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A researcher has gathered a piece of evidence that helps shed light on the evolutionary transition from soft-bodied animals with no well-defined heads to hard-bodied animals that sported heads. The clue comes from one of the oldest fossilized brains ever found-a more than 500 million-year-old specimen of the Cambrian arthropod Odaraia alata found in western Canada.

Where exactly are the words in your head? Scientists have created an interactive map showing which brain areas respond to hearing different words. The map reveals how language is spread throughout the cortex and across both hemispheres, showing groups of words clustered together by meaning. The beautiful interactive model allows us to explore the complex organisation of the enormous dictionaries in our heads.

Off with their heads. Light-averse planarian flatworms, known for their incredible ability to regenerate lost body parts, shy away from light even after they have been decapitated. This suggests they have evolved a second way to respond to light that doesn't involve eyes. Planarian flatworms, which often live in dark, watery environments shielded from direct light, don't have complex eyes like we do. But many do have two lensless, primitive "eyespots" on their heads that can detect the intensity of light.

In just 15 years, the lizards' heads have grown larger-an adaptation that allows them to eat a wider assortment of insects made available by the dam's creation. The find may portend other rapid evolutionary changes across the globe as humans continue to dramatically alter the natural landscape.  

October 16 is World Anesthesia Day, celebrating the 170th anniversary of the first successful demonstration of surgical anesthesia. Prior to then, surgery was really unpleasant, to put it mildly -- surgeons turned to alcohol, narcotics and even smacking their patients on the head to induce unconsciousness. Fortunately, anesthesia now allows tens of thousands patients every day to avoid the pain and memories of their procedures. But how does anesthesia work? This week, Reactions looks at scientists' current understanding of what happens when you go under.

Some tiny clusters of brain cells grown in a lab dish are making big news at this week's Society for Neuroscience meeting in San Diego. Known as "minibrains," these rudimentary networks of cells are small enough to fit on the head of a pin, but already are providing researchers with insights into everything from early brain development to Down syndrome, Alzheimer's and Zika.

Around the world, disease-carrying mosquitoes are advancing at speed, taking viruses such as dengue and Zika, plus a host of lesser-known ills such as chikungunya and St. Louis encephalitis, into new territories from Europe to the Pacific. "The concern is that we have these species spreading everywhere. Today the focus is on Zika but they can carry many different viruses and pathogens," said Anna-Bella Failloux, head of the department that tracks mosquito viruses at France's Institut Pasteur.

This case study explores the controversy surrounding Yellowstone bison (Bison bison) and the relationship between wildlife management and pluralist democracy. In the late 1960s Yellowstone National Park suspended the policy of strictly managing bison by culling in favor of "natural processes" management. This led to dramatic herd growth and to bison exiting the park in winter in search of forage. Montana cattle ranchers reacted angrily for fear that the animals would infect their cattle with brucellosis. Since 2000, several government agencies have administered the Interagency Bison Management Plan, which uses culling to manage the population at around 3,000 head. The resumption of culling has upset environmental groups, while the recently approved expansion of bison habitat beyond park boundaries continues to upset ranchers.  The ongoing political battle between ranchers, environmentalists, Native American tribes and government agencies shows how difficult it can be to balance legislative mandates, ecological values, and conflicting public demands. The case study may be employed in a variety of courses, including American Government, Public Policy, Interest Groups, Environmental Studies and National Parks.

Methane's potency is one reason why environmentalists are so concerned about natural gas leaks. The Porter Ranch disaster in southern California spewed more than 200 million pounds of methane before it was finally plugged in mid-February. But each year, cows in the U.S. burp out 65 times more gas than was released in the now infamous leak. Globally, about a quarter of methane pollution comes from livestock. Hristov and his team study ways to reduce those emissions, so they have gotten very good at quantifying the amount their cows exhale. Prompted by some extra snacks, cow number 2050 ducks her head into a hooded machine that records the amount of methane, hydrogen, and carbon dioxide in her burps. During experiments, the scientists take eight measurements from each cow over several days. In a few months, this gives a snapshot of just how much methane the animals churn out -- and whether particular interventions work to slash that pollution.

Brain-eating amoebas (Naegleria fowleri) are found in warm freshwater pools around the world, feeding on bacteria. If someone swims in one of these pools and gets water up their nose, the amoeba heads for the brain in search of a meal. Once there, it starts to destroy tissue by ingesting cells and releasing proteins that make other cells disintegrate.

