Evolutionary Medicine

Objectives and Rationale

My goal is to develop an integrated curriculum unit to use with my fourth grade students to teach events in history that were influenced by viruses and disease. We will work on the unit for four weeks and will combine both social studies and science.

The students will learn three main principles of evolutionary medicine. First, students need to understand how people develop immunity against infectious diseases. The second principle is the relationship between population size and disease spread. The third principle is the interaction between invasive and native species and how invasive species impact biodiversity. These three guiding principles will lay the foundation for this unit. In a world full of supergerms, MRSA bacteria and widespread antibiotic resistance it is important for students to understand how bacteria, viruses and human immune systems evolve.

Once the students have a working knowledge of these principles, we will examine how the Native Americans came to North America, and how the migration from Siberia to North America kept them isolated from many infectious diseases for thousands of years. We will also delve into the reasons why their isolated lifestyle made Native Americans more vulnerable to so many Old World diseases.

Next, we will examine the colonization of Virginia and the role that disease played for the English settlers, Africans and the Native Peoples. Beginning when the Old and New World's collided, the unit will introduce factors that play a role in disease transmission and vulnerability and will focus on the importance of population density, diversity, the domestication of animals and agriculture. Students will understand how Europeans and Africans brought diseases that were new to the Native Peoples. They will learn how the lack of immunity hindered the ability of the Native Peoples to resist diseases. By studying maps and graphs of English and Native American populations over time, the students will be able to draw conclusions and make inferences to explain the shift in the populations. They will conclude that the English settlement was able to spread as a result of disease. It is important for the students to understand the importance of the first permanent English settlement and the implications of its survival. It is also important for my students to understand how the arrival of the English colonists was the beginning of the demise of the Native Americans.

The spread of Old World diseases haunted the Native American population for many years. Major outbreaks that impacted the Native Americans were diphtheria in 1614 and measles in 1618 in Peru and Mexico respectively. These two epidemics resulted in the death of 10-20 million Native Americans. A similar story would unfold in the United States of America beginning during its early colonization. In 1618, smallpox ravaged the Massachusetts Bay Native Americans. Disease took its toll and made the removal of the Native People easier for newcomers. Jared Diamond stated, "Far more Native Americans died in bed than on the battlefield— the victims of germs, not of guns and swords. Those germs undermined Indian resistance by killing most Indians and their leaders and by demoralizing the survivors." ²

The theme of disease will reemerge during our Civil War unit later in the year. Connections will be made to the impact of measles during the Civil War and to the urbanization of Virginia during the post -Civil War era. By making these connections the students will understand how cultural evolution leads to the evolution of disease and changes history.

Numerous social studies objectives will be covered in this unit including: the colonization of Jamestown and Virginia, westward expansion, economic development and transition and advances in transportation and technology. The science objectives this unit will address are: ecosystems, natural resources and scientific investigations. Beyond the prescribed curriculum, my intent is for the students to develop an understanding of evolutionary medicine that can be applied to the world around them.

This unit will teach my students the importance of examining our history to learn about the present. While my students seem to really enjoy social studies, they often do not grasp the connection to their own world. From a teacher's perspective, it often is challenging to connect the social studies and science curriculum in a natural way. The connections that will be made in this unit will be meaningful and natural. More importantly, the students will develop their higher level thinking skills as they transfer their social studies knowledge and apply it to make sense of science concepts. For example, my students will understand that the Europeans were the invaders who displaced the Native Americans' population. My students will also make the analogy that in ecosystems foreign invaders often wipe out and displace native populations. One example is the Snakehead fish. This type of fish is not native to the Potomac River. Therefore it has no known predators and resides at the top of the food chain, thus preying on other organisms in the river. In addition to foreign species, there are also foreign diseases. MSX is a parasitic disease that was probably introduced to the Delaware Bay when Japanese oysters were introduced. MSX has spread and is also in the Chesapeake Bay. This parasite has been destroying much of the native oyster population that had no prior immunity to this disease.

Once the students have an understanding of evolutionary medicine concepts and have used them to look at historical events, they will be asked to apply this knowledge to their science curriculum. In this phase of the unit, the students will apply their newly learned concepts as they study ecosystems and conduct scientific investigations. The students will understand how Old World pathogens inoculate native fauna and flora in the New World. Historical examples will be used to illustrate the connection between the spread of disease from Europeans and Africans to the Native Peoples, and the spread of an invasive species that displaces a native species. Students will examine specific examples of invasive species both from the past and today. One example such as how the introduction of Chinese chestnut trees brought a fungus, Cryphonectria parasitica, which was spread by woodpeckers and nearly wiped out the American chestnut species. ³ Another example is found in the Chesapeake Bay ecosystem. MSX and Dermo are invasive parasites that have destroyed 90% of the native oyster population. I would like my students to see how invasive species decrease biodiversity and create monocultures as well as understand that homogeneity is just as problematic to an ecosystem today as it was to the Native Americans. Teaching the basic understanding of disease transmission and species susceptibility will enable my students to apply three major principles of evolutionary medicine across disciplines and through time. The ultimate goal will be for the students to apply concepts to the world around them.