Octopus-inspired synthetic ‘skin’ changes colour and texture on demand

Hello Nature readers,
Today we discover octopus-inspired artificial ‘skin’, learn that humans were using poison arrows 60,000 years ago and investigate the quest to authenticate a da Vinci drawing using DNA.

Artificial ‘skin’ changes colour on cue

Researchers have created a synthetic ‘skin’ that can change colour and texture on demand. The material can switch from matte to shiny and display a variety of other effects, before reverting back to its initial state. The team used an electron beam to make a ‘landscape’ of bumps on the surface of a polymer that reversibly swells on contact with water. The bumps absorb varying amounts of water, which resulted in a material that could drastically change its appearance when wet. The flow of liquid can be controlled by covering the material with a transparent film.

Poison arrows used 60,000 years ago

Traces of toxic compounds have been found on 60,000-year-old arrowheads, providing the oldest chemical evidence that Palaeolithic hunter-gatherers used poison to bring down prey. Chemical analysis revealed a compound called buphandrine, derived from the poison bulb plant (Boophone disticha), on arrowheads discovered in KwaZulu-Natal, South Africa. The use of poisons “shows advanced planning, strategy and causal reasoning” among hunter-gatherers, says archaeologist Justin Bradfield. It also suggests that they had a complex understanding of the properties of plants, says archaeologist April Nowell.

Mpox evolution is a ‘bag of surprises’

As mpox continues to spark localized outbreaks in Africa and elsewhere, researchers are racing to understand more about the virus that has caused two public-health emergencies in the past three years. In December, a preprint study found that one mpox strain seems to lurk in the testes of infected male mice. And health officials in the United Kingdom reported that a person had been infected with a never-before-seen strain that is a mashup of two other types. “We should not underestimate what it can do if it’s allowed to become firmly entrenched in human populations and continue to adapt,” says infectious-disease physician Boghuma Titanji.

The Da Vinci (DNA) code

Scientists have recovered DNA from Holy Child, a more than 500-year-old artwork that is thought to have been drawn by Leonardo da Vinci. After analysis, the team suggests that the DNA could be da Vinci’s, which hints that the artwork is in fact his, and not one of his students’. Their current findings aren’t definitive proof, but could demonstrate the promise of ‘arteomics’, an emerging technique that uses DNA and other biological traces to authenticate artworks rather than relying on expert opinion. If proven to be reliable, arteomics “doesn’t just open a new window, it opens a whole new world” for authenticating art, says chemist Stefan Simon.

An antacid for the ocean

Last year, scientists conducted a small test of a new, controversial geoengineering technique to combat ocean acidification: pumping the strongly alkaline sodium hydroxide into the water. If kept at a normal pH, the ocean could continue to absorb carbon from the atmosphere, and marine life would be spared the devastated effects of acidification. Early results suggest the method, called ocean alkalinity enhancement, can work, with negligible effects on marine ecosystems. But tackling ocean acidification globally would require the technique to be rolled out on a huge scale, which could have far more unpredictable impacts in the long term, say some researchers.

Don’t define UPFs, define their opposite

Rather than wrangling over an ever-changing definition of ‘ultra-processed foods’ (UPFs), policymakers should draw up a universal definition of ‘non-ultra-processed foods’, argue three health-policy researchers. Using this static definition in health policies will make the regulatory decisions surrounding food products more clear-cut and prevent manufacturers from reformulating their products to avoid being designated as ultra-processed. “Instead of encouraging manufacturers to switch one ingredient for another, we need a definition that will incentivize the production and distribution of non-ultra-processed foods,” the authors write.