Pertussis bacteria colonize the upper airways, causing a severe cough and shortness of breath that can be fatal in babies. The disease seemed to have mostly disappeared from the United States by the late 1970s—in fact, scientists believe, it continued to spread, undiagnosed, among adults—but over the past 2 decades the disease has bounced back with a vengeance, with strong outbreaks among school-aged children in 2010 and last year, when the United States reported 40,000 cases. Many European countries have also seen increases.

Researchers have long suspected that new vaccines might have something to do with it. Until the 1990s, children routinely received a so-called whole-cell vaccine, made from pertussis bacteria, Bordetella pertussis, that were killed by exposure to formalin or other chemicals. These vaccines were known to contain a toxin that can provoke powerful side effects. Most vaccinated infants had fever and severe pain at the injection site, sometimes accompanied by febrile seizures or fainting fits in which the infant turned pale, unresponsive, and "floppy."

During the 1980s, U.S. parents successfully sued manufacturers, alleging that the whole-cell vaccine also caused long-term brain damage. A 1991 Institute of Medicine report concluded that this was unproven, but by then many pertussis vaccine manufacturers had withdrawn from the market, leading Congress to create a federal vaccine injury compensation program for families who could show a strong case for vaccine damage.

Since then, vaccinemakers have introduced newer, "acellular" vaccines that consist of refined pertussis proteins that provide immunity against disease without severe side effects.

Physicians at Kaiser Permanente of Northern California compared the protective effects of these vaccines with the old ones when included in a four-dose series of shots called DTP (for diphtheria-tetanus-pertussis), given to children before the age of 2. They studied children born between 1994 and 1999, years in which Kaiser Permanente gradually introduced the new vaccines. As a result, some children had received only the old-style shots, some only the new ones, and some a mixture of both. Of the 1037 children included in the main part of the study, 138 got pertussis during a massive epidemic in California in 2010 to 2011.

Children who had received only the acellular vaccine were more than 5.6 times more likely to get sick than those who received the old, whole-cell vaccine, the team will report next month in Pediatrics. Those receiving one or more of each type had an intermediate risk.

The results confirm other recent research. In August, a study published in The Journal of the American Medical Association found that acellular vaccine-vaccinated children in Australia were six times more likely to get sick than those receiving the old vaccine. And a study of another California population, published online in March by Clinical Infectious Diseases, showed an eightfold increased risk of illness associated with the new vaccine.

"We're now finding out that the acellular vaccine's doesn't offer protection for as long," says the first author of the new study, pediatrician Nicola Klein. "It does work well in the short term. But there was definitely a tradeoff in phasing out the whole-cell vaccine."

Whole-cell vaccines, still the standard of care in many lower-income countries, provide more lasting immunity in part because they consist of many more antigens—the proteins that trigger the immune system—than acellular vaccines, current versions of which contain three to five antigens, says James Cherry, a pediatrician at the University of California, Los Angeles. There is also some evidence, he adds, that pertussis strains have mutated in response to vaccination campaigns, rendering antibodies less effective.

Pertussis experts have held two international meetings in the past several months to consider what to do about the waning immunity issue. Cherry thinks that we'd be better off with the old vaccine, but he concedes that there's no going back. "It had to go," says pediatrician Scott Halperin of Dalhousie University in Halifax, Canada. "It's a vaccine that would not be accepted in the societies we have in North America and Europe."

"As much pertussis as we're seeing now, we're still seeing in most places pretty good control in the very young," who are at the highest risk of dying form pertussis, Halperin says. "We're seeing lapsed immunity in school-age kids and we have to solve that. But those kids aren't dying."

Instead, most pertussis experts say what's needed is a new generation of vaccines that provide longer-lasting immunity—but that may take at least a decade. "The scientific community back in the 1990s felt that it had pertussis solved," Halperin says. "We're now seeing that we don't have a solution yet."

Other researchers have used indirect methods to study the use of projectiles, such as analyzing impact fractures on ancient stone points or identifying traces left by hafting on the points. Such evidence suggests that early humans created throwing spears as early as 500,000 years ago in Africa. But that kind of evidence leaves room for doubt and is frequently disputed.

Archaeologist Corey O'Driscoll of South East Archaeology in Canberra became interested in the traces left by hurled spears after reading studies of the wounds that medieval weapons inflicted on humans. In preliminary work, European archaeologists had fired reproductions of Upper Paleolithic points made of antler at the carcasses of oxen and deer, then studied the marks that they left on the bones. But many archaeologists remained unconvinced by the findings, seeing little clear difference between projectile marks and cut marks from butchering. O'Driscoll decided to build on these studies for his undergraduate honors thesis.

He and a colleague knapped flint reproductions of spear and arrow points from the Middle Stone Age in Africa and attached them to wooden shafts. With a group of University of Queensland students, he ran 15 experiments, throwing replica spears and firing replica arrows with bows or a calibrated crossbow at lamb and cow carcasses. After boiling the carcasses or burying them for rapid defleshing by microbes and insects, O'Driscoll found 758 wounds on the bones, which he examined microscopically, and compared to 201 cut marks in an experimentally created reference collection of butchered animal bones.

