Demographics: A Timeline and History
Hazel M Morrow
South University Online

Demographics: A Timeline and History
The human population was estimated to 7 billion in 2013. All these humans did not just appear overnight. The population has increased over the past tens to hundreds of thousands of years. Within recent years the growth rate of the human population has accelerated, causing explosions in population size and density all over the world. This has been due to many different factors. Advances in many different areas of science and technology have helped to increase the lifespan and survivability of humans. The area of social science that focuses on population is called demography. Demography is defined as “the study of the characteristics of human populations, such as size, growth, density, distribution, and vital statistics” (demography, n.d.).
Demographers divide the growth of the human population into 3 eras. There is the pre-agricultural era, the agricultural era and the industrial era. The pre-agricultural period involves anything before about 10,000 years ago, when humans were still in hunter-gatherer societies. The agricultural period which is from 10,000 to approximately 1000 years ago is characterized by humans settling down because of the creation of tools that could help them produce food. The Industrial period is the explosive period of conquest, travel, and technological advancement that started 1000 year ago through current times. Various factors in each period affected how and where the human population grew.
During the pre-agricultural period, the human population is believed to have peaked at about 5-10 million. During this period, humans were primarily hunter-gatherers. This meant food was seasonal and winter was a difficult time. The human population in a given area was only as plentiful as the food they could catch or gather. Also, infant mortality was higher due to environmental factors such as climate and predation. This coupled with shorter adult lifespans, which meant shorter fertility periods, meant that the human population could not grow much faster than it did without some advancement. Also, humans were migratory, so human packs had to keep their numbers down to make sure all individuals were fed.
With start of agrarian culture, humans were able to settle into one place for a long period of time. This meant they could clear the area of predators and create defensible areas and they could cultivate the food they needed. While still heavily seasonal, this cultivation of the food sources meant that human populations could grow. The agricultural period saw the human population grow to approximately 500 million. Technologically, the creation of the plow allowed humans to cultivate greater areas of land into useful food sources. Culturally, humans were able to begin to create things, such as buildings and works of art that held meaning for them. Since humans remained more or less within a single area, they could leave a legacy to those who came after them. Because they stayed in one area, they began to understand how the land, the weather and the environment interacted. This meant they could figure out better ways, using tools, to farm larger areas of land. Since infant and child mortality rates were still high, those who lived within these agrarian communities had many children because farming required a lot of people. Nutritionally, the populace became more reliant on farming, thereby creating a deficit in their diet regarding some nutrients. This factor has been attributed to why the humans actually shrank in stature though the population increased.
Around 1000 A.D., due to shifts in the air circulation above the Atlantic Ocean and the fact that warmer sea currents shifted to flow towards the Arctic, Europe experienced a warmer climate. This warmer climate created ideal growing conditions and a great deal of woodlands were cleared to make way for agricultural. This climate shift freed people from the burden of struggle against the elements to produce food and allowed culture to grow. With the flourishing of culture including the arts and sciences came those who see things differently. These people began to invent things to make life easier or to fill a niche where they saw it. Many advances in basic forms of technology took place during the High Medieval time period and beyond. Advancements were made in sanitation following the Black Plague in the mid-1300s. Because of the cultural exchanges among countries and the advancements in thinking, for every setback that was presented, humans began to try to come up with better ways to overcome them. Medically, humans had begun to study more about themselves and had steadily gained a greater understanding of the many complexities of the human body and brain. Between the years 1300-1400 A.D. there was a cooling trend that occurred in Europe. Despite that and the Great Famine, the human population was the highest it had ever been when the Black Death came. This threw the population into a major decline that they did not recover from for almost 100 years. “Notwithstanding these ecological calamities, the population of northern Europe was at an all time high by the second quarter of the 14th century. However, the arrival of the Black Death, in Europe in 1347 pushed the European population into a century-long demographic decline and caused long term changes in economy and society” (Oosthoek, 2009).
