Why Did the Anasazi Abandon Mesa Verde

Many middle school curricula include attention to ancient American people and their cultures. This blog entry may be helpful in making connections to the nature of science and scientific enterprises as part of an integrated approach in studying the Anasazi or ancient Pueblos. The story titled “Vanished: A Pueblo Mystery,” published in the New York Times, April 8, 2008, enlightens readers regarding the science of archaeology.

Archaeologists rely on empirical evidence to reconstruct past events. However, this empirical evidence does not normally emanate from controlled laboratory experiments, conceived of and performed at the scientists’ will. Rather, archaeologists use evidence left by the activities of not only people that lived long ago but other organisms as well. They must be skilled observers.

The graphic accompanying the article shows where the Anasazi migrated from–what is now southwestern Colorado–and where they migrated to–what is now the Davis Ranch and Tucson, Arizona, area. There is also a slide show of images of dwellings among other relevant artifacts. For archaeologists interested in this part of the world and these people, the article states, “the most vexing and persistent question in Southwestern archaeology [is]: Why, in the late 13th century, did thousands of Anasazi abandon Kayenta, Mesa Verde and the other magnificent settlements of the Colorado Plateau and move south into Arizona and New Mexico?”

This is not the first time this question has been asked or that an answer has been proposed based on evidence. For example, drought has been documented during this time, providing a seemingly good explanation for the migration. However, evidence suggests many people were able to survive the drought. That fact casts doubt on drought as the only cause for the migration. Further, the area the Anasazi migrated to was actually drier than that which they migrated from.

An alternate hypothesis is based on the pollen record. “Measurements of the thickness of pollen layers, accumulating over decades on the bottom of lakes and bogs, suggest that growing seasons were becoming shorter.” Even this fact in combination with the relatively short drought does not convince many archaeologists these were the reasons for the migration. Why did the Anasazi never return, even when the drought ended? Evidence suggests they did not leave in a hurry, but planned their exit as if they intended to return.

Even more interesting hypotheses are presented regarding the role of religion in the migration. Donna Glowacki, an archaeologist at the University of Notre Dame, cites evidence that suggests the early culture of the group, prior to the migration, included a tradition where only a select, privileged few had access to the largest, most well-equipped dwellings. She asserts a change can be detected after the migration in the southern villages. There evidence indicates fewer of these select kivas are found, suggesting there was less reverence for a select few. The article indicates this change could be analogous to the Protestant reformation.

So who’s right? Well, no one knows for sure, but the Village Ecodynamics Project is set to bring together these various hypotheses to see if a coherent, though probably somewhat complex explanation, or theory, can be constructed. The researchers will use evidence of “rainfall, temperature, soil productivity, human metabolic needs and diet, gleaned from an analysis of trash heaps and human waste” to reconstruct events and come to conclusions.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The article illustrates well the nature of science. Our understanding of the Anasazi migration is undergoing revision in light of new evidence and reinterpretation of existing evidence from new perspectives. It calls attention to the various scientists working on the same project, each contributing unique expertise and building new knowledge. The article conveys several possible hypotheses, all of which need to be thoroughly investigated to see if any can be discarded. It underscores that scientists don’t have definitive, pat answers, only best guesses based on reasonable interpretations of much evidence. Several kinds of, or sources of, evidence are identified giving readers an indication of the nature of archaeology in particular.

Ask students to describe archaeology. Affirm their responses and ask them to elaborate as much as they can. They should use terms like ancient, culture, science, observation, inference and reconstruct. Ask students what kind of knowledge or skills a good archaeologist needs. They should include knowledge of anatomy, plants, and history, and excellent observational skills. Archaeologists need to be global thinkers, able to see relationships among seemingly disparate observations. They should be good team players. If needed, ask leading questions such as: What other fields of science might be related to archaeology? They should include botany, zoology, and anthropology even if they don’t use those names for them.

Explicit connections to life science and earth science can be made, particularly to botany and climate. Ask students how knowledge of the growing season can be inferred from the pollen record. How can inferences regarding wet or dry years be obtained from tree rings?

