Easter Island, also known as Rapa Nui, is a small island of 63 square miles that is 2000 miles off the coast of Chile in the southeastern Pacific ocean. The nearest inhabited islands are 1300 and 1600 miles away. So Easter island provides a natural experiment in history. Polynesian people most likely settled on Easter Island sometime between 700 and 1100, and created a thriving culture as can be seen by the island's many huge stone moai and other artifacts. The Easter Island population at it’s peak in 1600 AD was approximately 15,000. By the time the first Europeans arrived by ship in 1722, the island’s population had dropped to approximately 2500. What had happened over 100 years that dramatically reduced the island’s population?

Archeological record shows that at the time of the initial settlement the island was home to many species of trees, including at least three species which grew up to 15 metres (49 ft) or more, as well as at least six species of native land birds. A major factor that contributed to the extinction of multiple plant species (including the trees) was the introduction of the Polynesian rat.  Studies by paleobotanists have shown rats can dramatically affect the reproduction of vegetation in an ecosystem. In the case of Rapa Nui, recovered plant shell seeds showed markings of being gnawed on by rats. Barbara A. West wrote, "Sometime before the arrival of Europeans on Easter Island, the Rapanui experienced a tremendous upheaval in their social system brought about by a change in their island's ecology... By the time of European arrival in 1722, the island's population had dropped to 2,000–3,000 from a high of approximately 15,000 just a century earlier."

By the time of European arrival in 1722, 21 species of trees and all species of land birds became extinct through some combination of overharvesting/overhunting and rat predation. The island was largely deforested, and it did not have any trees more than 10 feet tall. Loss of large trees meant that inhabitants were no longer able to build seaworthy vessels, significantly diminishing their fishing abilities. Another theory regarding the deforestation that caused such ecological and social damage was that the trees were used as rollers to move the 100s of moai statues to their place of erection from the quarry at Rano Raraku. Deforestation also affected agricultural production on Rapa Nui. At first, the native tropical forests provided ideal shade cover for soil. But with much of the native forest being destroyed, with no shade the topsoil eroded causing a sharp decline in agricultural production. This was further exacerbated by the loss of land birds and the collapse in seabird populations as a potential source of food.

Overpopulation with extreme deforestation that lead to the inability to build boats for fishing, the degradation of the soil for farming, the extinction of land birds and the collapse of seabird populations from overhunting along with the impact of Polynesian rats, are thought to have been the main causes for the significant decline in the island population. The inhabitants unknowingly over generations depleted and degraded their limited resources on the island which lead to a significant decrease in population.

Since a picture is worth a thousand words, here's a picture of what Easter Island probably looked like prior to polynesian settlement in 1000 AD, and what Easter Island looks like now post polynesian settlement:

As a simple example, let’s ask a question; does the color of light influence the growth of dandelions? Background research: different color light does affect the growth of plants, but what about dandelions? Much research has been done on different color light affecting plant growth, but not on dandelions! The hypothesis then could be that one of these colored lights will make the dandelion grow the fastest. This method of inquiry is the deductive method, where one can control for variables in the experiment and draw/deduce a conclusion.


Independent Variable
This is the part of your experiment that you will test (vary) to answer your hypothesis. In the example above, the independent variable would be the different colors of the light bulbs.

Dependent Variable
This is what occurs in response to the changing independent variable. In our example the Dependent Variable is how much the dandelion seeds grow.

The control should be the part of the experiment where you do not include the Independent Variable. In our example, dandelion seed that is growing under the white (uncolored) bulb would be your control. The control lets you compare your results in the experiment.


All other aspects (variables) of the experiment remain constant or the same – ie. temperature, type of soil used, amount of water and amount and intensity of the light would all be the same for each group.

So in this experiment you could plant groups of 10 seeds from one dandelion plant in 7 different pots with the same soil in the same room at the same temperature with colored light of the same intensity, but with a red, orange, yellow, green, blue, purple light shining on the pots with planted seeds with a white light on a pot as the control. This is how you would run the experiment. You would then analyze the results and draw conclusions regarding your hypothesis – did any color light(s) make the seeds grow fastest, or did all seeds grow at the same rate? You could then publish these results to share with other scientists.

As mentioned above, this scientific method of thinking or scientific inquiry came about in the 17th century, started by many but most known by Francis Bacon of England. His basic premise was that one should formulate a theory from which logical predictions could be made, which he presented in his book, Novum Organum, or New Instrument, in 1620:

There can and be only two ways of searching into and discovering truth. The one flies from the senses and particulars to the most general axioms, and from these principles, the truth of which it takes for settled and immovable, proceeds to judgment and to discovery of the middle (or lower) axioms. The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general (or higher) axioms last of all. This is the true way, but as yet untried.