He found "quite a difference between the butchering marks and projectile impact marks," he says. His study revealed six types of distinctive projectile impact wounds, from drag marks to fracture marks and punctures. O'Driscoll also noted that most projectile impact marks were located on vertebrae or rib bones and that 17% percent of the marks overall—and 50% of the punctures—held microscopic bits of embedded stone from the flint points, due to the high velocity of impact. By contrast, none of the butchering marks contained such stone fragments, another key distinction.

These findings prompted O'Driscoll and the University of Queensland's Jessica Thompson to take a new look at three bone specimens from large unidentified mammals—a rib and two vertebrae—from Pinnacle Point Cave in South Africa. Thompson had earlier detected embedded stone fragments in marks on these bones. Using O'Driscoll's diagnostic criteria, the pair identified projectile impact marks on all three bones. Two dated to between 91,000 and 98,000 years ago—making them the oldest direct evidence of the use of projectile weapons, according to a paper presented at the Society for American Archaeology meeting in Honolulu in April. (O'Driscoll's thesis will be published by the Australian Archaeological Association in June.) A third bone dated even earlier, between 153,000 and 174,000 years ago.

"This is great work," says Curtis Marean of Arizona State University, Tempe, noting that the projectile impact marks, "have a clear and recognizable morphology."

Archaeologist Tiina Manne at the University of Queensland also finds the identification of projectile impact marks—at least on the two later bones—highly persuasive. "This strongly suggests that projectile technology at Pinnacle Point was in use by at least 90 to 95,000 years ago," she says. But she's less convinced by the evidence on the oldest bone, noting that only a "single grain" of stone from the projectile point was embedded in the bone.

Despite this reservation, Manne says that these "exciting" findings can help researchers recognize projectile impact marks on bone in many times and places. They have "incredibly wide-ranging applicability and the potential to further our understanding of when this technology was adopted elsewhere."

Do you pull out your iPhone to calculate the tip at the end of every meal? You're not alone—20% of adults struggle with basic math. A quick zap to the brain might be the answer. A study shows that applying gentle electric stimulation to the brain can boost math skills for up to 6 months. But don't go strapping a battery to your head just yet—researchers don't fully understand how it works, and there could be side effects.

Diarrhea Deaths Decoded

Researchers have isolated the four microbes responsible for causing diarrhea, which kills 800,000 kids in the developing world each year. The biggest surprise was the discovery of a parasite called Cryptosporidium as one of the culprits. Compared with the other three microbes, Cryptosporidium is understudied, and scientists are hoping to speed up research into how to protect against it. In the meantime, a vaccine against one of the other major diarrhea-causing microbes, rotavirus, is ready for rollout in India, where scientists are hopeful that it will help save lives.

Rising Numbers May Not Be Enough to Save Tigers and Kiwis

When it comes to threatened animals, increasing their numbers seems like a happy ending. Not quite, researchers say. A population increase is all very well, but if animal populations experience a loss of genetic diversity, they might be doomed anyway. A lack of genetic diversity can leave a species vulnerable to diseases or threats like a change in climate, because they don't have the evolutionary resources that they need to cope. Researchers are calling this discovery a conservation "red flag" and have identified two species clearly at risk from genetic isolation: the Bengal tiger and the little spotted kiwi.

Malfunction Could Mark the End of NASA's Kepler Mission

After 4 years of faithful service, a reaction wheel malfunction may have scuppered the planet-hunting Kepler spacecraft for good. Kepler is one of NASA's most successful missions—it has discovered more than 2700 possible planets and completed its original 3.5-year mission and then some. But this malfunction has left the craft unable to point in a specific direction, a pretty important skill for a planet-hunter. NASA engineers have put the craft in safe mode and are looking for solutions, but it looks like it may soon be lights out for Kepler.

U.S. Supreme Court Upholds Monsanto Soybean Patents, Rejects Blame-the-Bean Defense

Agribusiness giant Monsanto has won a long-running case against an Indiana farmer who refused to pay royalties on unlabeled beans that he'd bought containing Monsanto-patented genes. The U.S. Supreme Court unanimously ruled that the company's patents cover not just genetically engineered seeds distributed by Monsanto itself, but also any seeds in the environment that contain Monsanto's genes.

Over the years, materials researchers have managed to assemble a handful of simple shapes, such as rods, spheres, and tetrapods, by growing materials from the bottom up an atom at a time. But the ability to grow complex shapes on demand has been limited. Now, scientists have discovered a simple set of design rules for controlling how two different materials—basically chalk and glass—assemble together. Turn the knobs of a solution’s pH, temperature, or the amount of CO2 present and you can alter the way the material grows, changing, for example, from a spiral that resembles a stem, to what looks like a leaf, or even a blooming flower. By turning those dials at just the right time, the researchers grew a variety of luscious-looking blooms that resemble tulips, crocuses, and roses. Discovering similar design rules for magnetic, metallic, and electronic materials, the researchers say, may allow them to pattern catalytic materials and electronic devices over entire surfaces—for making things like cheap solar cells—by simply controlling the conditions under which they are grown.

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