ESA lands probe on comet

The Philae robot, from the European Space Agency (ESA), performed a historic feat by landing safely on the surface of comet 67P/Churyumov–Gerasimenko on the afternoon of last Wednesday, 12. This is the first time that an instrument built by humans lands gently on a comet: in 2005, the NASA Deep Impact probe fired a projectile at comet Tempel 1, to analyze the composition of the debris expelled by the shock. 

To get a hold on 67P, Philae should have fired a harpoon, which didn't work. With that, the robot bounced off the comet, before stabilizing itself. Philae was transported to the comet's neighborhood by the Rosetta probe, launched more than ten years ago. The joint Rosetta-Philae mission aims to carry out the most complete studies of a comet ever carried out.

The threat of the Western diet

The reduction of poverty and the growing urbanization of the world are producing a dangerous and undesirable side effect, says an article published in the magazine Nature: the universalization of the “Western diet”, based on refined sugar, processed fat and the consumption of large quantities of meat and oils. According to the authors, linked to institutions in the United States, this universalization threatens not only human health, but also the environment.

“By 2050, these trends (...) will be an important contribution to the estimated 80% increase in greenhouse gas emissions from agriculture”, says the article. “In addition, these dietary changes are increasing the incidence of type 2 diabetes, coronary heart disease and other non-contagious chronic diseases that reduce overall life expectancy.” The work compares several studies carried out on the impacts on health and the environment of diets such as vegetarian, Mediterranean and the so-called omnivorous diet. 

The study reminds us that a transition between types of diet is a complex phenomenon – influenced by culture, price, availability, personal taste – and that the search for a solution to the “diet-environment-health trilemma is a global challenge and an opportunity to big importance".

A solar system is born

Image produced by the ALMA observatory, a set of dozens of antennas mounted in the Atacama Desert, in Chile, shows, with unprecedented clarity, the stage of planet formation from a primordial disk of cosmic dust. 

The disk captured by ALMA revolves around the star HL Tauri, located about 450 light-years from Earth. It is a young star, less than a million years old – the Sun, in comparison, is more than 4 billion years old – and gaps can already be seen in its dust disk that indicate the segregation of primitive material into the bands that should give rise to the orbits of the planets.

“The disk already appears to be full of planets in formation,” said researcher Catherine Vlahakis, one of ALMA’s leaders, in a note. The stage of planet formation in HL Tauri's disk appears to be much more advanced than current theories predict. “This image will revolutionize theories of planet formation”, believes the researcher.

Swamps in lakes

Deforestation in humid areas, such as swamps, marshes and mangroves, tends to increase the availability of water in these areas, says an article published in the magazine Science. According to the authors, the phenomenon can lead to the transformation of swamps into lakes and even the emergence of new swamps.

“After complete deforestation, we demonstrate that the water available to humid areas increases by up to 15% of annual precipitation”, write the authors, linked to Australian institutions. They state that this is an impact rarely evaluated in studies on the effects of human intervention on the environment. “Studies should be done to determine fundamental hydrological conditions in deforested wetlands, not just sedimentation rate and trophic status,” they write. “From a management point of view, reforestation of wetlands can radically alter the water balance and, in some cases, the protected wetland may disappear.”

Mosquito preference

The dengue mosquito, which evolved to specialize in biting humans, differs from its relative, which prefers other types of animals, and which still exists today on the coast of Africa, due to an olfactory receptor, AaegOr4, which, according to the authors of the article, published in Nature “recognizes a component present at high levels in human odor”. “Our result offers a rare example of a gene contributing to behavioral evolution,” the researchers write.

The substance detected by this receptor is sulcatone, “a volatile odorant repeatedly associated with human body odor,” says the article. “Although sulcatone is also emitted by a number of other animals and plants, it appears to reach exceptionally high levels in humans.”

Feline genetics

The journal PNAS brings the first large-scale comparison of the genomes of domestic cats and wild cats, highlighting the main differences between the two groups. Cats have lived with humans for around 9.000 years, but the first breeds of cats created by artificial selection only emerged less than 200 years ago, in a process of aesthetic selection, and not, as in the case of other domesticated animals, functional.

The work, carried out by an international team of researchers, shows that domestic cats appear to have undergone selection that favored genes linked to memory, fear conditioning of behavior and learning through stimulation and reward. 

Rapid extinction

A small human population was enough to drive the moa, a type of New Zealand bird similar to the emu, to extinction, says a study published in the journal Nature Communications. According to the authors, the extinction of the moa was caused, over the course of approximately one hundred years, by “one of the lowest population densities ever recorded”, of a maximum of 2.500 individuals.

Moa were hunted to extinction by Polynesian settlers who arrived on the South Island of New Zealand around the year 1300 AD. Around 80 years later, the bird had already disappeared from the most accessible areas of the island. The species would disappear for good around 1425.

The authors draw attention to the argument that hunting by humans could not have led to the extinction of species such as the mammoth or the giant sloth, because the human populations involved would be too small, and state that their conclusions show that this line of reasoning does not is more sustainable.

GMO potato for frying

The United States Department of Agriculture has approved the commercial production of a transgenic potato variety created to produce smaller amounts of the molecule acrylamide, suspected of being a carcinogen. In addition to this characteristic, the potato, developed by the company JR Simplot, an important supplier of fast-food chains such as McDonald's, is less injured during transportation and harvesting. 

Upon reporting the approval, the newspaper The New York Times highlights that potatoes represent a “new wave of genetically modified products”, which promises benefits for the end consumer and not just for the farmer. The newspaper recalls, however, that other attempts to introduce transgenic potatoes into the North American fast-food market failed, due to fear of public resistance.

Wikipedia analysis predicts epidemics

More and more people search for information about diseases on the internet before seeking or obtaining medical care, which means that an analysis of Wikipedia access statistics can detect an epidemic before it is registered by health authorities, says an article published in the journal PLoS Computational Biology.

The authors, linked to the United States government's Los Alamos National Laboratory, used mathematical models to analyze access records to the online encyclopedia and were able to predict, up to 28 days in advance, and monitor the evolution of epidemics in eight of 14 situations analyzed, including dengue outbreaks in Brazil.

The authors acknowledge that the model presented is still embryonic and that there are sources of noise in the information that need to be overcome, but write that “this article establishes the utility of Wikipedia as a broadly effective data source for disease information.”

'BioRxiv' turns one year old

The repository of scientific articles in pre-publication in the area of ​​biological sciences, the BioRxiv, maintained by the Cold Spring Harbor Laboratory, in the United States, completed a year with more than 800 papers available. O BioRxiv follows in the same spirit as the oldest ArXiv, from Cornell University, dedicated to exact sciences: it is a place where scientists can publicly disclose their work before submitting it to a scientific journal, receiving criticism and suggestions from colleagues. Throughout this year, the ArXiv received more than 7.000 articles per month.

The creators of BioRxiv say that the fear that an article released in the repository will end up “burned” for publication in a high-impact journal is not justified: last year, they told Science Insider, online magazine news service Science, that 95 journals accepted articles initially published in BioRxiv, including Nature, Nature Neuroscience e Science.