Author: Roheeni Saxena

The climate is driven by a complicated interaction of factors. While greenhouse gases contribute to warming, other influences produce a cooling that may mask the full effects of greenhouse gases. We knew that aerosolized particulates produce a cooling effect, but it has been difficult to figure out how large this is, given the ongoing warming.

Research presented in Nature Geoscience now tries to put a number on the aerosol effect. Additional work on the same issue shows that recent changes to emissions regulations may have strongly accelerated the warming happening in the Arctic.

Aerosolized particles in the atmosphere scatter light and cool the planet by reflecting some of the Sun’s light back out into space. Additionally, these particulates may act as catalysts for the formation of clouds, allowing water droplets to accumulate around them. Clouds have a mixed impact on the climate, reflecting incoming sunlight while also insulating the planet to a degree. This particular interaction, between aerosols and clouds, remains a source of uncertainty in climate science.

There are at least two distinct ways to think about intelligence. Some people believe that intelligence is a fixed characteristic, something you are born with, like your bone structure or hair color. Others believe that intelligence is more malleable and can be shaped throughout your life. Regardless of whether either of these is true, it seems that the belief itself can change our behavior.

A new study published in the Journal of Experimental Social Psychology found that believing that intelligence is fixed makes people more likely to overestimate their own intelligence and therefore less likely to develop their own intellectual capacity.

The study used a GRE-style test administered to participants, and it found that people who believe intelligence is fixed are more likely to spend time on easy test questions, but they avoided challenging ones. By contrast, people who have a growth mindset regarding intelligence—believing that intelligence can be developed and changed—are more likely to spend their time on the hardest questions. This develops their skills in answering the problems they find the most difficult.

Social science, including behavioral economics, has recently come under fire as failing to generate studies with reproducible results. The Reproducibility Project made waves in August of 2015 when it announced that reproducing social science experiments is very difficult—not because the original studies were difficult, but because published findings often aren’t as strongly backed by the data as the original authors claimed.

A recent issue of Science contains three articles that alternately contest and defend the reproducibility of social sciences. Critics argue that the true reproducibility rate of articles in these fields is much higher than was initially reported; defenders, including some researchers from the Reproducibility Project, say that the reproduciblity rate is truly less than half.

Though the authors don’t all agree with one another, for the most part they do agree on two things. One is that there were at least some issues with the initial report from the Reproducibility Project, which made a big splash in the media at the time. The second is that we'd probably still like to see higher rates of reproducibility.

The 2014-2016 Ebola outbreak in western Africa made the virus a major public health concern. It increased the push to develop an Ebola vaccine, but there’s also interest in developing a therapeutic treatment, which could limit any future outbreaks after they start.

A recent study published in Science shows that antibodies that target part of a protein on the surface of the Ebola virus makes an effective therapy for Ebola infection in mice. This finding is remarkable because researchers obtained the antibodies from a human survivor of an earlier Ebola outbreak.

Glycoproteins exist on the external shell of a virus and are often used by the virus to latch on to host cells. But their location also make them recognizable by the host’s immune system, which manufactures antibodies against them. The Ebola virus has its own distinctive glycoprotein, which is the only known target for a human antibody response.

According to some linguists, language fundamentally affects the way we see and interpret the world around us. This phenomenon is known as the Sapir-Whorf hypothesis, and it was discussed by WNYC’s RadioLab show in their episode “Why Isn’t the Sky Blue.”

One of the ideas in this linguistic theory is that humans find it easier to identify different categories of color (green versus blue) once we’ve learned the words for them. A study published in PNAS shows that distinct regions of the brain are when pre-linguistic (non-speaking) infants are shown different colors. This indicates that color categories develop in the brain before language.

The researchers used near infrared spectroscopy to determine which areas of the infants’ brains were activated when they looked at either green or blue objects. They also showed infants two different shades of the same color. These experiments were repeated with adults to compare the prelinguistic infants’ brain activity to that of people who had mastered language.

Competition is a significant part of social interaction in the workplace, on the sports field, and in recreational settings. How we respond to that competition is often portrayed as saying a lot about our character. Being branded as a sore loser at a company picnic or after a game night among friends can carry over into relationships. Children are encouraged to play sports as a way to teach them to work in teams and get experience with winning and losing.

