Overview
Students in Florida are assigned to schools based on geographic location. They are then randomly placed in classes, unless they are in advanced classes. All schools in Florida base their curriculum and instructional strategies on the Sunshine State Standards. The Sunshine State Standards are set details, concepts or facts that the students must learn. The comprehension of these standards is tested on the Florida Comprehensive Academic Test or FCAT. Students must pass the FCAT test in reading and math in 10th grade and in science in 11th grade.
This curriculum unit is intended for Biology students, grades 9-11. The students are varied in learning abilities, from FCAT (Florida Comprehensive Academic Test) level 1 through level 4 in reading. Level 1 students read 2 years or more below grade level, level 2 students read 1 year below grade level, level 3 students read at grade level and level 4 students read 1 year above grade level.
This curriculum unit can be taught to standard mainstream students as well as honors or advanced students. They also vary in their learning preferences. Some are kinesthetic learners, those who learn by doing and touching. Still others are aural and learn by hearing or are visual and learn by seeing. This curriculum unit can also be used for ESOL (English Speakers of Other Languages) students, by incorporating the vast amount of Mexican art and the use of graphs and charts for population statistics.
This curriculum unit incorporates a cross curricular approach to learning. The students will learn about population dynamics by investigating the history of early Americans, reading early accounts of the Spanish invasion, analyzing and discussing Mesoamerican art, and graphing population numbers. This type of approach integrates history, reading skills, art, and math with science. This type of interdisciplinary planning fosters a stronger continuity among the core subjects. They will also use numerous reading and comprehension strategies which will increase their reading abilities.
Students will begin their study of early Mesoamerica by focusing on the Aztec people and different factors affecting their population size and changes to that population size.
I will introduce the students to a brief history of the early Mexican people focusing on the Aztecs. The fall of the Aztec empire will be discussed in relation to Cortés and the diseases that were prevalent in the 1500s.
The students will be introduced to terminology relative to population dynamics and demography. They will relate these terms to the situations that occurred before, during and after the fall of the Aztecs during the Spanish conquests. The students will construct population graphs illustrating the population decline over a hundred year period. They will discuss the factors influencing this population decline and discuss how humans have affected other populations and environments world wide. All of these concepts will be addressed through cooperative learning strategies and modeling activities.
In 1492 Columbus Sailed the Ocean Blue, and With Him He Brought Disease and Pestilence.
History of the Mesoamerican People
The area known as Mesoamerica refers to the geographic area and cultural traditions of the pre-Columbian civilizations of North America. This area included Mexico and parts of Central America (Mckay, Hill and Buckler, 1992). Areas in lowland districts tended to have heavy rainfall and warm temperatures which tended to foster disease (Cook, 1998).
Early Mexican peoples lived simply. They began as hunter gathers and converted to agriculture and cultivation around 8000 B.C. One of the earliest crops that was domesticated is believed to be the bottle gourd. It was useful for holding water and other liquids. Their main crops included maize, beans and squashes (Mckay, Hill and Buckler, 1992). They ate cacao beans, maize, manioc (also known as cassava), avocado, beans, pumpkins, chili peppers, and tomatoes. Beans were especially rich in protein as well as oils and carbohydrates (Crosby, 1972). There was very little animal protein in their diets. They ate rabbits, turkeys, lizards, fish and other small mammals they could hunt. They were poor domesticators of animals. They only had small dogs, turkeys, guinea pigs, Moscovy ducks. Although there were many important ancient Mexican civilizations, the Aztecs are not only the best known, but also the last.
North of the Basin of Mexico lived nomadic hunters. They were called Chichimec, or dog people. At the start of the 13th century some Chichimec came to settle around Lake Texcoco. This group of Chichimec was called Mexica. They claimed to be from Aztlan, the place of seven caves (Schwartz, 1997). In 1325 the Mexica, now know as the Aztec, formed their capital, Tenochtitlan, which is the location of present day Mexico City (Mckay, Hill and Buckler, 1992). Their city grew from a small town to a large city with stone temples and adobe houses. They began to extract tributes from surrounding provinces under their control and participate in long distance trade (Schwartz, 1997). Despite their achievements, at the heart the Aztecs were an agricultural society that was greatly influenced by the forces of nature.
The Conquest of the Aztecs
During the Spanish Conquest of the New World there were several stages of Spanish expansion. The Aztec invasion by the Spanish represented the second stage, the first having taken place a generation before in the Dominican Republic and Cuba (Mckay, Hill and Buckler, 1992). Hernan Cortés, Spanish conquistador, set sail in February of 1519 with about 600 men, cannons and horses.
On his way, he picked up Jerónimo de Aguilar, a long-shipwrecked priest who had learned to speak Mayan, who would be a translator. They landed near Vera Cruz on the Gulf Coast. Cortés marched inland battling native peoples on his way to the Aztec capital. Many of the natives fled in fear for they had never seen horses before. During their journey they encountered the Tlaxcalan people; they initiated battles with the Spanish invaders but after weeks of heavy fighting the Tlaxcalans surrendered. They became allies of the Spanish and would help conquer the Aztecs.
