Review, News & Views, Perspectives, Hypotheses and Analyses in 2021

Newly discovered fossil evidence has led to a re-evaluation of one of the fundamental transitions in mammalian evolution: the transformation of bones of the lower jaw into those of the middle ear.

For those fortunate enough to have survived a deadly disease, a vital question remains: how long does their hard-earned immunity last? Tracking of antibodies in Ebola survivors reveals a surprising pattern.

A large-scale, high-resolution cell atlas of gene expression and regulation in human embryos enables innovative investigation of development through multi‑organ and multi‑modal analysis.

Immune cells called macrophages have been found to shut down major metabolic pathways during ageing. Restoring metabolism in these cells is sufficient to alleviate age-associated cognitive decline in mice.

A device has been developed that consists of mechanical bits, analogous to the magnetic bits used in computer hard drives. Information encoded in the bits programs the mechanical properties of the device.

Fractional electric charges have been observed at crystal defects in artificial structures resembling materials called topological crystalline insulators. Such fractional charges could have various engineering applications.

Unique biological traits of bats and adaptive evolution associated with flight confer immunotolerance of viral infection that may help to make bats special reservoir hosts for viruses.

Two animal studies show that restricting the dietary intake of branched-chain amino acids can extend lifespan by modulating the mTOR signalling pathway. But more research is needed before this diet should be recommended in people.

A strategy for machine learning has been developed that exploits the fact that data are often collected in different ways with varying levels of accuracy. The approach was used to build a model that predicts a key property of materials.

A link has been found between repetitive stretches of DNA called tandem repeats and autism spectrum disorder. The discovery might inform approaches to studying tandem repeats in a wide range of other human disorders.

In some materials, the absorption of a single photon can trigger a chain reaction that produces a large burst of light. The discovery of these photon avalanches in nanostructures opens the way to imaging and sensing applications.

Debilitating gut pain is common, but the underlying cause is often unclear. It emerges that gut infection triggers localized immune responses that cause normally innocuous foods to be perceived as harmful, leading to persistent pain.

Celestial eruptions known as giant magnetar flares have been seen in our cosmic backyard, but were so bright they blinded observational instruments. The discovery of a more distant flare finally reveals details of these emissions.

Isoprenoid molecules are essential in many disease-causing microorganisms, and intermediates made during their synthesis trigger immune-defence responses by γδ T cells. ‘Immunoantibiotics’ exploit this dual vulnerability.

No cure exists for the lethal premature-ageing condition Hutchinson–Gilford progeria. A gene-editing tool — adenine base editors — offers a way to treat the condition in mice. Could this approach lead to an effective therapy?

Transitions between amorphous forms of solids and liquids are difficult to study. Machine learning has now provided fresh insight into pressure-induced transformations of amorphous silicon, opening the way to studies of other systems.

The explosive growth of artificial intelligence calls for rapidly increasing computing power. Two reported photonic processors could meet these power requirements and revolutionize artificial-intelligence hardware.