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Scientists have discovered a previously unrecognized genus of extinct horses that roamed North America during the last ice age. The new findings are based on an analysis of ancient DNA from fossils of the enigmatic 'New World stilt-legged horse'

Millions of people in 70 countries across Asia, Africa, and South America have been exposed to high levels of mercury as small-scale mining has proliferated over the past decade. The United Nations Environment Programme estimates that at least 10 million miners, including at least four million women and children, are working in small "artisanal" gold mines, which produce as much as 15 percent of the world's gold.

The U.S. is one of the richest countries in the world, yet we rank 29th for life expectancy. We spent more than twice what other countries spend per capita on health care. Why aren't we healthier?

That's why the annual County Health Rankings are important. They not only show health standards at a local level-they also show the multiple factors that pertain to health outcomes, everything from racial segregation and sleep patterns to smoking rates and access to decent food.

Fact sheets explain ecological issues, define terms and concepts, and provide references for additional information.

This interactive case discussion was created to emphasize the clinical relevance of population genetics, but is also a suitable resource for teaching the basic principles of population genetics while relating them to human genetic variation. Our understanding of human genetic variation has deepened over the past decade due to fine-scale genome mapping. Applying this knowledge to the evaluation of ancestry-based genetic testing strategies, such as direct-to-consumer genetic testing, is an important component of the practice of culturally-competent medicine and a relevant way to teach the foundations of population genetics, including Hardy-Weinberg equilibrium.

his resource describes an inquiry-based, in-class exercise designed for students working in small groups. It is designed to review and enrich student understanding of probability, how probabilities of individual events can be combined to make predictions about more complex outcomes, and how observed data can be compared to a null model based on probabilities using a chi-squared test. These skills are used extensively for classical genetic analysis. Throughout the activity, peers and instructors guide students through the process of developing and solving problems using probabilities and chi-squared tests in small groups.

Germ theory states that specific microscopic organisms are the cause of specific diseases. The theory was developed, proved, and popularized in Europe and North America between about 1850 and 1920. Because its implications were so different from the centuries-old humoral theory, germ theory revolutionized the theory and practice of medicine and the understanding of disease. It was, however, compatible with existing ideas about health, especially those associated with 19th-century hygiene and sanitation.

This flipped clicker case study explores the fascinating relationship between the Arizona Bark Scorpion (the most venomous scorpion in North America) and the Southern Grasshopper Mouse. Initially it would seem that the grasshopper mouse is no match for the scorpion's venom; however, the grasshopper mouse is easily able to eat the scorpion and is largely immune to the scorpion's sting. By working through this case study, students learn about neuron anatomy and physiology as they explore how the grasshopper mouse is able to survive the scorpion's venom. This case study was developed for an introductory biology course for majors, but it could also be used in an introductory biology course for non-majors or in an anatomy and physiology course. The case requires that students learn basic neuron anatomy and action potential physiology prior to class by reading their textbook or by watching videos on the subjects. An optional set of guided questions tailored to Campbell Biology (10th ed.) is included in the teaching notes.

This lesson, using segments from the PBS series Faces of America, explores the various types of genetic information contained in the human genome. The Introductory Activity examines the structure and composition of chromosomes and DNA, and can be used as a review or introduction to the topic. Following that, students will participate in a hands-on activity reviewing basic Mendelian genetics and the difference between genotype and phenotype. Students will also learn about different ways of tracing ancestry through DNA, and apply that to patterns of human migration and genetic population sets known as haplogroups. In the Culminating Activity, students will develop methods for determining the genetic heritage of their class, school, or community.

This activity guides the analysis of a published scientific figure from a study that modeled the impact of an infectious fungal disease on a bat population. In 2006, a disease called white-nose syndrome (WNS) began wiping out bat populations in North America. Because many of these bats eat insect pests, the spread of WNS may devastate ecosystems and increase pest control costs. In this study, scientists mathematically modeled the effects of WNS to estimate extinction probabilities for the little brown bat (Myotis lucifugus) population in the northeastern United States. This figure shows these probabilities projected for five annual rates of population decline. Each projection is simulated up to 100 years after WNS emerged in the population. The "Educator Materials" document includes a captioned figure, background information, graph interpretation, and discussion questions. The "Student Handout" includes a captioned figure and background information.

Overview of cancer with animation and basic explanation 5:00min

High on Bolivia's semiarid Andean plains at more than 12,000 feet and subject to climatic whims, the shallow saline lake has dried up before only to rebound to a size twice the area of Los Angeles. But recovery may no longer be possible, scientists say. "This is a picture of the future of climate change," said Dirk Hoffman, a German glaciologist who studies how rising temperatures from the burning of fossil fuels has accelerated glacial melting in Bolivia.