The first part of Bacon’s statement refers to deductive reasoning as described in the scientific method and dandelion experiment above, you start with a hypothesis, apply it in a specific, controlled and limited environment, run the experiment, and then draw conclusions. Let’s say we deduced that blue light was the most effective for dandelion growth (experiments with plants have shown blue light to be the most productive).  Deduction is a top down approach, from general to specific conclusion, or big picture to little picture: we started with the question, which of the 6 colored lights were most effective (general/big picture), we ran the experiment and found that blue was the best (specific/little picture).

The second part of Bacon’s statement, “The other derives axioms from the senses and particulars, rising by a gradual and unbroken ascent, so that it arrives at the most general axioms last of all” refers to the science of inductive reasoning. Inductive reasoning starts with many small pieces of information from which, when analyzed, a broad conclusion can be drawn – this is the bottom up approach, specific to general conclusion, or little picture to big picture.  For instance, when in 1543 Copernicus published his theory that the sun was the middle of the universe (our solar system) and not the earth, he had done many mathematical calculations to infer that this was the case. In 1905 and 1915 with all his mathematical calculations, Albert Einstein did the same when he published his theories of special and general relativity. Each of these men drew general conclusions and theories (the big picture) inferred from their specific mathematical calculations (the little picture) that have not been disproven to this day.  These inferences and conclusions are in the physical sciences.

Such inferences and conclusions have also occurred in the biological sciences. Over the course of 28 years Charles Darwin painstakingly documented plant and animal life around the world and particularly the Galapagos islands, and from this data  (the small pictures) in 1859 Darwin published his theory of evolution (the big picture) in his book, On the Origin of Species. This theory has been supported through the discovery of the DNA helix by Watson and Crick. In April 1953, they published the news of their discovery, a molecular structure of DNA based on all its known features - the double helix. Their model served to explain how DNA replicates and how hereditary information is coded on it. This set the stage for the rapid advances in molecular biology that continue to this day.

Such inferences and conclusions have also occurred in the social sciences in studies called natural experiments in history, where various circumstances led to particular outcomes in different historical situations. Such inferences and can very well be applied today to influence the future of society tomorrow.





Science is the study of the real world based on fact and truth. This approach to understanding the world was initially developed in the 16th century, and this period is often called the Scientific Revolution, or the Age of Enlightenment, which Yuval Noah Harari describes rather bluntly in his book, Sapiens, a Brief History of Mankind: "Humankind admits its ignorance and begins to acquire unprecedented power."  The scientific method is a procedure consisting of systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses. A hypothesis is an idea that explains something. The following are the steps in the scientific method:

1: Ask a question

2: Do background research on that question

3: Get an idea, form a hypothesis

4: Run an experiment to test the hypothesis

5: Analyze the results

6: Draw conclusions

7: Share results with the scientific community

So the inhabitants unknowingly over generations depleted and degraded their limited resources on the island which lead to a huge decrease in population. Recall sometime before the arrival of Europeans on Easter Island, the Rapanui experienced a tremendous upheaval in their social system brought about by a change in their island's ecology... By the time of European arrival in 1722, the island's population had dropped to 2500 from a high of approximately 15,000 just a century earlier. What was the social and political environment in Easter Island like over those 100 years, that’s 15,000 people down to 2500 on a small island, that’s an 83% decrease, in just 4 generations. That musn’t have been very pleasant. Losing 12,500 out of 15,000 inhabitants caused by tremendous upheaval sounds rather catastrophic.

Easter Island pre-polynesian settlement 1000 AD

Easter Island post-polynesian settlement now

Chapter 9


Jared Diamond in Chapter 4 of his book titled Natural Experiments of History compares the history and outcome of the island of Hispaniola that was was first discovered by Columbus in 1492. Hispaniola now consists of an island with a border shown above, with Haiti on the western side, and the Dominican Republic on the eastern side.  In 2016 Haiti had a gross domestic product per capita of $739 – that’s the total of gross domestic production per year divided by the number of inhabitants, $739 per person. The Dominican Republic in 2016 had a gross domestic product per capita of $6722 - total of gross domestic production per year divided by number of inhabitants - $6722 per person.  The GDP per person of the Dominican Republic is 9 times that of Haiti, but the countries occupy opposite sides of the same island, so why is there such a difference in GDP per capita?  The answer lies in looking at Hispaniola’s natural experiment in history.  The eastern side of Hispaniola (Dominican Republic) now is green and forested while the western side (Haiti) is brown and treeless. The Dominican Republic receives most of the rain from the storms coming in from the east, leaving less to make it over the mountain to Haiti. Issues in addition to this geological factor significantly contributed to the present difference in GDP per capita. Let’s look at the political history of these countries.  The eastern part of Hispaniola in 1496 was colonized by the Spanish establishing the capital in Santa Domingo. The western side was settled by the French participating in the slave trade.  Two centuries later in 1697 Spain granted France the Western side of the island and a permanent boarder was established in 1777. The economy on the Western side of Hispaniola under French rule was still primarily based on the slave trade, with 85 percent of the population being slaves.  The Eastern side under Spain had 10-15 percent of the population as slaves. There were 500,000 slaves in Western Hispaniola and 15,000 to 30,000 in the Eastern side. The slave economy on the western side lead to a dense population while the French in power cut down trees and shipped the timber back to France. This lead to the deforestation of the western side which resulted in erosion, decreased soil fertility and the general degradation of the land.  Such degradation did not take place on the eastern side. The Haitian slaves also developed their own Creole language which would further isolate them from their neighbors.