Here are some additional resources related to the nature of science and fields of science: Science Sampler: Jumping to the Right Conclusions, Inferences, and Predictions;  Presenting a Logical and Reasonable Case Using Logical and Reasonable Arguments; Frequently Asked Questions: Questions about Paleontology.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published April 11, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

After 50 Years, Scientists Still Not Sure How DEET Works

DEET (short for N,N-diethyl-meta-toluamide) is the most widely used insect repellent in the world for a very good reason – it works really, really well! Just a quick spray on exposed skin keeps mosquitoes, flies, fleas, chiggers, and ticks away. Developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946, millions of people worldwide use DEET to ward off vector-borne diseases. First of all, why would researchers study DEET if it works so well? While DEET is an effective repellent, it doesn’t work against all bugs, it’s corrosive to plastics and there are concerns about its effect on human health.

 

Structural Formula for N, N-diethyl-meta-toluamide (DEET).
Courtesy of Wikipedia – Click on the image for a larger version.

How DEET actually works has puzzled scientists for more than 50 years. Scientists long surmised that DEET masks the smell of the host, or jams or corrupts the insect’s senses, interfering with its ability to locate a host. Mosquitoes and other blood-feeding insects find their hosts by body heat, skin odors, carbon dioxide (breath), or visual stimuli.

Amazingly, within a few months this year, scientists from two different labs have come up with competing explanations of how DEET works. In March of 2008, researchers at Rockefeller University in New York, said that DEET jams odorant receptors in insect nervous systems, in effect masking odors that would ordinarily attract the bugs. According to Dr. Leslie B. Vosshall, a researcher who worked on the project, now that they know that DEET targets OR83b co-receptors, they can quickly screen thousands of other compounds in hope of finding one that is even more effective and has fewer disadvantages.

Are you sure, ask researchers at the University of California, Davis? Mosquitoes flee because of their intense dislike for the smell of the chemical repellent and not because DEET jams their sense of smell. In August 2008, in a paper published in The Proceedings of the National Academy of Sciences, they provide a simpler explanation. Mosquitoes, they say, smell DEET directly and avoid it.

Dr. Vosshall, involved in the earlier study, said that her team stood by its work, and that its findings were based on a variety of experiments. So for now, the jury is still out.

Connecting to the National Science Education Standards

These competing explanations on how DEET works provides a perfect example of one aspect of the nature of science – Scientific Claims are Subject to Peer Review and Replication. Researchers in labs across the world work on answering many of the same questions. The results of their work are published in peer reviewed journals so that researchers around the world can examine their data and logic, identify alternative explanations, and replicate observations and experiments. Peer review is an integral part of genuine scientific enterprise and goes on continuously in all areas of science.

The National Science Education Standards in the History and Nature of Science Content Standard G describes what middle school students should understand about this part of the nature of science, including:

It is normal for scientists to differ with one another about the interpretation of the evidence or theory being considered.

Different scientists might publish conflicting experimental results or might draw different conclusions from the same data.

It is part of scientific inquiry to evaluate the results of scientific investigations, experiments, observations, theoretical models, and the explanations proposed by other scientists.

Although scientists may disagree about explanations of phenomena, about interpretations of data, or about the value of rival theories, they do agree that questioning, response to criticism, and open communication are integral to the process of science.

Additional Resources

Read the entire National Science Education Standards online for free or register to download the free PDF. The content standards are found in Chapter 6.

Science For All Americans Online: The Nature of Science
Science for All Americans consists of a set of recommendations on what understandings and ways of thinking are essential for all citizens in a world shaped by science and technology.

Household Product Database
List of products that contain DEET.

Chemical Technical Summary for Public Health and Public Safety Professionals
The Department of Health and Human Services provides a summary of all medical cases and research done on DEET.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Kimberly Lightle and published August 26, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/19/12 by Jessica Fries-Gaither.

The Relationship Between Sea Surface Temperature and Hurricane Activity

Is your unit on climate and weather approaching? Here’s some research you can use to enrich students’ understanding of weather. It can help you make real-world connections from the textbook and classroom to the research scientists working to understand the science of hurricanes.

The news comes from ScienceDaily. The article, Increased Hurricane Activity Linked to Sea Surface Warming, explains how two variables, sea surface temperature and atmospheric wind field, were used to model the conditions under which hurricanes form. When they focused on temperature, the researchers found that a small increase in sea surface temperature, 0.5 degrees C, had a large impact on hurricane activity.

