Is it a rock — or is it garbage? Human detritus remakes geology

Hello Nature readers,
Today we learn about a stem-cell success for a severe autoimmune disease, hear evidence that ‘AI deskilling’ is real and ponder what even is a rock.

Stem cells stave off autoimmune disease

Two people with a potentially fatal autoimmune disease have been in remission for more than 15 years after receiving a stem-cell transplant. The pair have a rare condition called neuromyelitis optica, which can cause vision loss and limb paralysis. The positive results suggest that the experimental treatment warrants a larger clinical trial, say scientists.

Using AI seems to make skills atrophy

Evidence is building that AI tools can ‘deskill’ experts in medicine, computer science and other fields. For example, a study of experienced physicians found that access to an AI system that analyses colonoscopy images seemed to cause the doctors’ performance to drop significantly whenever the system was unavailable. “Just being aware that this phenomenon exists hopefully provokes some self-reflection about which skills people want to maintain and which they’re willing to outsource,” says information scientist Kevin Crowston.

Ancient babies were born to walk on land

Stunning fossils of tetrapods — four-legged, lizard-y creatures — suggest that we don’t know as much as we thought we did about how creatures came to walk on land. “We have for a very long time assumed that these animals were broadly amphibian-like, and that this life cycle would have bridged the gap between life in the water and life on land,” says Jason Pardo, who contributed to the research. But, rather than undergoing a frog-like metamorphosis from a tadpole to a leggy boulevardier, the 300-million-year-old hatchlings already had little legs, and lacked external gills.

Are these rocks — or are they garbage?

The infiltration of human-made materials into every crevice of our planet has changed the answer to the question, ‘what, exactly, is a rock?’, writes John MacDonald, who researches anthropogenic geomaterials. Must they be hard? Must they be above a certain size? And, perhaps more importantly, must they be natural? MacDonald uses the example of a picturesque cliff in a seaside town in England — which was actually formed from the lava-like slag of a long-defunct iron and steel works — to pick apart what geology means in the age of people.

Futures: Wah-ult in the vault

Experts scour the remains of an ancient world in the latest short story for Nature’s Futures series.

Podcast: DNA sheds light on ancient plague

DNA evidence from the teeth of 5,500-year-old hunter-gatherers has shed light on what ancient plague outbreaks might have looked like. Researchers found evidence that the strain of plague-causing bacterium Yersinia pestis responsible for the outbreak also contained a gene from a related bacterium, called Yersinia pseudotuberculosis. This addition might have increased the severity of outbreaks. “What I think is going on is you have the worst of both worlds,” says paleogeneticist and study co-author Ruairidh Macleod. “So that accounts for why we see this particularly high mortality amongst young adults and young children who potentially are more vulnerable.”