Narwhal tusk is unique thanks to its double twist

The narwhal tusk is nature’s sole straight tusk, and scientists know how it gets its left-handed twist. X-ray images of the tusk’s building blocks, the microscopic collagen fibrils, revealed two layers: the outer layer twists to the left and the inner layer, to the right. The opposing twists create an internal tension, allowing the tusk to grow straight and strong. The detail could help scientists learn how tissues integrate such patterns to acquire certain mechanical properties.

Psychedelics ‘embed’ people more in their environs

Scientists have thought psychedelics disorganised brain signals. A new study has disagreed. Analysing brain scans of 62 adults, researchers found psilocybin caused brain activity to align closer with a person’s environment (e.g. listening to music), a state they called embeddedness, which could be why many people feel a sense of being at one with their surroundings. The stronger this alignment, the more the person’s mood improved later, suggesting it is key to psychedelics’ therapeutic benefits.

Diamond stays diamond even at extreme pressure

By crushing diamond samples with shock waves reaching 1 terapascal, about 10 million times the atmospheric pressure, scientists have found that rather than shift into different crystal structures, they stay intact before eventually melting into a metallic liquid. The experiments revealed that as the pressure increased, diamond’s melting point dropped only slightly. The data can help scientists understand the interiors of giant planets like Neptune, and in refining nuclear fusion setups that use diamond components.