Mark Saunders, one of the researchers from University College London, emphasized,

Our analysis does not identify whether greenhouse gas-induced warming contributed to the increase in water temperature and thus to the increase in hurricane activity. However, it is important that climate models are able to reproduce the observed relationship between hurricane activity and sea surface temperature so that we can have confidence in their reliability to project how hurricane activity will respond to future climate change.

An impressive, aggregate satellite photo of several hurricanes in the Gulf of Mexico during 2005 accompanies the article. There are also links to several recent, related stories.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

This news article connects directly to the Earth and Space Sciencecontent standard for grades 5-8 of the National Science Education Standards, which includes this fundamental concept: “Global patterns of atmospheric movement influence local weather. Oceans have a major effect on climate, because water in the oceans holds a large amount of heat.” The reported research also connects to the Science as Inquiry content standard.

If your students already have a good understanding of the science of hurricanes, ask them what they think would be different about the world’s hurricanes if the sea surface temperature increased just a half degree C. How do they think one could investigate that question? What other variables need to be considered? What other existing evidence could be used to inform one’s hypotheses? Suggest that they might look at the history of hurricanes and the sea surface temperature conditions under which they formed. Why would such an investigation be potentially useful?

Then show them the brief article and ask, What do you think Saunder’s intention was when he said, “Our analysis does not identify whether greenhouse gas-induced warming contributed to the increase in water temperature and thus to the increase in hurricane activity?” Lead students to the related ideas of methods of science, which include making inferences supported by the evidence. This research did not investigate what might contribute to sea surface temperature increases, only the effects of sea surface temperature increases.

Here are some additional resources that are part of the Middle School Portal 2 collection to facilitate your instruction regarding weather and climate:

 The Powerful Punch of  a Hurricane; El Nino and His Sister La NinaTracking El Nino; Detecting El Nino in Sea Surface Temperature DataOceans, Climate and Weather; Earth’s Oceans, and Ocean Temperatures.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published February 7, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 3/27/12 by Jessica Fries-Gaither.

Newest Issue of Beyond Weather and the Water Cycle Highlights the Science of Climate Study

Scientists recording data on Sperry Glacier. Photo courtesy of glaciernps, Flickr.

The just-published issue of the free, online magazine Beyond Weather and the Water Cycle gives K-5 school teachers a unique opportunity to introduce the science behind weather and climate change to young students with engaging lessons and proven reading strategies.

Each issue of the magazine takes its theme from one of the widely accepted principles of the climate sciences. The theme of the September 2011 issue is “We Study Earth’s Climate.”

Designed to integrate science and literacy instruction for educators in K- grade 5 classrooms, this and earlier issues provide background articles on the related science and literacy topics and their connections to the elementary curriculum. Science and literacy lessons to use in the classroom become a part of unit plans for grades K-2 and 3-5 and are aligned with the national standards for science education and English language arts.

An original story, titled  How Do We Study Climate?, gives young listeners and readers chances to use their comprehension skills on informational text. The story is available at two reading levels and in three different formats.  Selected children’s books on climate and weather are highlighted in a bookshelf feature.

Two articles are devoted to teaching young people to evaluate information from web sites and to use video clips from agencies that work with weather satellites, balloons, and buoys to learn about data collection.

Readers are welcome to add their ideas and suggestions on articles by leaving comments. They can also easily share and bookmark content by using the embedded AddThis buttons.

Beyond Weather and the Water Cycle is funded by a grant from the National Science Foundation (NSF) and produced on the campus of The Ohio State University (OSU) in Columbus, Ohio.  All past issues of the magazine are available from the homepage of the magazine.

Kimberly Lightle, director of digital libraries in OSU’s College of Education and Human Ecology, School of Teaching and Learning is the principal investigator of the project as well as a contributing writer. Jessica Fries-Gaither is the project director of Beyond Weather and the Water Cycle as well as the award-winning sister publication, Beyond Penguins and Polar Bears.


We Want Your Feedback
We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org. Post
updated 12/07/2011.

Forensic Science: A Hit in Middle School, Maggots and All

The latest online publication from the Middle School Portal is now available – Forensic Science: Middle School. We’ve searched the web for the best resources associated with this topic but I’m sure we haven’t found all the great ones. We’d like your help – do you know of other resources we should include? If you include Forensic Science topics in your curriculum we’d sure like to hear how you do it – please join in the conversation at the Middle School Portal 2 social network – http://msteacher2.org!