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5:11 video Chat with a friend about an established scientific theory, and she might reply, "Well, that's just a theory." But a conversation about an established scientific law rarely ends with "Well, that's just a law." Why is that? What is the difference between a theory and a law... and is one "better"? Matt Anticole shows why science needs both laws and theories to understand the whole picture.

Science is working tirelessly night and day to disprove its own theories about how the universe works (or at least, that's what science thinks it's doing). Hank tells us a quick history of how we came to create and adopt the scientific method and then gives us a vision of the future of science (hint: it involves a lot more computers and a lot less pipetting).

This case is an account of the events that led Drs. Robin Warren and Barry Marshall to the bacterial theory of ulcers. The two physicians refused to accept the standard explanations for what they had observed and instead developed an alternative hypothesis, saving countless patients from unnecessary pain and suffering. Along the way they transformed the way the medical community viewed peptic ulcer disease. The case shows the importance of curiosity, serendipity, and tenacity in scientific inquiry; how science is built upon the work of others; how assumptions can cloud people's views, leaving them closed to new ideas; and how scientific "truth" can and does change when faced with new data and new interpretations. It is appropriate for use in any course at the high school or undergraduate level that teaches students about the scientific method and/or the sociology, nature, and history of science.

Genetic and biotechnology can improve food security, the environment and public health. Yet dramatic innovation can lead to unintended consequences and present ethical challenges. In theory, the study of genetics and related cutting edge sciences are widely celebrated. But in practice, the words "gene" and "genetic engineering" often stir fear and misunderstanding when applied to biomedicine and farming. Intricate science scares people who don't understand risk and complexity. What is the potential of agricultural and human genetics? The commitment of the GLP is to promote public awareness of genetics and science literacy.

This case study introduces students to the "Red Queen Hypothesis." The hypothesis states that when two species compete for a limited resource or exist in a predator-prey relationship, in order for the antagonists to remain in relative population equilibrium, there must be ongoing and reciprocal adaptation on each side. If one species fails to adapt, it may quickly face extinction. Students are introduced to the Red Queen Hypothesis through an excerpt from Lewis Carroll's novel, Through the Looking Glass, in which Alice meets the Red Queen. They then review experiments from the research literature to evaluate the validity of the hypothesis in extant populations.  Students culminate their learning by contrasting their knowledge of the Red Queen Hypothesis to Darwinian evolutionary theory based on a passage from On the Origin of Species.  Students then craft a letter to Darwin helping to explain his "wedge" theory, a notion he originally developed but removed from later iterations of his book due to a lack of experimental evidence. Originally developed for advanced high school biology students, the case also may be used in a college-level introductory course on evolutionary biology.

Promotes accurate understanding and comprehensive teaching of evolutionary theory for a wide audience Explores the practical applications of evolutionary principles in daily life and the impact of evolutionary theory on culture and society throughout history Offers teaching tools such as unit and lesson plans and classroom activities, as well as additional online content such as podcasts and powerpoint presentations

In this case study students are provided with information for piecing together the story of how forest fragmentation and biodiversity loss can affect the risk of Lyme disease transmission to humans. The case introduces the dilution effect, a widely accepted theory-and one of the most important ideas in disease ecology-which suggests that disease risk for humans decreases as the diversity of species in an area increases. It also explains how landscape fragmentation, one of the most common threats to biodiversity, can influence the risk of Lyme disease for humans. Students interpret and discuss various figures to develop a concept map that connects all the individual results of the story. Students gain an appreciation for the complexity of species interactions in an ecosystem, the effects of forest fragmentation on these interactions and the possible consequences for human health. This activity was developed for an undergraduate introduction to environmental sciences course under the topic of biodiversity and conservation, but would also be suitable for interdisciplinary studies interested in examining the connections between conservation and public health.

The Ethics Primer provides engaging, interactive, and classroom-friendly lesson ideas for integrating ethical issues into a science classroom. It also provides basic background on ethics as a discipline, with straightforward descriptions of major ethical theories. Several decision-making frameworks are included to help students apply reasoned analysis to ethical issues. Although the Primer is designed for secondary school science classrooms, it has been used by teachers in a variety of classes and grade levels. It is particularly suited to social studies and integrated/interdisciplinary classrooms. It has also been used with adults. The Primer is not designed to be used cover to cover. Teachers should review materials and select lessons that fit their needs. The Primer is also intended to be used as a general resource, with a wide variety of topics.

When an elementary school teacher calls in sick to work, she finds out that she is not the only one who will be missing school that day.  Children from her fifth grade class have also become ill and parents are calling to report the absences. The concerned principal of the school finds out the fifth grade class had a field trip to one of the local parks the day before. The case shows the areas visited by the class and provides discussion between the principal and a physician that teaches the readers about water quality and EPA standards for bacteria levels in recreational water. The case has an optional lab component that provides the theory for three methods that can be used to conduct microbial water analyses.  Procedures are included for teachers to lead a lab activity to test water to identify which location in the park caused the illness. This case study and accompanying laboratory activity are recommended for an environmental engineering course or a lower level science course.