On November 8, 1519, Cortés met Montezuma, the Aztec ruler, outside the city. Montezuma received the Spanish graciously. Montezuma initially believed that Cortés might be Quetzalcoatl, an ancient god (Mckay, Hill and Buckler, 1992). Cortés still believed the Aztecs would drive them out so he captured Montezuma to be his hostage. A young woman who had been given to the Spanish, Marina, spoke Mayan and Nahuatl, the Aztec language. Although cumbersome, Cortés could speak to Aguilar, Aguilar to Marina, and Marina to Montezuma. This allowed many opportunities for mistranslations.
Six months later, while Cortés was away, Alvarado, one of Cortés's men, slaughtered hundreds of Aztecs out of fear, initiating an Aztec uprising. When Cortés returned he was allowed into the city, but he was attacked. Montezuma tried to persuade his people to surrender; they in turn stoned him to death.
On June 30, 1520, called Noche Triste, or sad night, the Spanish fled, still being pursued by Aztec warriors who killed many of their men. Cortés regrouped over the summer of 1520 and in May 1521 he surrounded the Aztec capital. He cut off their supplies and after three months the city fell, ravaged by disease and dysentery (Mckay, Hill and Buckler, 1992).
The Spanish were able to conquer a civilization that was known to be fiercely militaristic and had a population of millions. They appeared to have few advantages when they arrived: 600 men, and a few cannons and horses. But what they lacked in numbers and supplies they made up for with viral and bacterial immunities. The epidemic that swept through the Aztec empire decimated the population, leaving the survivors dispirited. They were plagued by an illness that mysteriously killed Indians and spared the Spanish, making the Spanish appear invincible (Diamond, 1997). As a result the Aztec's were ready for invasion.
Before and after the conquest of the Aztec, the Spanish favored a policy of settlement, or congregaciones, where the natives were forced together in a sort of town. This increased the density of the population causing future epidemics to have higher mortality (Cook, 1998). These types of settlements were favorable to the Spanish political, economic and religious control (McCaa, 1997).
Disease in the New World
The New World was not disease free. Its people were affected by syphilis and other infections (Cook, 1998). Because of the great isolation of the Mesoamerican people their immunity to certain world disease had been reduced. When the New World met the Old, the Spanish conquistadors and explorers brought with them fatal diseases that killed more effectively in the New World (Crosby, 1972). The highest mortality was during the first hundred years of contact. The diseases spread quickly, killing large numbers of natives. Estimates vary considerably, with one estimate suggesting a drop from 25 million in 1519 to 1 million in 1620 (Mckay, Hill and Buckler, 1992). After several generations, some resistance was built up among survivors, and interbreeding among them (Crosby, 1972). There were two main diseases that caused so much damage: smallpox and measles.
Smallpox began to ravage the Aztec population around 1520, about the time of Noche Triste. Smallpox is transmitted through the air in droplets or dust particles and enters a person through the respiratory system. It is extremely communicable. It incubates in a host for up to twelve days. The host begins to have a high fever with vomiting. Four days later pustules on the skin begin to form. For those who survive, within a week the pustules scab up and leave scars. Within a month or less the patient is either dead or has developed immunities (Crosby, 1978).
Measles arrived around 1531. The disease was described as a small skin rash that affected all sectors of the populations (Cook, 1998). The mortality experienced by this disease was less than small pox but still devastating. The mortality rates were around 25-30%. Measles has a shorter lifespan than smallpox and survivors develop immunities.
Malaria may have been introduced during Columbus's 4th expedition. Some of the explorers carried Vivax malaria, endemic in Mediterranean Spain, in their blood (Cook, 1998). The explorers reached Jamaica in 1503, after coasting along Mesoamerica. Mosquitoes were very abundant and several varieties of the Anopheles mosquito could carry malaria; they only needed the introduction of the parasite from an infected sailor (Cook, 1998). Malaria exhibited a different pattern of transmission compared to measles and smallpox. New cases of malaria may appear during any time of year in any area whereas epidemic diseases like smallpox and measles have a lot of cases for a time then no cases for a while (Diamond, 1997). Taken together, the various epidemics caused a massive loss of life which made it easier to conquer most of the hemisphere (Cook, 1998). Disease was not the only cause for death in the New World; non-native species also had a major impact.
Non-native Species Introduction
The Europeans also disrupted the ecological balance of the ecosystem that existed in the New World. They brought with them a variety of plants and animals. They introduced horses, large dogs, pigs, cattle, chickens, sheep and goats to the New World. These animals had no natural predators in their new environment and no New World diseases affected them. This allowed the population of these introduced species to soar. The pig, especially, adapted remarkably (Crosby, 1972). Due to their remarkable growth they caused the extinction of native species of plant, animal and even the natives themselves by eating their crops.
The introduction of grazing animals also caused mass deforestation and habitat destruction. The Spanish also set aside large areas for grazing, usually where the Indians land where they had been cultivating their largely vegetarian diet. Indians went hungry and had a lower disease resistance. Many left or died.
