Reviews & Analysis

The discovery of a rib fragment from Baishiya Karst Cave greatly extends the presence of Denisovan hominins on the Tibetan Plateau. In-depth analyses of fossilized animal bones from the same site show that Denisovans made full use of the available animal resources.

Rhombohedral boron nitride films have a unique combination of properties that make them desirable in electronic and optical applications. An innovative method can be used to create particularly promising large-scale single crystals, bringing the films much closer to real-world applications.

Sea sponges were among the first animals to evolve. But, perplexingly, they left few early fossils despite having dense yet porous bodies. The Ediacaran fossil Helicolocellus cantori is interpreted as having been a glass sponge without biomineralized spicules (little spikes made of glass) to support its body.

A molecule called IL-27 is involved in several immune responses. Congenital alterations in the gene encoding a subunit of the IL-27 receptor result in susceptibility to severe infections with the Epstein–Barr virus. However, IL-27 is also required for the proliferation of virus-infected B cells that become cancerous, so deficiency in the receptor might have a protective role against cancers associated with Epstein–Barr virus.

Imaging of all synaptic connections of individual neurons in larval zebrafish across several days and nights indicates that sleep is necessary, but not sufficient, for the sleep-associated loss of synapses. Both the need to sleep accumulated during wake — known as sleep pressure — and the sleep state itself are required for synapse removal.

A newly characterized neural circuit enables the brain to sense and monitor inflammatory responses in the body, and in turn shape the course of the immune reaction. Artificial activation of components of this body–brain circuit in mouse models of inflammation and immune disorders prevented uncontrolled and dysregulated inflammatory reactions.

It has long been known that ice starts melting at temperatures far below its nominal freezing point, but why or how has remained enigmatic. An innovation in atomic force microscopy provides insights into how this process begins in the most abundant form of ice on Earth.

Myelin is a fatty substance that forms an insulating sheath around the axons of neurons. In mice, drugs of abuse induce neuronal-activity-regulated changes in the myelination of neurons in the brain’s reward circuitry that release the neurotransmitter chemical dopamine. This myelin plasticity is required for the learning of reward associations with drugs of abuse, such as morphine.

A laser technique, which has a time resolution of only a few femtoseconds, captures how photoexcited electrons can influence the chirality — or handedness — of neutral molecules. The resulting helical currents could be used to control physical and chemical properties that result from chiral interactions. This technology could have applications in fields ranging from solid-state electronics to drug design.

Contractile forces at the surface of cells of early human embryos bring the cells together. When these forces are absent, the embryo will not develop further. ‘Weak’ cells do not produce these forces and cannot contribute to the embryo. These observations should influence clinical choices during assisted reproductive-technology procedures.

Primates have rich social lives orchestrated by brain circuits that are still poorly understood, partly because they have not been studied under naturalistic conditions. New wireless technology for recording neuronal activity in freely moving monkeys enabled insights into how neurons track natural social interactions, including reciprocity and social support towards a partner.

The genomes of all eight living species of baobab tree (Adansonia sp.) reveal the group’s origin and diversification history. Ecological analyses were incorporated to characterize the baobabs’ past population dynamics and were used to propose protection measures for these iconic species, including the reassessment of their conservation status and the close monitoring of several of Madagascar’s baobab species.

Long-term memories are thought to be represented by the same brain areas as those that encode sensory stimuli, but the mechanisms remain unclear. A study that recorded neural activity from face-selective regions of the macaque brain found that these regions represent familiar faces using a neural code that is distinct from the one for sensory representation.

A genome-wide association study of metabolic biomarkers in 136,000 participants discovered more than 400 independent genomic regions affecting metabolism. The study also highlighted the importance of participant characteristics, such as fasting status, that can substantially affect the genetic associations.

Clarifying how genome duplication and triplication events shaped early vertebrate genomes has presented a challenge in evolutionary biology. The genome of the jawless hagfish provides a missing piece of this puzzle.

By using volunteers to map roads in forests across Borneo, Sumatra and New Guinea, an innovative study shows that existing maps of the Asia-Pacific region are rife with errors. It also reveals that unmapped roads are extremely common — up to seven times more abundant than mapped ones. Such ‘ghost roads’ are promoting illegal logging, mining, wildlife poaching and deforestation in some of the world’s biologically richest ecosystems.

A hallucinogenic compound secreted by toads has served as a springboard for research into the therapeutic benefits of psychedelics. The findings suggest that these compounds exert antidepressant effects in part by binding an under-appreciated target in the brain.

The oscillating electromagnetic fields that carry light can cause electrons to tunnel back and forth through a potential energy barrier. Remarkably, this alternating current can coherently emit measurable light waves — an unexpected process that can be exploited to build an optical microscope that undercuts existing spatial and temporal limitations.

In ordinary materials, electrons move too quickly for their negative electric charges to affect their interactions. But at low temperatures and densities, they can be made to crystallize into an exotic type of electron solid — a phenomenon predicted by Eugene Wigner 90 years ago and only now directly observed.

A study provides insights into how energy flows in the food webs that connect soil- and canopy-dwelling organisms in tropical ecosystems with high biodiversity. When rainforest is converted to plantations, food webs are simplified and restructured, leading to profound changes in tropical-ecosystem functioning.