In a paper this week in Science, Vogelstein and Cristian Tomasetti, who joined the biostatistics department at Hopkins in 2013, put forth a mathematical formula to explain the genesis of cancer. Here's how it works: Take the number of cells in an organ, identify what percentage of them are long-lived stem cells, and determine how many times the stem cells divide. With every division, there's a risk of a cancer-causing mutation in a daughter cell. Thus, Tomasetti and Vogelstein reasoned, the tissues that host the greatest number of stem cell divisions are those most vulnerable to cancer. When Tomasetti crunched the numbers and compared them with actual cancer statistics, he concluded that this theory explained two-thirds of all cancers.

The theory of evolution by natural selection is simple, elegant, and profound. Yet, a large number of undergraduate students including biology majors, medical students, and pre-service science teachers maintain a large set of misconceptions that interfere with a solid understanding of the process of natural selection. It is also well known that lecturing is an insufficient strategy to help students confront and correct these misconceptions. This activity uses the evolution of coat color in oldfield mice (Peromyscus polionotus) as the basis of a case study in which students investigate the role of variation, heritability, and selection in the evolution of a trait. Students examine graphs, data, and excerpts from a series of papers that have been published about this system over the last 100 years. The content is delivered as an interrupted case and encourages peer-to-peer teaching and interaction. The case is appropriate for use in non-major, introductory, or advanced biology courses.

6 min video

Thankfully, Caleb Trujillo over at Molecular Life Sciences has created this handy infographic, that lists the top five misconceptions about evolution, and explains (with diagrams!) why they're wrong. And it's designed to be shared - as Trujillo explained over at Version 1.0 of the infographic: "From my experience, most people who misunderstand evolution are actually misinformed about what science is and how it operates."

It may sound radical, but it works: Eating peanuts slashes the chance of a peanut allergy, at least in children at high risk of developing one, a much-anticipated study finds. The results are likely to catapult a long-standing theory-that ingesting potential food allergens is a way to prevent allergies-into mainstream medicine. "This is the study," says Rebecca Gruchalla, a specialist in allergy immunology at the University of Texas Southwestern Medical Center in Dallas, who wasn't involved in it. The data, she says, are "just mind-blowing."

This clicker case addresses several important concepts related to evolution. First, it explores artificial selection and selective breeding. Charles Darwin used artificial selection as an example to support his Theory of Evolution by Natural Selection. Belyaev's Fox-Farm experiment is used as an example of a study that used selective breeding as the primary experimental procedure to investigate changes in a lineage. Second, it addresses an interesting observation made by Charles Darwin in The Origin of Species in which he noted how domesticated species also show interesting traits such as drooping ears which seem to be common in domesticated species. The "Farm-Fox Experiment" not only demonstrates how a research team can thoroughly investigate an intriguing question, but also serves as a classic example of elegant experimental design. Designed for use in a large introductory-level biology class, this case study would also be appropriate for smaller classes as well as for upper-level evolution courses.

Life on Earth is intimately connected to the natural cycles of light and dark that make up a 24-hour day. For plants, animals, and even bacteria, these circadian rhythms control many biological functions. Humans can overrule their body clocks, but at a price: People whose circadian rhythms are regularly disrupted-by frequent jet lag or shift work, for example-are more vulnerable to diabetes, obesity, cardiovascular disease, and cancer. There are various theories to explain these associations, and researchers now have a new player to consider: the bacteria that live in the digestive tract. According to a study in mice and a small group of human volunteers, the internal clocks of these gut microbes sync up with the clocks of their hosts. When our circadian rhythms get out of whack, so do those of our bacteria.

For years whale evolution was characterized by speculation and limited evidence. Evolution critics even focused on whales as a means to criticize evolutionary theory. Now whale evolution represents one of the best examples of "macroevolution." This "clicker case" uses this fascinating story of historical irony as a backdrop to the study of whale evolution. First, students study an array of whale fossils to learn how evolution is properly viewed as a branching, relationship-based process, not a linear, progressive, "chain-of-being." Using this view they learn how scientists seek to reconstruct past relationships and study transitional features, not search for "missing links." Students then learn that evidence for macroevolution relies on several lines of independent evidence from fossils, comparative anatomy, embryology, genetics, and paleoecology. With a focus on macroevolution, this case makes a critical contribution to evolution education. It could work well in a lower level undergraduate biology / evolution / paleontology course (non-majors or majors), or in an upper-level evolution course, perhaps early in the semester as a primer for related topics.

In 2005, PLoS Medicine published a now-famous paper with the attention-grabbing but exasperating title, "Why Most Published Research Findings Are False".1 It was written by John Ioannidis, MD, PhD, an American doctor from Greece, a distinguished author of about 400 peer-reviewed papers, 40 books and book chapters or so, and much more. Ioannidis is a giant, and I am really nobody to criticize.

Darwin's theory of biological evolution helps us understand how simple life forms can give rise to complex lifeforms, but how did the first reproducing creatures come about? The origin of life needs its own explanation.

A phylogenetic tree, also known as a phylogeny, is a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor. Phylogenies are useful for organizing knowledge of biological diversity, for structuring classifications, and for providing insight into events that occurred during evolution. Furthermore, because these trees show descent from a common ancestor, and because much of the strongest evidence for evolution comes in the form of common ancestry, one must understand phylogenies in order to fully appreciate the overwhelming evidence supporting the theory of evolution.