A new study published in PNAS, however, suggests that winning a competition may end up making us behave dishonestly, adding further nuance to the paradigm of the “good sport” and the “sore loser.” The work indicates that winners were more likely to steal money from peers during subsequent interactions, perhaps due to feelings of entitlement. While previous studies have shown that honesty and dishonesty can influence the odds of winning a competition, this study presents new data suggesting that these influences go both ways.

The work started by having some participants play in an object recall contest against other people. Afterward, the winners were more likely to dishonestly claim money from their peers in a dice-rolling, money-focused task. The same held true for participants who were simply asked to recall a time when they had won a competition with other people.

Most of the mutations associated with autism spectrum disorder affect genes involved in brain development, as you’d expect. But there’s also a link between the immune system and ASD: viral infection during pregnancy may lead to more cases of ASD in children. A new study published in Science links a specific immune signaling molecule known as interleukin-17a to this phenomenon.

Studies of humans show that viral infection during pregnancy is correlated with an increase in ASD in the ensuing children, though this connection is not yet fully understood. A fundamental tenet of epidemiology is that correlation is not causation, which means that the association between viral infection and ASD doesn’t necessarily mean that catching a virus during pregnancy causes ASD in the baby.

Controlled experiments of pregnancy-related exposures can’t ethically be conducted in humans, so the authors of this paper use mouse models instead. In these mice, when pregnant females are infected with a dsRNA sequence that mimics a viral infection, their offspring show behavioral symptoms typical of ASD. In rodents, ASD-like symptoms include a lack of interest in social interaction, stereotyped repetitive behaviors, abnormal communication behaviors, and other social deficits, all of which can be examined using behavioral tests.

An ongoing investigation at the University of Naples in Italy is looking into allegations that some studies of genetically modified crops included data that was manipulated to make it appear that the consumption of GMOs is harmful to mammals. Frederico Infascelli, the researcher who led these studies, claims that the allegations are false, but evidence has surfaced of widespread image manipulation in his work.

Genetically modified crops, more commonly known as genetically modified organisms or GMOs, have been engineered to make plants heartier in challenging environmental conditions, more resistant to pests or disease, or for a better nutritional profile. Studies have found that GMOs can be effective in reducing the use of pesticides, increasing overall crop yield, and in increasing farmer’s profits. Some of the more common GMO crops include rapeseed, corn, cotton, papaya, soybeans, and beets.

In general, most scientists, Including the American Association for the Advancement of Science, concur that GMOs do not present an increased risk to human health relative to non-modified foods, though the growth and consumption of GMOs has been riddled with controversy. Partially in response to public concerns, some countries require foods using GMOs to be labeled as such.

At the turn of the last century, German physician Heinrich Koch identified four critical criteria for determining whether or not a particular microbe causes a disease. The ideas behind them were crucial for advancing medicine and formalizing the germ theory of disease. Over the last century, these postulates have been updated as medicine has advanced.

In what may end up being the most recent of these updates, biologists Allyson Byrd and Julia Segre propose some adjustments to these classic medical postulates intended to bring them in line with analytic techniques based on DNA sequencing and the most current understanding of bacterial communities. Just as the previous updates to Koch’s postulates did, these proposed amendments incorporate cutting-edge scientific knowledge and add nuance to our understanding of the causes of disease.

Koch’s original postulates are that, if a microorganism causes a disease, then:

Citizens of the United States have a higher income than Costa Ricans, and they spend more of it on health care. In spite of this, Costa Rica has a higher life expectancy than the US—a new article published in PNAS attempts to explain why. The analysis focuses on the steep socioeconomic gradient in health that exists in the US, where the poor have considerably worse health outcomes than the wealthy.

The authors, Rosero-Bixby and Dow, argue that while the wealthiest people in the US have a higher life expectancy than anyone in Costa Rica, the poorest residents of the US have a considerably lower life expectancy.

In Costa Rica, the life expectancy is 78.5 years, though the per-capita GDP is quite low at $9,200. In contrast, the US has a GDP of $40,000, and a life expectancy of 77.4 years. Typically, economic development raises the national life expectancy, so it’s unusual that the US does not have a life expectancy commensurate with its income.