The Spanish also brought over their own domesticated dog. Their dogs were much larger and more ferocious than the dogs that existed in the New World. They brought Mastiffs and greyhounds that were trained for war and killing people, especially Indians (Schwartz,1997). The dogs were used for many tasks: food tasters, hunting game, guarding, tracking natives, and in war, killing large numbers of people (Schwartz, 1997). Some of them returned to the wild and lived as predators. They were treated like wolves by the natives. These introduced animals also brought their own diseases with them. In South America, the native alpaca and llama population suffered greatly.
They also brought a variety of plant life. They brought wheat, chickpeas, olives, melons, onions, radishes, salad greens, grape vines, sugar cane, and fruit (Crosby, 1972). But not all of these imports would grow in the New World Climate. Often the Native population was forced to grow European crops when the Spanish could not grow enough of their own. But rarely did the Natives add these to their own diets (Crosby, 1972).
Some of these imported animals were not brought over intentionally. The black rat hitched a ride over and spread out all over the continent. They ate whatever they could find. They were also carriers of diseases, the bubonic plague and typhus (Crosby, 1972). Many of the plants that came to the New World that were not food plants or floral were also unintentionally brought over. They came hidden in cloth, mud, dung, and other ways. With the overgrazing done by the imported livestock, heartier foreign grasses and weeds were able to take over. Kentucky Bluegrass, dandelions, and daisies were some of the plants that originated from the old world (Crosby, 1972).
Population Dynamics
Population growth is the change in population size over time (Glencoe, 1998). But this growth is affected by limiting factors, that is, factors that determine whether an organism can live in an environment (Glencoe, 1998). These limiting factors help define the carrying capacity of the environment.
The carrying capacity is the number of organisms the environment can support over time. Populations generally increase exponentially, at an ever-increasing rate, until acted on by outside forces. The population then levels off and is maintained just below the carrying capacity of the environment. Density dependent and density independent factors both regulate the size of a population.
Density dependent factors have a greater effect on more dense populations. Thy have an increasing effect as the population increases. These factors include such things as disease, competition, parasites, food availability. Density independent factors affect the entire population regardless of size or density. These are usually things such as natural disasters, floods, volcanic eruption, drought, and habitat destruction. No matter how many individuals are living in the valley, if it floods they all will die. Conquest may even be considered density-independent as many settlements and cultures were affected.
Age Structure
The age structure of a population refers to the proportion of individuals in their pre-reproductive, reproductive, or post-reproductive years. Depending on the number of individuals within each structure you can determine whether a population is growing or not. The age structure of Mesoamerica was young, with 40% of the population under 15 years and 90% under 50. Though the average life expectancy was 16 to 26, the population could sustain a growth rate of 0.5% a year if there was a high fertility rate (McCaa, 1997).
Species Interactions
The interaction of different species also affects the population size. If a new species of animal is introduced into a population, such as a pig, then this species grows exponentially until it reaches its limit or the carrying capacity of the environment. This pig will compete for food with the native creatures and with the native Indians. They may also cause the extinction of native plants and animals due to this competition. Introduced species may also hunt native species, such as the large dogs that the Spanish brought. Due to competition, the native species that was food for a native predator may die out, causing the extinction of the native predator.
Stress
Stress is also a major factor that affects population size. Though the mechanisms and factors that cause stress are not well understood, it has been shown that populations under sever stress will exhibit a variety of symptoms. Decreased parental care, decreased fertility, and a decreased resistance to disease have all been shown.
The Mesoamericans were under tremendous stress with their foreign invaders all around them who introduced new animals, plants, religion and practices. Women were known to interrupt pregnancies or abandon babies so that they would not experience the same fate as the parents (Cook, 1998). After being infected with smallpox and surviving, the victim is left scarred for life. The psychological affects of this disfiguring disease were dramatic. The smell of the deceased was so great in some areas their houses were pulled down on them or they were cast into the water (Crosby, 1978). All of these things left the people distraught, terrified and depressed. The extreme physical exertion, anemia from nutritional deficiencies, and parasitic infection combined with disease and conquest made for an extremely stressful existence in Mesoamerica (McCaa, 1997).
Ecological Impact
All organisms are interdependent upon one another. Changes in any ecosystem can have unpredictable and detrimental effects on the entire system. Humans, past and present, are the main reason that our environmental support system is at risk. Human's themselves make up one part of the earth's biodiversity. This relates us to every other organism of the earth, either directly or indirectly (Leonard and Penick, 1995). Humans destroy the biodiversity of the planet that is a product of millions of years of evolution, essentially irreplaceable losses. Many species in the Mesoamerican region went extinct with our knowing they ever existed.
The habitat destruction, introduction of non-native species into the Mesoamerican ecosystems and overexploitation of species in Mesoamerica resulted in a tragic loss of biodiversity including the extinction of some native cultures. With the introduction of non-native species an ecological imbalance occurred. These new species compete with the current species and are often associated with their extinction. The ecological disruption that occurred in Mesoamerica caused many Aztec and other Mesoamerican people to die due to starvation and disease. Introduced species ate their food crops, pushed out their native animal resources.
As humans, we need to know about diversity and past mistakes so that we may coexist with other species and make changes that may one day be essential to our own survival.
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