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.
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 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.
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.
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.
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.
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.