its population. Notice how negligible large area but relatively low population countries like Russia and Canada appear on a map of this kind. China and India dwarf the United States.
The darker the red, the denser the population – note that population is clustered in about a half dozen different regions. Review – this is a choropleth map in which the population data is overlain on top of a location map using a conformal (note the distorted size of Greenland) as opposed to an equal-area projection.
The four regional concentrations of population are East Asia, South Asia, Southeast Asia and Europe. Together, these four regions account for two-thirds of the world’s population. Note the surprise (to Americans) of Southeast Asia. We typically don’t think of Indonesia or the Philippines as being leaders in world population – but this region accounts for a greater share of the Earth’s people than all of Europe. Note also that North or South America don’t rank in the Top 4.
Only one-twentieth of the Earth’s land surface is currently occupied by humans – this area is called the Ecumene. Humans tend to thrive in temperate climates (and not near the equator). Humans show a strong preference to be near the water – beachfront property is universally prized across cultures. Environmental determinists would argue that the physical conditions of the Ecumene has shaped human behavior and culture whereas a possibilist would say that humans beings have shaped the Ecumene to better suit their preferences.
Deserts occupy a significant fraction of the Earth’s surface (especially the Sahara in North Africa). While humans can adapt and survive desert conditions, it is not pleasant and most pre-Industrial desert societies lived there because they were forced there by other, more powerful groups who had monopolized the Ecumene.
Again, while small groups of humans have occupied areas outside the Ecumene, such behavior is outside the norm. The case of the determinists is strengthened by physical adaptations present in humans outside the Ecumene. The sickle cell trait gives partial immunity to malaria in those living in tropical wetlands. Andes natives exhibit larger than average lung capacities to handle thin mountain air. Natives in polar regions have shorter limbs which aids in keeping core temperatures regulated.
This is the simplest measure of population density – simply divide the number of people by the available area. Think of the cultural differences regarding eye contact and acknowledgement (ex: waving hello) in high density environments (like New York City) versus low density environments (like rural Wyoming).
Physiological density measures carrying capacity – how many people does each segment of arable (farm) land need to feed? The higher the physiological density, the more vulnerable you are to famine. The lower your physiological density, the more likely you are to be a net exporter of food and enjoy an agricultural surplus.
Our final density measures looks at the number of farmers per unit of arable land. It measures agricultural efficiency and industrialization. Low numbers mean better and more efficient farming, high numbers indicate an inefficient farming system.
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