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An illustration of the steppe mammoths that preceded the woolly mammoth

Ancient DNA retrieved from different mammoth species is illuminating a complex evolutionary picture.Credit: Beth Zaiken/Centre for Palaeogenetics

Mammoth DNA is oldest ever sequenced

Mammoth teeth preserved in eastern Siberian permafrost have produced the oldest DNA on record. The DNA was extracted from tooth specimens that are up to 1.6 million years old. The DNA identifies a new kind of mammoth that gave rise to a later North American species. The research pushes the technology close to its limits. Once an organism dies, its chromosomes shatter into pieces that get shorter over time. Eventually, the DNA strands become so small that — even if they can be extracted — they lose their information content. The mammoth teeth were preserved in the constant cold of permafrost, which slows DNA fragmentation.

Nature | 6 min read

Reference: Nature paper

Three quantum devices linked in a network

Physicists have taken a major step towards a future quantum version of the Internet by linking three quantum devices in a network. Although the network doesn’t yet have the performance needed for practical applications, it demonstrates a key technique that will enable a quantum Internet to connect nodes over long distances. A quantum Internet would enable ultrasecure communications and unlock scientific applications, such as new types of sensors for gravitational waves.

Nature | 6 min read

Reference: arXiv preprint

Vaccine inequality leaves doctors to die in Africa

Rich countries are rolling out vaccine programmes across their populations while unprotected health-care workers in Africa continue to die from COVID-19. Countries in Europe, Asia and the Americas have administered 175 million shots since December, prioritizing health-care staff. Meanwhile, immunizations have yet to begin in sub-Saharan African countries, where several prominent doctors have died from the virus in recent weeks. Uneven vaccine distribution is exacerbating existing health-care inequities. In addition to the moral imperative, closing the gap would bring worldwide benefits through faster economic recovery and by reducing the chance that new variants arise.

Science | 7 min read

Coronavirus research highlights: 1-minute reads

New COVID variants in the United States

Seven newly identified coronavirus variants in the United States share a similar mutation, but the significance of this change is not yet clear. Coronavirus variants emerging in a range of geographical locations seem to share certain mutations — possible evidence that the changes aid transmission.

(Reference: medRxiv preprint)

One man’s COVID therapy drives viral mutations

Antibody treatment for COVID-19 seems to have spurred mutations in SARS-CoV-2 that infected a man with a compromised immune system. The potential for viral evolution means that convalescent plasma should be used cautiously when treating people with compromised immunity, the authors say.

(Reference: Nature paper)

Viral load, not a cough, makes someone more contagious

The amount of SARS-CoV-2 in a person’s body is a major factor in determining whether they are likely to transmit the virus to others, according to a study of nearly 300 infected people and their close contacts. Researchers monitored 282 people who had recently developed mild symptoms of COVID-19 and 753 of their close contacts. Infected people with a relatively high ‘viral load’, a measure of the amount of virus in the body, were much more likely to pass on the virus than were those with a low viral load. They were no more likely to transmit the virus if they had a cough than if they didn’t.

(Reference: Lancet Infectious Diseases paper)

Food workers face some of the highest COVID risk

The death risk for essential workers in some sectors was 20–40% higher than expected during the first 8 months of the COVID-19 pandemic, according to an analysis of death records in California. Compared with a no-pandemic scenario, deaths were 39% higher for food and agriculture workers, 28% higher for transportation and logistics workers and only 11% higher for non-essential workers.

(Reference: medRxiv preprint)

Read more in Nature’s continuously updated selection of key COVID papers and preprints.

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Features & opinion

A global warning system for viruses

The Global Immunological Observatory is a pilot project for a system that would test blood samples from all over the world to track potential pandemics. This serological monitoring system would look for the presence of antibodies to hundreds of viruses, spotting any infections that are on the rise. The first stage involves the half-million plasma samples from across the United States. The full roll-out would cost millions and require blood from donors around the world.

The New York Times | 5 min read

The secret to winning at maths

Po-Shen Loh has coached the US International Mathematical Olympiad team to the number-one ranking in the world four times in the last six years. Innovations behind his success in the secondary-school-level competition have included inviting rival international teams to the squad’s training camp, taking improvisation classes to improve his own mathematical skills and reaching out to kids from all backgrounds. Puzzle-loving Loh, who also studies extremal combinatorics (objects such as very large graphs or networks), says his goal as a coach isn’t to win, but to maximize the number of team members he reads about in the newspaper in 20 years.

Quanta | 9 min read

Quote of the day

“When HLP countries presented their commitments, Nature emphasized the need to develop accountability measures. No one expected that such mechanisms would be needed within weeks.”

Oil licences undermine Norway’s ocean leadership, write 2 of the 250 scientists who supported 14 heads of state in crafting the High Level Panel for a Sustainable Ocean Economy (HLP), an agreement for 100% sustainable ocean management by 2025. (Nature correspondence | 2 min read)