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A white sign with a notice of closure is seen pinned on a black fence to the National Zoo

The closure of the US government has shuttered the Smithsonian Institution’s museums and zoo and some of its research facilities. Credit: Anna Moneymaker/Getty

Government shutdown hits US science

As the United States enters the third week of a government shutdown, the administration of US President Donald Trump has cancelled funding for clean-energy research projects and laid off some 1,300 staff members of the Centers for Disease Control and Prevention (although the notices for 700 were quickly rescinded). The activities of some federally funded museums and laboratories have been suspended, along with the processing of grant applications by agencies such as the National Science Foundation. “It feels like getting hit by a car right after you’ve barely survived a train wreck,” said one anonymous agricultural scientist.

Nature | 6 min read

A conference with all-AI authors

Next week will see a first in computer science, with the launch of a scientific conference in which all of the papers — and all of the reviews — have been produced by artificial intelligence (AI) systems. Agents4Science offers “a relatively safe sandbox where we can sort of experiment with different submission processes, different kinds of review processes”, says co-organizer James Zou. The conference draws attention to “the fact that those of us in the AI world need to do a better job at understanding what the strengths and weaknesses are of using systems in this way”, says computer scientist Margaret Mitchell, who studies AI ethics.

Nature | 5 min read

We will know them by their trail of gum

Ancient DNA pulled from chewed-up wads of birch-bark tar reveals more about the lives of the people who munched it. The material was used as an all-purpose adhesive, and many of the blobs we’ve found have tooth marks. Thirty samples from Mesolithic and early Neolithic sites in what is now Scandinavia were analysed for DNA, revealing traces of human oral microbes and the remnants of plants and animals such as wheat and wild boar. Several pieces contained human DNA that was recognizably male or female — with the male-chewed tar used to haft stone tools and the female-chewed tar used to repair pottery, possibly indicating which crafts tended to be done by whom.

Science | 5 min read

Reference: Proceedings of the Royal Society B paper

A sample of chewed tar pictured from four angles.

Birch bark tar is “the world’s oldest synthetic material”, write the authors, with the earliest finds dating back to the Middle Palaeolithic period in Europe. Theis Z.T. Jensen et al./Proc. R. Soc. B. (CC BY 4.0)

Features & opinion

A reproduction revolution

For decades, fertility researchers have been studying in vitro gametogenesis (IVG) — the process of growing egg and sperm cells in the lab. IVG could provide a way to test whether drugs cause mutations in gametes and explore the causes of, and potential treatments for, infertility. Such uses are at least fifteen years away, by some estimates. But some researchers and government bodies are calling for regulations that address problematic aspects of IVG, such as the potential to generate genetically-modified babies, to be drawn up before the dawn of lab-grown gametes arrives.

Nature | 10 min read

Most carbon credits have ‘fatal flaws’

Most carbon offsets, which allow polluters to meet their emissions reductions targets by financing climate projects elsewhere, have “fatal flaws” that stand in the way of urgent progress, argue a group of environmental policy experts. “The complexity and a lack of transparency make it close to impossible for buyers to make informed decisions about the quality of most credits,” they write. “Moreover, many buyers are not incentivized to care.” Instead of credits, the authors suggest that governments fine facilities that don’t meet mandatory emissions-reduction obligations, raising money for programmes that actually work.

Nature | 11 min read

The fight for snow’s survival

To avoid droughts, sinking tundra fields and an overheated planet, we must take action to protect snow, says environmental historian Sverker Sörlin in his new book, Snö. Filled with emotive memories and riveting case studies of the scientists that solved some of snow’s scientific mysteries, Snö is a “thrilling and moving book” writes science journalist Gareth Thompson in his review. With his personal connection to snow made clear, Sörlin offers “a whispering message to anyone wishing to do better for the planet”, Thompson writes.

Nature | 6 min read

Quote of the day

“On some level, I wish I’d been able to spend my life on something not quite so bleak. On the other hand, I have to confess, I haven’t been bored at any point in there.”

Climate-change journalism pioneer Bill McKibben looks back at the start of his career and the publication of his first book The End of Nature, and his optimism about the unstoppable rise of renewable energy in his latest, Here Comes the Sun. (Mother Jones | 19 min read)