The moon is made of moons, new simulations suggest. Instead of a single colossal collision forming Earth’s cosmic companion, researchers propose that a series of medium to large impacts created mini moons that eventually coalesced to form one giant moon.

This mini-moon amalgamation explains why the moon has an Earthlike chemical makeup, the researchers propose January 9 in Nature Geoscience.

“I think this is a real contender in with the other moon-forming scenarios,” says Robin Canup, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who was not involved in the new work. “This out-of-the-box idea isn’t any less probable — and it might be more probable — than the other existing scenarios.”
A collision between Earth and a Mars-sized object called Theia around 4.5 billion years ago is the current leading candidate for how the moon formed. This impact would have been a glancing blow rather than a dead-on collision, with most of the resulting building materials for the moon coming from Theia. But the moon and Earth are compositional dead ringers for one another, casting doubts on a mostly extraterrestrial origin of lunar material and thus the single impact explanation.
Planetary scientist Raluca Rufu of the Weizmann Institute of Science in Rehovot, Israel, and colleagues dusted off a decades-old, largely disregarded hypothesis that the moon instead formed from multiple impacts. In this scenario, the early Earth was hit by a series of objects a hundredth to a tenth of Earth’s mass. Each impact could have created a disk of debris around Earth that assembled into a moonlet, the researchers’ simulations show. Over tens of millions of years, about 20 moonlets could have ultimately combined to form the moon.
Multiple impacts help explain why Earth and the moon are chemically similar. For example, each impact may have hit Earth at a different angle, excavating more earthly material into space than a singular impact would.

The single impact hypothesis has about a 1 to 2 percent chance of yielding the right lunar mix based on the makeup of potential impactors in the solar system. In the researchers’ simulations, the multiple impact scenario is correct tens of percent of the time. Further investigation of the interiors and composition of the Earth and moon, the researchers say, should reveal whether this explanation is correct.

The last time Earth’s thermostat was cranked as high as it is today, sea levels were high enough to completely drown New Orleans (had it existed at the time), new research suggests.

Ocean surface temperatures around 125,000 years ago were comparable to those today, researchers report in the Jan. 20 Science. Previous estimates suggested that this period, the height of the last warm phase in the ongoing ice age, was as much as 2 degrees Celsius warmer.
Climate scientists often use the last interglacial period as a reference point for predicting how rising temperatures will affect sea levels. The new results, the researchers write, will help scientists better predict how Earth’s oceans and climate will respond to modern warming. Warming 125,000 years ago raised sea levels 6 to 9 meters above present-day levels.

The global scale of that warming has been difficult to estimate. Chemical clues inside dozens of seafloor sediment samples collected from around the world provide only regional snapshots of the ancient climate. Combining 104 of these dispersed data points, climate scientist Jeremy Hoffman of Oregon State University in Corvallis and colleagues pieced together a global climate picture.

Average global sea surface temperatures around 125,000 years ago were indistinguishable from the 1995 to 2014 average, the researchers estimate.

The playground ditty “first the worst, second the best” isn’t always true when it comes to dengue fever. Some patients who contract the virus a second time can experience more severe symptoms. A rogue type of antibody may be to blame, researchers report in the Jan. 27 Science. Instead of protecting their host, the antibodies are commandeered by the dengue virus to help it spread, increasing the severity of the disease.

Four closely related viruses cause dengue, a mosquito-transmitted disease marked by fever, muscle pain and other flulike symptoms. When a previously infected person contracts a second type of dengue, leftover antibodies can react with the new virus.
Fewer than 15 percent of people with a second infection develop severe dengue disease. Those who do may produce a different type of antibody, says Taia Wang, an infectious diseases researcher with the Stanford University School of Medicine.

Wang and colleagues found that dengue patients with a dangerously low blood platelet count — a sign of severe dengue disease — had an abundance of these variant antibodies.

Tests in mice supported the connection. “We found that when we transferred the antibodies from patients with severe disease into mice, they triggered platelet loss,” Wang says.

Wang says it’s not known why some people have this alternate antibody. She and her team want to determine that, along with how these antibodies are regulated by the immune system. With further research, they may be able to screen people to identify those more susceptible to severe dengue disease, Wang says.

Anna Durbin, a dengue vaccine researcher at the Johns Hopkins Bloomberg School of Public Health, doesn’t see a strong connection between this type of antibody and the severity of dengue disease. But she says that the research was interesting in how it connected dengue to low platelet count, a condition known as thrombocytopenia.