Regarding Haitans and Domincans during this time period, Michael Shermer stated things rather well in The Believing Brain: Haitians and Dominicans gained their independence in the early 19th century.  Haiti’s slave revolts during this time were violent, and France’s response to try and keep order caused the Haitian’s to deeply dislike and distrust the French and the Europeans in general. The Haitians wanted nothing to do with the French and Europeans regarding future trade and investments, imports and exports, immigration or emigration, and so they did not benefit economically from these factors. By contrast, Dominican independence was relatively non-violent, and it shuttled back and forth for decades between independence and control by Spain, which in 1865 decided that it did not want the territory. Throughout this period the Dominican spoke Spanish, develop exports, traded with European countries, attracted European investors and immigrants from all over Europe who helped build a vibrant economy.

One can see that from 1496 through the 1800s the social and economic conditions of the inhabitants on different sides of the same island were the primary cause of the different social outcomes of those inhabitants to this day – now those in Haiti have a GDP per person of $739 and those in the Dominican Republic one of $6722.

Another example of the results of a natural experiment in history is the comparison of North and South Korea, day and night satellite pictures above. Korea was ruled by Japan from 1910 until the closing days of World War II. At the end of World War II, the Soviet Union and the United States liberated Korea from imperial Japanese control on 15 August 1945. Korea was then divided at the 38th parallel into two zones of occupation, the Soviets administered the northern half and the Americans administered the southern half. With the border set at the 38th parallel in 1948, two sovereign states were established as a result of geopolitical tensions of the Cold War (between the Soviet Union and the United States). A communist state was established in the north under the communist leadership of Kim Il-sung and a capitalist state in the south under the anti-communist leadership of Syngman Rhee. Both governments of the two new Korean states claimed to be the sole legitimate government of all of Korea, and neither accepted the border as permanent. 

This conflict escalated into open warfare when North Korean forces—supported by the Soviet Union and China—moved into the south on June 25, 1950. On June 27, the United Nations Security Council authorized the formation and dispatch of UN forces to South Korea to repel what was recognized as a North Korean invasion.  Twenty-one countries of the United Nations eventually contributed to the UN force, with the United States providing 88% of the UN's military personnel.

After the first two months of war, South Korean and U.S. forces rapidly sent to South Korea were on the point of defeat, forced back to a small area in the south known as the Pusan Perimeter. In September 1950, an amphibious UN counter-offensive was launched at Incheon, and cut off many North Korean troops. Those who escaped envelopment and capture were forced back north. UN forces rapidly moved North and approached the Yalu river - the border with China—but in October 1950, mass Chinese forces crossed the Yalu and entered the war. The surprise Chinese intervention triggered a retreat of UN forces which continued until mid 1951.

After these reversals of fortune, in which saw Seoul change hands four times, the last two years of fighting became a war of attrition, with the front line close to the 38th parallel. The fighting ended on 27 July 1953, when an armstice was signed. The agreement created the Korean Demilitarized Zone to separate North and South Korea, and allowed the return of prisoners. However, no peace treaty has been signed, and the two Koreas are technically still at war.

Since the formation of North and South Korea, dictatorship and poverty prevail in North Korea and democracy and a vibrant economy prevail in South Korea. As of 2014 the GDP per person in north Korea was $583, in South Korea in 2016 the GDP per person was $27,538. That is a whopping 47 times difference in standard of living! What caused these differences on the Korean peninsula?  Difference in the social, economic and political aspects of society were determined by the inhabitants of each area, with the largest influence being that of foreign powers like the USA on South Korea, and China and Russia on North Korea, after the Korean War.


As can be seen in these three examples of natural experiments of history, social, environmental, economic and political aspects of a society can have a tremendous effect on the future of that society. As citizens in a Democratic Republic deciding the future of the USA, we should keep these natural experiments in mind when voting for our representatives in office to make sure they are leading the country in the right direction. If we are not knowledgeable citizens ourselves when exercising our right to vote in our Democratic Republic, we may not make the best decisions for our country, and we risk losing our role as the most powerful country in the world and, theoretically, in long historical terms, we and the world risk going in the direction of Easter Island, Haiti, or North Korea.



The Believing Brain: Michael Shermer, 2011, St. Martin’s Press

Natural Experiments of History: Jarod Diamond and James Robinson, Belknap Press

Sapiens – A Brief History of Humankind: Yuval Noah Harari, 2015, HarperCollins Publishers


Watson and Crick

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