Science has now provided an excuse for those of us used to being chided by our dentists for not brushing often enough: blame your cavities on the Industrial Revolution. New research suggests that the dietary changes associated with the Industrial Revolution 150 years ago (and with the invention of agriculture 10,000 years ago) caused an epidemic of tooth decay and gum disease. The culprits are oral bacteria. The human mouth is the native home of a wide variety of microbes, some helpful species and some harmful. Over the course of human history, eating more starch and sugar seems to have tipped the balance in favor of the disease-causing bacteria. Even without ultrasonic toothbrushes and mouthwashes, our ancestors may have had healthier teeth than we do!

The 1960s and early 1970s were characterized by a series of protests as groups that had long felt disempowered sought to make their voices heard. California was the heart of many of these new movements. The protests put into motion by the Civil Rights movement evolved to address social justice issues affecting many groups, including students facing the draft, ordinary people protesting the war, farm workers fighting for better working conditions, Chicanos expressing a new identity, and African Americans who felt that nonviolence as a tactic was no longer working. America's continued involvement in the Vietnam War galvanized many groups. Across the United States, students protested US involvement in the war by resisting the draft. All sorts of people joined in by disrupting "business as usual," marching, and going on strike. One photograph shows a banner declaring "On Strike" hanging over UC Berkeley's Sather Gate; the deserted campus demonstrates widespread support among both faculty and students. Other photographs depict students marching in protest against the war, signing a "Women for Peace" petition, and waving an American flag in an anti-war parade. The Chicano Moratorium Committee protested the war by marching in parades, but they also registered their own social justice agenda: one photograph shows them carrying banners that read, "Our fight is in the barrio, not Vietnam."People also rallied around workers' rights, pushing boundaries and demanding better working conditions. The United Farm Workers (UFW), co-founded and led by Cesar Chavez, used strikes to protest the unfair treatment that California's mainly Mexican field workers received. In one photograph pickets stand at the edge of a Central California grape field and carry placards that say "Huelga," Spanish for "strike." Another photograph shows UFW co-founder Dolores Huerta addressing a group. Groups demanding their rights did not work in isolation; a 1971 letter from Cesar Chavez to the NAACP reflects the support that existed between the two groups, both of which were fighting for equal treatment under the law. The Oakland, California-based Black Nationalist organization, the Black Panther Party, was fighting for social justice on several fronts, in a way that often confused their more moderate supporters. They strongly promoted important and positive social issues such as free clinics, programs to feed children, and drug rehabilitation programs; yet, at the same time, they embraced controversial and at times violent tactics. Although Panthers were involved in violent clashes with police, it is still unclear whether the Panthers initiated these actions or were simply defending themselves against police violence directed at them. Many of the Panther leaders were persuasive and charismatic speakers, and photographs here show many of them in action: Black Panther Minister of Defense Huey Newton and his wife, Gwen; Black Panther Chairman Bobby Seale in jail; members of the Black Panthers at a press conference; Kathleen Cleaver in a prosecutor's office; and Angela Davis in Los Angeles speaking to the press after a Black Panther shootout. When Huey Newton was put on trial in 1968, accused of murdering a police officer, Black Panthers lined up on the second day of trial to show their support. Another image shows a multiracial crowd gathered at a Huey Newton rally in 1969 at San Francisco's Federal Building.

