Wednesday, February 1, 2023
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Scientists decode why mice go bananas when they’re around the fruit

ScientiFix, our weekly feature, offers you a summary of the top global science stories of the week, with links to their sources.

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New Delhi: Why do mice seem afraid around bananas? Researchers from McGill University in Canada claim to have found the answer — bananas smell the same as a pregnant mouse.

According to the team, among the many odours released in the urine of pregnant and lactating mice, is n-pentyl acetate, which is a form of chemical signalling to defend their offspring. 

The odour, researchers found, produced stress in male mice since the presence of this compound serves as a warning sign to males who might be considering attacking the babies, informing them that the female mice will defend their offspring vigorously. 

This threat or possibility of confrontation is what causes an increase in stress hormones among male mice. Researchers also found that proximity to pregnant and lactating female mice even decreased sensitivity to pain among male mice.

Incidentally, the compound n-pentyl acetate is also responsible for the unique smell of bananas.

The smell of banana extract stressed male mice in the lab just as much as the presence of pregnant female mice would, the researchers concluded. 

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Incas drugged children before sacrificial rituals

The Incas – who once inhabited South America – may have used antidepressants, along with cocaine, to calm children who were chosen for ritual sacrifices, according to a new study

An international team of scientists, including those from Peru, Poland, and the US, studied hair and nail samples taken from the remains of Incans to look for the presence of intoxicating chemicals such as cocaine. 

Human sacrifice, typically of children, known as capacocha, was generally conducted in Incan society to celebrate major events like the birth of a royal, or a battle victory.

Toxicological analysis of two individuals killed over 500 years ago in southern Peru, aged six or seven at the time of their death, revealed that during the last weeks of their lives, the Incan children chewed on coca leaves. Researchers also found traces of ayahuasca – a hallucinogenic beverage made from botanical ingredients with its origins in South America – in the samples.

NASA’s Mars rover has a ‘pet rock’ 

For the last four months, NASA’s Perseverance Mars Rover has had an unexpected travelling companion — a rock that has been hitching a ride on the rover’s front wheel.

The rock has clung to Perseverance, throughout its 8.5 kilometre-journey until now, while making periodic appearances on one of the rover’s cameras. 

But this is not the first time a rock has hitched a ride on a Mars rover mission. Some 18 years ago, a “potato-sized” rock found its way into the Spirit rover’s rear right wheel, and had to be dislodged. Even the front right wheel of the Curiosity rover has periodically picked up its own travelling companion. 

While it’s unclear exactly how long these rocks stuck around, they tended to fell off after a few weeks.

This is why it is important to point out that Perseverance rover’s ‘pet rock’ is on its way to setting Mars hitchhiking records.

Genetics behind electric organs in fish

Scientists have presented an explanation for genetic changes that enable electric fish to evolve ‘electric organs’ which help them send and receive signals. 

These ‘electric organs’ help electric fish recognize other electric fish by species, sex and even as individuals. According to the team, the development of electric organs seems to be the result of natural selection.

All fish have duplicate versions of the same gene that produces tiny muscle motors, called sodium channels. In order to evolve electric organs, electric fish turned off one duplicate of the sodium channel gene in muscles and turned it on in other cells. This is how tiny motors that typically make muscles contract were repurposed to generate electric signals.

The short section of this sodium channel gene – about 20 ‘letters’ long – controls whether the gene is expressed in any given cell. Scientists were able to confirm that in electric fish, the control region is either altered or entirely missing. 

This control region is present in most vertebrates, including humans. Examining the genes in this region, in the case of humans, can help identify sodium deficiencies which might lead to diseases.

Math behind discovery of planets

Artificial intelligence (AI) algorithms can now outperform astronomers in sifting through massive amounts of data to find new exploding stars, identify new types of galaxies and detect the mergers of massive stars.

So far, much of this work was carried out by citizen scientists who manually sifted through huge caches of data to flag image discrepancies that could indicate the presence of a cosmic body. 

According to the researchers from University of California, Berkeley, AI also revealed previously unknown connections hidden in the complex mathematics arising from general relativity — in particular, how that theory is applied to finding new planets around other stars.

The team described how an AI algorithm, developed to quickly detect exoplanets when such planetary systems pass in front of a background star and briefly brighten it, revealed that the theories used to explain these observations are incomplete.

In 1936, Albert Einstein himself used his new theory of general relativity to show how the light from a distant star can be bent by the gravity of a foreground star, not only brightening it as seen from Earth, but often splitting it into several points of light or distorting it into a ring, now called an Einstein ring. This is similar to the way a hand lens can focus and intensify light from the sun.

But when the foreground object is a star with a planet, the brightening over time is more complicated. There are often multiple planetary orbits that can explain a given light curve, called degeneracies, equally well. However, existing theories consist of simplified math, not accounting for degeneracy. 

The AI algorithm pointed to a mathematical way to unify the two major kinds of degeneracy in interpreting what telescopes detect during micro lensing, showing that the two “theories” are really special cases of a broader theory that researchers admit is still incomplete.

(Edited by Amrtansh Arora)

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