Ingredients
this vida

Ribose, a sugar essential for the structure of RNA, can be produced in space by irradiating pieces of cosmic ice with starlight, states an article published in the journal Science. “Ribose is the central molecular subunit of RNA, but its abiotic origin is unknown”, recall the authors, linked to institutions in France, Mexico and Denmark. RNA is essential for life as it exists on Earth, and scientists believe that this molecule may have played a fundamental role in the very origin of the biosphere.

The article continues: “We observed the formation of substantial amounts of ribose and a diversity of structurally related sugars” among organic residues obtained from laboratory-produced ice, analogous to that existing in interstellar space, after the material had been treated with ultraviolet radiation and heated. These results, the authors point out, are consistent with analyzes of the glacial surface of comet 67P/Churyumov–Gerasimenko, carried out by the Philae space probe.

Note released by Science highlights that the organic residue produced by ice irradiation is soluble in water, an important finding for the field of astrobiology.

Humans in
South America

The spread of human beings across South America – the last habitable continent reached by our species – occurred in two distinct phases, says an article published in the magazine Nature. Based on carbon-14 data from more than a thousand archaeological sites, researchers at Stanford University deduced that a first wave of population expansion occurred 14 years ago.

This wave, however, did not generate exponential growth, but rather a series of low-population settlements, a situation that continued for eight thousand years, including a period of four millennia in which the South American population experienced rapid cycles of explosion and collapse, no net growth.

The second wave, with exponential and sustained growth in the human population, began around 5,5 years ago: in the following three thousand years, the number of people on the subcontinent grew three times. The authors speculate that this growth was made possible by an increase in sedentary lifestyle and the advancement of agriculture.

Special
metastasis

The magazine Science last week features a special section on cancer, focusing on metastases. A specific editorial proposes greater coverage, in the public health system, for molecular profile examinations of cancer cells. Report evaluates the hypothesis that tumors produce “exomes”, vesicles carrying molecules that spread throughout the body and can make other organs more prone to cancer. A literature review analyzes studies on genetic differences between primary tumors and their metastases. Other works deal with different aspects of the disease, including resistance to chemotherapy.

Stars
dead

Atoms of an isotope of iron found in the Earth's crust, at the bottom of the sea, indicate that at least one star exploded in our neighborhood 2,2 million years ago, according to work published in the journal Nature.

Researchers from Germany and Portugal created a model of the transport of Iron-60, an isotope produced in supernova explosions, to the Earth's sea crust. They concluded that the distribution and abundance of the material is best explained by the detonation of two stars, 2,3 million and 1,5 million years ago.

The closest star, located 90 parsecs (293 light years) away, would have a mass 9,2 times that of the Sun and the most distant, 100 pasecs (326 light years), would have 8,8 solar masses. “The Local Bubble of hot, diffuse plasma that the Solar System finds itself in originated from 14 to 20 supernovae within a moving group,” the authors write. “Here, we describe calculations of the most likely trajectories and masses of the progenitors of these supernovae, and the time and location of the explosions.”

Understanding
generates attraction

Being able to easily understand how a person feels increases the attraction we feel for them, says a study published in the journal PNAS. “Human beings interacting with other human beings need to be able to understand the motivations and affects of the interaction partner, often without exchanging words,” write the authors, from German institutions.

In carrying out the research, 92 male volunteers were asked to watch video clips depicting women in different displays of emotion. Volunteers had to describe the emotion represented, and what level of confidence they had in the description made. To determine level of attraction, men were asked to zoom in on a photo of each woman to a distance that felt “comfortable” to them. There was a correlation between the degree of confidence in the description of the emotion and the attractiveness index.

In addition, the researchers subjected the volunteers to functional magnetic resonance imaging of the brain, and discovered that high levels of certainty regarding the emotional description and the high attraction index also correlated with the activation of reward areas of the brain.

'Awareness Day'
raise awareness?

The use of commemorative dates – so-called “consciousness days” – to draw the general public's attention to social or health issues has become increasingly common, but research into the actual impact of these celebrations on attitudes and population behavior is still inconclusive.

Now, an article by researchers at San Diego State University (USA), published in the online journal JMIR Public Health and Surveillance, suggests that at least one of these dates – Great American No Tobacco Day, celebrated in the United States on the third Thursday of November – has a notable effect, at least in the virtual world.

The authors have been monitoring the media and online activity of Americans on this date since 2009, and detected a significant increase in searches for information about how to quit smoking on Google and Wikipedia, as well as a greater spread of motivational messages about it on Twitter. during the Big Day, compared to normal dates.

“Compared to what would be expected on a normal day, Great American No Tobacco Day typically coincides with a 61% increase in news about quitting smoking and a 13% increase in tweets encouraging people to stop the habit,” says a statement released. by the University.

Uncertainties about
the future of water

European researchers have reconstructed the relationships between climate and water availability in the Northern Hemisphere over the past 1.200 years, using nearly two hundred databases on rainfall, drought, marine sediments, tree growth rings, ice cores and other indicators. Published in the magazine Nature, the study diverges, in its results, from the predictions about the relationship between water and climate made in climate models for the 20th century.

Models that take into account climate change caused by excess CO2 in the atmosphere predict a radicalization of hydrological conditions, with increasingly intense rains and droughts, but the reconstruction does not support this conclusion. “We compared the reconstructed hydroclimate anomalies with model simulations of the coupled circulation of the atmosphere and ocean, and found a reasonable agreement for the pre-industrial period”, says the text. “However, the intensification of average hydroclimatic anomalies in the 20th century” highlighted by current simulations “is not supported by our reconstruction”.

In a comment accompanying the European article, American researcher Matthew Kirby, from the University of California, draws attention to the uncertainties that still surround models of the relationship between climate and water availability. “There is no doubt that global warming will change the Earth's water cycle,” he writes. “The more we know about the behavior of the cycle in the past (...) the more confidence we will have in the predictive models”.

Transplant
between species

The controversial field of xenotransplants – which researches the feasibility of using animal organs from one species in another – has broken a new record, reports an article in the journal Nature Communications.: A pig heart attached to a baboon's body remained alive for more than two years, thanks to a new immunosuppressive therapy. Xenotransplants are studied as an option for the shortage of human organs for transplantation. 

In the described experiment, the pig's heart did not replace the primate's, but was merely connected to its circulatory system. The pigs used had been genetically modified to obtain a high degree of immunological tolerance in the baboons. In total, five primates received “extra” pig hearts, and the transplanted organs survived for the duration of immune modulation therapy.