“There’s a lot of different theories out there about the role of dengue antibodies and thrombocytopenia, and whether or not the virus itself can enter platelets,” Durbin says. “I think this paper may provide more insight into what is the pathogenic mechanism of thrombocytopenia and dengue, and raises some good avenues for further research.”

Fearful, flighty chickens raised for eating can hurt themselves while trying to avoid human handlers. But there may be a simple way to hatch calmer chicks: Shine light on the eggs for at least 12 hours a day.

Researchers at the University of California, Davis bathed eggs daily in light for different time periods during their three-week incubation. When the chickens reached 3 to 6 weeks old, the scientists tested the birds’ fear responses. In one test, 120 chickens were randomly selected from the 1,006-bird sample and placed one by one in a box with a human “predator” sitting visibly nearby. The chickens incubated in light the longest — 12 hours — made an average of 179 distress calls in three minutes, compared with 211 from birds incubated in complete darkness, animal scientists Gregory Archer and Joy Mench report in January in Applied Animal Behaviour Science.

Chickens exposed to lots of light as eggs “would sit in the closest part of the box to me and just chill out,” Archer says. The others spent their time trying to get away. How light has its effect is unclear. On commercial chicken farms, eggs typically sit in warm, dark incubation rooms. The researchers are now testing light’s effects in large, commercial incubators. Using light exposure to raise less-fearful chickens could reduce broken bones during handling at processing plants, Archer says. It might also decrease harmful anxious behaviors, such as feather pecking of nearby chickens.

Babies are born germy, and that’s a good thing. Our microbiomes — the microbes that live on and in us — are gaining cred as tiny but powerful keepers of our health.

As microbes gain scientific stature, some scientists are trying to answer questions about how and when those germs first show up on babies. Birth itself may be an important microbe-delivery event, some researchers suspect. A trip through the birth canal can coat a baby with bacteria from his mother. A C-section, some evidence suggests, might introduce different bacteria, at least right after birth.

That difference forms the basis of the practice of vaginal seeding, which involves wiping vaginal fluids onto a baby born by C-section to introduce microbes the baby would have encountered in a vaginal birth.

Even while some parents are asking for the procedure, there’s dissent in the ranks of research about its benefits. Scientists don’t agree yet on how — or even whether — type of birth affects the microbiome. “It’s murky,” says obstetrician and maternal-fetal medicine specialist Kjersti Aagaard of the Baylor College of Medicine in Houston. Existing studies don’t clearly distinguish the effects of the C-section itself from those of certain diseases or conditions that can make a C-section more likely, such as maternal diabetes or obesity, she says. Other issues, like whether a baby received antibiotics or is breastfed, also muddy the waters. “You are left saying, ‘Wait a minute. Is it the surgery or not the surgery? What’s going on here?’” Aagaard says.

In a search for clarity, Aagaard and her colleagues surveyed the microbiomes of 81 pregnant women. Later on, the researchers added a second group of 82 women, whose microbiomes were assessed at the birth of their children.

Just after birth, babies who had been delivered by C-section had different mouth, nose and skin microbiomes than babies born vaginally. One possible explanation is that these babies are handled differently just after birth, Aagaard says. The microbiomes of the babies’ meconium, or stool, appeared to be similar, regardless of how the babies were born.

But between four and six weeks later, these C-section/vaginal birth differences on the mouth, nose and skin were largely gone, Aagaard says. The microbes living in and on the babies born by C-section and those born vaginally were nearly indistinguishable, the researchers reported online January 23 in Nature Medicine.
Depending on where they lived, the populations of microbes had already taken on distinct identities by about a month after birth, the researchers found. Communities of nose-dwelling microbes were easy to distinguish from those living in the gut, for instance. These regional differences are signs of surprising microbial maturity, Aagaard says. “Postnatal microbiomes start looking like adults a little sooner than we may have appreciated,” she says.

The results raise an interesting question: If the type of birth isn’t one of the main shapers of microbiomes, then how and when do microbes get into babies? It’s possible that microbes from mothers slip into fetuses during pregnancy — a plausible idea, given some earlier results. Genetically tagged bacteria fed to pregnant mice showed up in their fetuses’ guts a day before the predicted due date, a result that suggests the bacteria traveled from mother to fetus. And Aagaard and colleagues have found evidence of microbes in the placenta of human mothers. They are now studying whether microbes, or perhaps pieces of them, move through the placenta from mother to baby. If that turns out to be the case, then babies meet their microbes, for better or worse, well before their birthday.