Watch the adventures of the inept "Staph Sargent" and his trusty sidekick as they try to infect the world with germs in this animated educational video. But as they plot their evil plan, they are thwarted at every turn by trained PDI Agents (Protect Don't Infect) who thwart their attempts by washing their hands, covering their cough and sneeze and staying home when sick. This wacky video is aimed at kids aged 6-11 but there's plenty of humor that goes right over their head and finds it's target with mom and dad! With worries about the spread of the H1N1 "Swine Flu," this program is perfectly timed for the beginning of school season. The video was produced by the creative team at Omni Productions in Orlando, FL and is part of a very successful campaign by the Orange County Department of Health.

When it comes to charting the tree of life, the most important difference between humans and sharks isn't limbs versus fins or even lungs versus gills. It all comes down to our skeletons. Sharks' skeletons are made of cartilage, placing them along with rays and skates in a group of jawed vertebrates called cartilaginous fish. Humans-along with most other living vertebrates-belong to the same group as bony fish, whose skeletons are made of bone. Scientists knew that these groups diverged more than 420 million years ago, but what the last common ancestor looked like remained a mystery. Now, new discoveries inside the head of a small fossil fish from Siberia may provide some clues.

Concept maps are tools for organizing and representing knowledge. They include concepts, usually enclosed in circles or boxes of some type, and relationships between concepts or propositions, (indicated by a connecting line and linking word) between two concepts. Linking words on the line specify the relationship between the two concepts. Joe Novak defines "concept" as a perceived regularity in events or objects, or records of events or objects, designated by a label. Think of the concept "Dog" in your mind, what do you see? You might see a prototype shape (head, four legs etc) and typical examples (terrier, collie, sheepdog) and even be able to explain it (give a definition) in words. The label for most concepts is a word, although sometimes we use symbols such as + or %. Propositions are statements about some object or event in the universe, either naturally occurring or constructed. Propositions contain two or more concepts connected with other words to form a meaningful statement. Sometimes these are called semantic units,or units of meaning. Figure 1 shows an example of a concept map that describes the structure of concept maps and illustrates the above characteristics.

The dewlaps of Anolis lizards provide a classic example of a complex signaling system whose function and evolution is poorly understood. Dewlaps are flaps of skin beneath the chin that are extended and combined with head and body movements for visual signals and displays. They exhibit extensive morphological variation and are one of two cladistic features uniting anoles, yet little is known regarding their function and evolution.

More than 400 scientists, bioethicists, and historians from 20 countries on 6 continents have gathered this week in Washington, DC, for the Human Gene Editing Summit. The attendees are a veritable who's who of genome editing: Jennifer Doudna of the University of California, Berkeley, Emmanuelle Charpentier of Max Planck Institute for Infection Biology, and Feng Zhang of the Broad Institute of MIT and Harvard-the three discoverers of the CRISPR-Cas9 system's utility in gene editing-plus dozens of other big names in genome science. Cal Tech's David Baltimore along with the heads of the four national societies hosting the meeting (US National Academy of Sciences, US National Academy of Medicine, Chinese Academy of Sciences, and the U.K.'s Royal Society) provided opening remarks on Tuesday (December 1). And as I sat stage right in the NAS auditorium, I noticed the unmistakable rear profile of Harvard Medical School's George Church three rows in front of me. Church was scheduled to speak at a session later that afternoon about the application of CRISPR and other new precision gene editing techniques to the human germline-a hot-button topic since April, when a Chinese group published it had successfully modified the genomes of human embryos, and the National Institutes of Health (NIH) said it would not fund such research. Then in September, the U.S./U.K.-based Hinxton Group, an international consortium of scientists, policy experts, and bioethicists, said it supported the use of genetic editing in human embryos for limited applications in research and medicine.  

This biomarker, called the KRAS-variant, is linked to more cancers than any other known inherited genetic mutation. It is present in 1 out of every 4 people with cancer, and in more than half of people who develop multiple cancers. KRAS-variant carriers tend to get highly aggressive and recurrent breast, ovarian, head and neck, lung and pancreatic cancers.

Although rabies still causes thousands of deaths globally every year, it has essentially been eradicated from most industrialized countries. Part of the success story is due to an unusual project undertaken by the Swiss prompted by a series of large outbreaks in the 1970s: the large-scale vaccination of wild foxes to stop the epidemic. In this directed case study, students use an easily accessible MS Excel-based model to understand key epidemiological parameters of rabies outbreaks in wild foxes. The simple model allows students also to predict what proportion of foxes needs to be vaccinated to eradicate the virus from the population. The case fits into both ecological and microbiological (epidemiological) courses and offers opportunities to explore zoonotic diseases and "One Health" questions. The mathematical basis of the differential equations in the models is explained, although prior knowledge of calculus is not essential. A key learning outcome is the critical understanding of both the power and limitations of simple epidemiological models. This case was written for an online course but could also be used as a face-to-face activity if students have access to computers in class.