Hello Nature readers,
Today we learn that AI ‘teachers’ can pass their biases onto other models, discover that sperm-whale communication is structured similarly to some human languages and recognize the success of China’s ‘Great Green Wall’.

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AI ‘teachers’ can pass biases onto other AIs

Data generated by artificial-intelligence models can contain subliminal signals that ‘teach’ other large language models (LLMs) particular traits and biases. These preferences can be benign — a favourite animal, for example — but can also cause LLMs to encourage violent or unsafe behaviours. The biases were passed on even when researchers asked preferential LLMs to generate answers on a totally unrelated topic, scrubbed the data of clues about the initial trait and used the filtered output to train student models. But such transmission only occurred when the ‘teacher’ and ‘student’ shared the same base LLM.

Nature | 4 min read
Reference: Nature paper

Human evolution sped up after farming

An analysis of DNA evidence from more than 15,000 ancient humans has revealed that human evolution has accelerated over the past 10,000 years. Researchers identified almost 500 gene variants that evolved through natural selection in ancient European and Middle-Eastern people after the dawn of agriculture. Many of those variants are linked to the resistance to diseases, such as tuberculosis. Accelerated evolution could reflect the intensification of lifestyle changes that started in the Neolithic period, such as new foods and pathogens, says population geneticist David Reich.

Nature | 5 min read
Reference: Nature paper

Sperm-whale chatter is akin to humanspeak

The structure of sperm whales’ communications has close parallels with the phonetics of some human languages. The whales (Physeter macro­cephalus) communicate using a series of clicks called codas. The animals can differentiate the sound by changing the click’s length or using rising and falling tones, which researchers found follow patterns that resemble those used in human languages such as Mandarin and Slovenian. “We’re starting to see that these signals are organized in ways we didn’t fully appreciate before,” says behavioural ecologist Mauricio Cantor.

The Guardian | 5 min read
Reference: Proceedings of the Royal Society B paper

The success of the ‘Great Green Wall’

China’s Three-North Shelterbelt Programme, also known as the Great Green Wall of China, is one of the largest national programmes to push back on encroaching deserts. The project involves creating a huge patchwork of forests across northern China to act as a shield against the movement of sand. The effort is proving successful where others have faltered, largely thanks to its evolving strategy and long-term finance plan, writes a group of environmental researchers. Other countries could learn from the Great Green Wall’s promise — and mistakes — when planning future greening projects to replicate China’s success, the authors write.

Nature | 10 min read

Inside Chornobyl, 40 years later

Decades after the world’s largest nuclear disaster at the Chornobyl nuclear power plant in northern Ukraine, the area “feels like the most picturesque nature reserve on Earth”, writes science journalist Matthew Sparkes. But long-lived radioactive contaminants remain. And, following Russian attacks, the site bears new scars: vandalized laboratories, vast minefields and severe damage to the gigantic edifice that shields the reactor’s ruins. Still, the scientists who work there see its potential. “The Chornobyl zone is a unique place for researchers,” says radioecologist Sergii Obrizan. Agricultural radiologist Kateryna Shavanova agrees. “You should understand our experience and use it. You can practise here. We can use it for something good.”

New Scientist | 16 min read

We are deadening the scent of the world

Sandalwood, vanilla, lavender — just the names of these plants bring their unique smells to mind. But they, along with countless others, are threatened by climate change. Another is frankincense, an example of a scent with profound cultural value. “It’s not just a smell, it’s 3,000 years of history that we lose,” says scent preservation researcher Cecilia Bembibre. Meanwhile, “increased pollution, increased ozone, et cetera, actually is causing damage to the peripheral olfactory system and our ability to smell,” says cognitive neuroscientist Rachel Herz.

Smithsonian Magazine | 11 min read