In 1862, Congress passed and President Lincoln signed the Pacific Railroad Bill, which granted public land and funds to build a transcontinental railroad. The Central Pacific Railroad would lay tracks from California heading east, and the Union Pacific Railroad would lay tracks from the Missouri River west. The photograph taken in Placer County, "Grading the Central Pacific Railroad," shows some of the construction. Work on the railroad was physically difficult and at times dangerous, and attracting workers was a challenge. The majority of the Central Pacific's laborers were Chinese. A Chinese worker is shown in the image "Heading (top cut) of East Portal, Tunnel No. 8." Both railroad companies actively recruited Chinese laborers because they were regarded as hard workers and were willing to accept a lower wage than white workers, mostly Irish immigrants. As construction progressed, the Central Pacific and the Union Pacific competed to see which could lay the most track each day. A photograph of a sign near Promontory Park, Utah, commemorates the day that Central Pacific crews laid an unprecedented 10 miles of track. The meeting of the two sets of tracks ? the "gold spike" ceremony ? took place on May 10, 1869. Several photographs and drawings depict this historic moment. Now the country was connected as never before: a journey between San Francisco and New York that previously took up to six months now took only days. The photograph "High Bridge in Loop," from Views from a Trip to California, shows a train passing quickly through a mountain pass. The transcontinental railroad allowed people to travel more, farther, and in pleasant conditions, as reflected in the photograph "Commissary Car, 'Elkhorn Club.'" The photograph "Knights of Pythias at the Santa Fe Railway Station, Anaheim" shows an example of the popularity of trains. Even as the transcontinental railroad brought the new country together, it brought change to the world of Native Americans. The tracks ran through a number of tribal territories, bringing into conflict cultures that held very different views of the land and how it might be used and lived on. The painting The First Train, by Herbert Schuyler, depicts three Indians pointing past their encampment at a train in the far distance. The railroad also brought an increasing number of European Americans west. One consequence of this influx was the depletion of the buffalo herds, a major food source for Plains Indians. European Americans would often shoot buffalo for sport from the train; by 1880, the buffalo were mostly gone and Plains Indians had been gathered onto reservations. Millions of acres of open grassland were being settled by the people moving west. Eventually, much of this land became the farmland that fed a growing nation. The transcontinental railroad opened up the West to the rest of the country, even if they never made the trip themselves. A Currier & Ives hand-colored lithograph depicts a train running along the Truckee River in Northern California. The San Francisco publishing firm of Lawrence & Houseworth hired photographers and published photographic tourist catalogs containing views of the West, which they sold commercially. The railroad took hold in popular culture, as shown by sheet music for the song "New Express Galop [sic]." There was even a railroad board game illustrating "Railroads Between New York and San Francisco, California, with Scenes on the Way."

This list of conceptual understandings regarding evolution are aligned across grade levels to help instructors identify age-appropriate learning goals for their students and understand how concepts taught at one grade level lay the groundwork for more sophisticated concepts later on. The Framework is divided into five strands: History of life; Evidence of evolution; Mechanisms of evolution; Nature of science; and Studying evolution

Extinction is a fact of modern life. Humanity's relentless encroachment on the wilderness has marred the diversity of life with conspicuous gaps where the Tasmanian tiger, the Passenger Pigeon, the Ivory-billed Woodpecker, and countless others used to be. As these extinctions accumulate, the Earth inches closer and closer to its sixth mass extinction. We are all too familiar with the concept of mass extinction - a disaster strikes and sets off a chain of events that result in a massive die-off. But you may not have considered what comes next: what happens to surviving species in the wake of a massive extinction event? Recent research suggests that mass extinctions shake up life on Earth in surprising ways.

In the next few months, college students across the country will be offered the chance to save a life by swabbing cells from the insides of their cheeks and registering as a potential marrow donor with Be The Match The Give A Spit About Cancer campaign, which launched in October, helps college students organize marrow donor registry drives. The cells collected in these drives are used to figure out who might be able to donate marrow or blood stem cells to a patient with a life-threatening disease like leukemia. While ethnicity is irrelevant to most medical procedures, marrow and blood stem cell transplants are an exception to this rule.

This course detials the nature and development of economies from pre-history to the Industrial Revolution. It explains how this was dramatically different from modern economies. Finally it considers what caused the Industrial Revolution, why it was in Europe, and why it was delayed till 1800.

This month, the World Health Organization announced that tuberculosis cases are on the decline for the first time in at least 20 years. We seem finally to be winning what has been a very long battle. Tuberculosis bacteria have been attacking us since modern humans began to migrate out of Africa around 40,000 years ago. If you enjoy classic literature, you'll be familiar with the cough, fever, and weight loss of consumption (the old-fashioned term for tuberculosis), which used to be a near certain death sentence. That changed when the aminoglycoside antibiotic streptomycin was discovered in 1943.

Though we often think of evolution as occurring at a snail's pace, one fish species is highlighting just how quickly evolution occurs in the right circumstances. Between 1947 and 1976, General Electric released more than a million pounds of PCBs into the Hudson River. PCBs can kill fish and seabirds and have been linked to cancer and other serious health problems in humans. PCBs were banned in 1979, but the toxins have remained at high levels in the Hudson because they settle into the sediments on the bottom of the river and don't break down. Now, scientists have discovered that, over the past 60 years, one bottom-feeding fish species, the Atlantic tomcod, has evolved resistance to PCBs.