Carrying capacity as applies to population growth is defined as “the maximum population size that a particular environment can sustain” (Simon, Reece, and Dickey, 2012, p. 409). There are 6 different methods used to determine carrying capacity in regards to human population. The first is a straight forward calculation based on regional supportable population density and the area of land available. The problem with this model is that it does not take into account variables of the land, environment, climate, culture… many hundreds of factors that can affect population growth. The second is to extrapolate how the population will fluctuate based on mathematical modelling of the population fluctuates of the past. This method is inaccurate mainly because the reasons for many population fluctuation of the past are poorly understood. Also there was little scientific calculation or project involved in the selection of where the “fitted curves” of the graph of population fluctuation fall. In the third method of calculation, a single constraining factor, such as food or clean water supply versus the human need for that factor is used to figure carrying capacity. While this presents an objective formula, the potential differences in values obtained even from a single constraining resource are large. Another way of trying to calculate carrying capacity is to take several resources and simplify them to a single factor. Many resources that would act as indirect constraints of these factors, so the people who used this model assumed the original resources as the most restrictive of them all. The fifth method is to assume that human population carrying capacity will be “constrained by whatever resource is in the shortest supply” (Cohen, 2002). This method ends up not taking into account all of the other uses for the resource that is being examined. These five methods have the limitation of creating static and deterministic data. They have no way of integrating fluctuations of resources or resource capacity. The sixth method is system modelling. The people put in multiple interdependent factors, and treat them as such, and then run system models of what will happen in various situations. This is by far the most accurate representation because it can take into account many factors at once as well as changes that occur.
Like an invasive species, humans continue grow and thwart the native creatures of an area. We have no natural predators. We are controlled only by our capacity to understand what we are doing to our own environment and how our own spread may be the death of us. However, we are also limited by the carrying capacity of our world. Assuming we do not manage to expand beyond this world, we can only increase our population to the point where we have invaded and destroyed all things that are not necessary for a sustainable environment. Unbridled growth of humans will mean that we have pushed out and made extinct many species due to resource competition and consumption. Unbridled growth of humans could mean that we do irreparable damage to the Earth. This damage could ultimately create a lack of sustainability that ends up culling back the human populations. We continue to degrade the environment by stripping forests to create more land for cultivation, by consuming natural gas and fossil fuels at ever increasing rates that push more and more compounds into our atmosphere that change the way our world works far too rapidly for natural adaption to take place.
Even when looking to restore the environment, we need to keep in mind human population. While we may have the best intentions in reclaiming a forested area, we have encroached on the territories of many other species. Sometimes in our efforts to restore the environment, we disrupt the environment for other species. Human population has tried to conserve/preserve the natural habitats of the creatures they are encroaching on, however it sometimes means that humans do not have enough room to expand either. This will end up causing humans to reach the carrying capacity sooner. Humans however, will not have a sustainable environment if they destroy all of the habitat that the plants and animals need to survive. We should be looking at creating a legacy for our children that involves leaving the Earth in better condition than we got it, however, we seem to be instead accelerating the destruction. Perhaps, before we reach carrying capacity, we will find a way to help both ourselves and our environment. Human innovation got us into the current problem, perhaps human innovation will give us the solution as well.

References

Cohen, J. (2002, November 21). Population Growth and Earth's Human Carrying Capacity. Retrieved from http://www.econ.yale.edu/~nordhaus/homepage/documents/CohenScience_carrying_cap.pdf demography. (n.d.) American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved from http://www.thefreedictionary.com/demography
Leach, H. (2003). Human Domestication Reconsidered. Current Anthropology, 44(3), 349-368. Retrieved from http://www.jstor.org.southuniversity.libproxy.edmc.edu/stable/10.1086/368119
Oosthoek, J. (2009). Beginning of Little Ice Age. Retrieved from http://www.eh-resources.org/timeline/timeline_me.html#mwp
Simon, E. J., Reece, J. B., and Dickey, J. L. (2012). Campbell Essential Biology with Physiology, 4th Edition. Pearson Learning Solutions. VitalBook file.