Here are some big-if-true scientific claims that made headlines in 2023

Lightning strikes above an erupting volcano

Volcanic eruptions can generate lots of lightning. Those strikes split nitrogen molecules in the air, allowing nitrogen atoms to react with other elements to make compounds that living organisms can use.


From ancient cannibalism to stars made of dark matter, 2023 delivered several scientific claims that could shake up their fields — if they shape up to be true.

Spark of life

Early life on Earth may have gotten a boost from giant volcanic eruptions. A new look at debris from 10 eruptions millions of years ago suggests they contained a lot of nitrate that formed in the atmosphere (SN: 6/3/23, p. 7). The eruptions could have triggered fierce lightning that ripped apart molecular nitrogen, freeing nitrogen atoms to bond with other elements and form molecules useful to life — including nitrate. The same process may have happened billions of years ago, some scientists say, producing ingredients for early life. Scientists will need to account for the different chemical makeup of primordial Earth’s atmosphere to bolster that claim.

Butchered bone

Purported tool marks on a 1.45-million-year-old fossilized leg offer the oldest evidence of cannibalism among humans’ ancient relatives, researchers contend (SN: 8/12/23, p. 10). The marks on the bone, found in Kenya, could have been made by some unidentified hominid using a stone tool to carve muscle away from the shin of another hominid. But a few bone nicks do not cannibal table scraps make, some paleoanthropologists say.

A hominid leg bone on the left and a zoomed in view of the bone's surface showing possible stone-tool markings on the right
A roughly 1.45-million-year-old hominid leg fossil bears what some scientists say are stone-tool incisions, shown in a magnified view (right). The claim that this evidence points to hominids butchering one another is controversial.JENNIFER CLARK

Overgrown galaxies

A handful of galaxies from the very early universe are up to 100 times as massive as expected, data from NASA’s James Webb Space Telescope suggest (SN: 3/25/23, p. 14). The hefty galaxies not only challenge the idea that matter clumped together slowly over the universe’s lifetime, but also hint at some unknown way to fast-track galaxy formation. But the galaxies’ weights and distances must be confirmed with more detailed analyses of their light before astronomers rewrite cosmic history.

A composite shows six images of bright, red, extremely distant galaxies
These images from the James Webb Space Telescope zoom in on six bright, red, extremely distant galaxies that appear to be too massive to exist.I. LABBÉ/SWINBURNE UNIVERSITY OF TECHNOLOGY, CSA, ESA, NASA.  IMAGE PROCESSING: G. BRAMMER/NIELS BOHR INSTITUTE’S COSMIC DAWN CENTER/UNIVERSITY OF COPENHAGEN

Thymus rethink

The thymus may not be inconsequential for adult health after all (SN: 8/26/23, p. 7). This immune system organ between the lungs is most active in childhood and withers with age, so it is often considered expendable in adulthood. In a study of more than 2,000 adults who had chest surgery, however, researchers reported that removing the thymus gland was associated with higher rates of death and of cancer within the next few years. Why thymus removal might be harmful remains unclear.

An illustration of the the chest with the thymus highlighted in orange
The thymus (orange in this illustration) is an immune system organ that sits between the lungs, right in front of and above the heart. This gland might be more important for adult health than previously thought.JANULLA/ISTOCK/GETTY IMAGES PLUS

Dead and buried?

Honoring the dead may not be unique to big-brained hominids like Homo sapiens and Neandertals. Homo naledi, which lived around the same time as early H. sapiens but had an orange-sized brain, intentionally buried bodies in an underground South African cave, a group of researchers claims (SN: 7/1/23, p. 6). Other experts remain unconvinced, though. The supposedly buried bodies, which predate the earliest evidence of H. sapiens and Neandertal burials by 160,000 years, could have fallen through cave shafts or been washed by water into natural depressions in cave floors, skeptics say. 

A reconstruction of a grave including adult Homo naledi bones
A proposed grave including the remains of an adult Homo naledi is shown in this reconstruction.L. Berger et al/ 2023

Rocked to the core

Separate studies both based on earthquake data are shaking up geologists’ concept of Earth’s heart. The solid inner core not only rotates but also appears to switch the direction of rotation relative to the mantle and crust every few decades (SN: 2/25/23, p. 7). The inner core may also have a secret chamber (SN: 4/8/23, p. 17). Other data, however, hint that the inner core reverses every few years or does not rotate at all. And the supposed discovery of the innermost core hinges on a type of seismic wave that bounces around Earth’s interior, becoming weaker and more difficult to detect with every bounce. Thankfully, whatever is going on down there does not seem to endanger life on the surface.

A diagram showing a see-through globe with Earth's core in the center and the location of an earthquake in Alaska on the surface. Blue lines connect the core to the earthquake location.
Powerful earthquakes, such as one that occurred in 2018 in Alaska, can send seismic waves reverberating through Earth’s center (illustrated). Such waves reveal an innermost layer to the inner core, researchers say.DREW WHITEHOUSE, SON PHẠM AND HRVOJE TKALČIĆ

Dark matter stars

The James Webb Space Telescope may have spotted stars made of dark matter — the unidentified stuff that makes up most matter in the cosmos (SN: 8/26/23, p. 8). So-called dark stars are so far hypothetical, but JWST observed three objects giving off the kind of light expected from such stars. If they exist, dark stars could shed new light on star formation and the nature of dark matter. However, the pinpricks of light in JWST’s field of view could also come from normal stars, so astronomers will need more detailed data to tease out the objects’ true nature. 

An image taken by JWST shows a tiny dot of light, indicated with an arrow, amid a section of sky scattered with galaxies.
Three pinpricks of light in James Webb telescope images (one shown with a white arrow) give off the kind of light that dark matter stars — if they exist — are expected to emit.NASA, ESA, CSA, JADES COLLABORATION

Previously the staff writer for physical sciences at Science News, Maria Temming is the assistant managing editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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