Mars rover finds possible signs of ancient Red Planet life

These tiny ‘leopard spots’, discovered in a rock on Mars by NASA’s Perseverance rover, could be possible signs of microbes that once lived on the red planet. “On Earth, these types of features in rocks are often associated with the fossilised record of microbes living in the subsurface,” says astrobiologist and Perseverance team member David Flannery. Without returning a rock sample to Earth, it will be difficult to further investigate the spots’ origin. “We have zapped that rock with lasers and X-rays and imaged it literally day and night from just about every angle imaginable,” says the rover’s project scientist Ken Farley. “Scientifically, Perseverance has nothing more to give.”

Did complex life start on Snowball Earth?

More than 500 million years ago, the globe was covered in glaciers and sea ice. This Snowball Earth seems hostile to life, yet it was probably during this time that single-celled organisms first evolved into complex, multicellular creatures. One possible answer to this conundrum: when seawater gets colder, it gets more viscous, so individual cells could have started to stick together to move through it more efficiently in search of food. In experiments with modern single-celled green algae, cells living in viscous gels formed coordinated groups to keep swimming.

Heaviest element yet within reach after major breakthrough

Researchers have demonstrated a new way to make superheavy elements, opening the door to creating the heaviest element ever and adding another row to the periodic table. Scientists used a beam of titanium to make a known superheavy element, livermorium — element 116. If they’re able to make elements 119 and 120, as planned after an equipment upgrade, they will be the first documented from the eighth ‘period’. In this row, scientists expect to find atoms with so-far unseen electron configurations.

Mystery oxygen source discovered on the sea floor — bewildering scientists

Something is pumping out large amounts of oxygen at the bottom of the Pacific Ocean, at depths where a lack of sunlight makes photosynthesis impossible. The find has surprised scientists and the source remains a mystery. The oxygen might be generated by metal-rich mineral deposits, or nodules. To researchers’ surprise, they measured voltages of up to 0.95 volts across the surface of the nodules. It is possible that the nodules catalyse the splitting of water into oxygen and hydrogen, but more experiments are needed.

Dogs might have evolved to read our emotions

Centuries of co-evolution seem to have led to dogs being able to sense our emotional states. When dogs were played the sounds of people crying or humming, they appeared more stressed by the sad sounds than by the neutral one. And they’re not just learning from being around us. Pet pigs — who were also raised alongside people but whose species played a very different role in human societies — seemed to find the humming more upsetting.

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As other researchers have previously suggested, this is the result of artificial selection by humans.

Our last common ancestor

The shared forebearer of all life — known as the last universal common ancestor (LUCA) — lived around 4.2 billion years ago, ate carbon dioxide and hydrogen, and produced acetate that might have fed other life. Researchers inferred information about our great-great-grandblob’s genetics and biology by tracing duplicated, lost and mutated genes back up the family tree. LUCA probably possessed an early immune system, too — hinting that it lived in an established ecosystem full of microbes and pathogens.

First fossil chromosomes discovered in freeze-dried mammoth skin

Scientists have discovered intact chromosomes preserved in the skin of a woolly mammoth (Mammuthus primigenius) that met its end some 50,000 years ago — a feat previously thought to be impossible. The team also revealed the spatial organization of the mammoth’s DNA molecules and the active genes in its skin, including one responsible for giving the animal its fuzzy appearance. The study is the first to report the 3D structure of an ancient genome, says molecular archaeologist Ludovic Orlando.

Stars hint at an unusual black hole lurking in our Galaxy

Images taken by the Hubble Space Telescope point to an elusive intermediate-size black hole in the star cluster ω Centauri. Midsize black holes occupy the no-man’s land between the ‘super massive’ ones thought to lie at the centre of most galaxies and much smaller ones that have about as much mass as a single large star. So far, most candidates have turned out to be neutron stars upon closer inspection.

Huge neutrino detector sees first hints of particles from exploding stars

Japan’s Super-Kamiokande observatory is seeing what might be the first hints of neutrinos from exploding stars. Neutrinos are subatomic particles that can come from various cosmic sources; those from inside supernovas could provide information about potentially new physics occurring under extreme conditions. Although the data from Super-K are still too weak to claim a definitive discovery, researchers hope to eventually prove that neutrinos are so stable that those from ancient supernovas are still around.

Ultra-detailed brain map shows neurons that encode words’ meaning

For the first time, individual brain cells have been seen to respond to the essence of words. Researchers recorded the activity of around 300 neurons each in 10 people who had electrodes implanted in their brains to manage epilepsy. Only a few neurons fired for each word when the participants listened to short sentences. Words that fell into similar categories — actions, food or animals — as well as words that could be associated — such as ‘duck’ and ‘egg’ — triggered similar brain activity. To an extent, the researchers could determine what people were hearing by watching their neurons fire.

Denisovans’ survival secrets revealed

The enigmatic ancient humans known as Denisovans hunted marmots, eagles and even hyenas to thrive high on the Tibetan plateau for well over 100,000 years. “It’s at high altitude. It’s cold. It’s not a nice place to be as a hominin,” says archaeologist Frido Welker, one of the researchers who analysed thousands of animal bone fragments from a cave in northern China.

The Milky Way is ‘less weird’ than we thought

Our Galaxy’s core isn't as densely packed with stars as previously estimated, meaning that the Milky Way is similar to other spiral galaxies with around the same mass. Measuring the Galaxy’s size and shape is tricky — it’s like working out how big a city is while standing on a street corner. Instead of extrapolating from the distribution of stars in our immediate galactic surroundings, scientists measured the locations and distances of almost a quarter of a million massive red giants. These old stars are good markers of visible matter in the Galaxy, and their near-infrared light can pass through the interstellar dust that obscures other wavelengths.