Science news this week: Life on Mars, weird water and a curious human cousin

This week, we've taken one tantalizing step closer to finding out if there really was life on Mars, after NASA's Perseverance rover uncovered the highest concentration of organic molecules on the Red Planet to date.

The data comes from mudstones in Jezero crater, which once hosted a deep lake. Last year, researchers described a piece of rock with patterns resembling those left by microorganisms on Earth as one of the clearest signs yet of past Martian microbes.

Now, scientists have confirmed the widespread presence of complex carbon-based molecules in this area of the crater, which they suggest indicate the presence of fossilized microbes.

Going even further back in history, new observations from the James Webb Space Telescope (JWST) have revealed how early galaxies lived fast and died young, offering a possible preview of our own galaxy's death.

Elsewhere in space, JWST captured the formation of a distant star, 1,280 light-years away in the constellation Orion, while the Euclid space telescope snapped the most detailed photo of the Milky Way ever taken.

The largest (left) and the smallest (right) skulls of Homo naledi found in the Rising Star cave system in South Africa. All specimens of H. naledi have been shown to be female.

Homo naledi surprised scientists once again this week. Found in a South African cave in 2013, the small-brained, two-legged relative to modern humans is thought to have lived around 300,000 years ago. Since its initial discovery, the enigmatic hominin has shocked scientists with a string of baffling revelations. In 2023, researchers found evidence that H. naledi may have used fire in the cave. This early hominin may also have buried its dead. Now, archaeologists have analyzed genetic material in the enamel of nearly two dozen skeletons at the site and found that they are all female.

"The bottom line is this is a weird result from an already weird hominin," Elizabeth Sawchuk, curator of human evolution at the Cleveland Museum of Natural History, who was not involved in the study, told Live Science in an email.

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The remarkably straight Stane Street in southern England was built by the Romans.

The Romans are known for their transport systems that enabled travel and trade across their enormous empire. Many of these centuries-old streets had a reputation for being extremely straight. Nowadays, building straight roads requires advanced surveying using GPS networks and lasers, as well as careful engineering to flatten the terrain. So how did the Romans do it about 2,000 years before these things were invented?

An illustration of a water molecule. New research adds credence to a controversial theory that water actually switches between two chemical structures.

Most of us discount water as the most basic of beverages, but if you look at it at a molecular level, water is actually rather exciting. Think about it: While most liquids are denser in their solid form, water ice floats. That's weird. Water also resists temperature changes better than similar liquids do, and its viscosity decreases under certain pressures.

Some scientists have hypothesized that these weird behaviors come about because water consists of not one, but two liquids ‪—‬ a dense one and a less-dense one that constantly switch places. Now, with the help of AI, we have proof of this weirdness.

People in China's northern megacities have 74 times less fresh water than the average American — so the Chinese government has built the world's largest water diversion project.

People in China's northern megacities have 74 times less fresh water availability than the average American. But China boasts some of the largest rivers in Asia that flow farther south, along with massive water reserves in glaciers in the west. To address this imbalance, the Chinese government has built the world's largest water diversion project, ferrying water from the Yangtze River in the country's center and south over thousands of miles through a complex system of canals, pipes, dams, reservoirs and pumps.

And yet, this is still not enough to satisfy the water needs of the country's thirsty North. Now, China is expanding these routes and planning a third, western route for the project, which will be the most dangerous and ambitious route yet.

Beyond diverting the country's rivers, China is also building the world's largest dam in an earthquake-prone region in Tibet and has invested heavily in creating a permanent "sky river" to help solve the country's water crisis.

If you're looking for things to keep you busy over the weekend, here are some of the best news analyses, crosswords, interviews, opinion pieces and quizzes published this week.

—60 million stars: Euclid space telescope snaps the most detailed photo of the Milky Way ever taken [Skywatching]

A wave of warm water and higher-than-usual sea surfaces (red) stretches across the Pacific, a few days before El Niño was declared.

New satellite imagery shows a wave of warm water stretching across the Pacific Ocean in a dramatic illustration of the newly declared El Niño. The image shows a red wave as it streaks across the equator and piles up around the west coast of South America.

Ocean patterns like this are known as Kelvin waves. They occur when winds in the Pacific Ocean near the equator temporarily reverse and blow from west to east. This enables warm water to gradually build up in the east,preventing cold waters from rising below.

The wave was spotted by NASA's Sentinel-6 Michael Freilich satellite, which measures ocean temperatures through radar scans of changes in sea surface height, caused by heat's expansionary effects upon water. The satellite has already observed several other Kelvin waves this year in anticipation of El Niño.

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Pandora is the trending news editor at Live Science. She is also a science presenter and previously worked as Senior Science and Health Reporter at Newsweek. Pandora holds a Biological Sciences degree from the University of Oxford, where she specialised in biochemistry and molecular biology.

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