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The 2019 Pride parade in Brighton, UK. Genetic variants associated with same-sex sexual behaviour can’t be used to predict someone’s sexual orientation.Credit: Sam Mellish/In Pictures/Getty

The largest study so far on the genetic basis of sexuality has revealed five spots on the human genome that are linked to same-sex sexual behaviour — but none of the markers is reliable enough to predict someone’s sexuality. Genomes from nearly 500,000 people have confirmed the suspicions of many scientists: although sexual preferences have a genetic component (this study suggests up to 25% of sexual behaviour can be explained by genetics), no single gene has a large effect on sexual behaviours. Despite the size of the study, the authors caution that the findings might not be representative of the whole population — most of the genomes came from the UK Biobank and consumer-genetics company 23andMe, with contributors to those databases generally being older, and of European ancestry.

Nature | 4 min read

Reference: Science paper

With nuclear tensions escalating between India and Pakistan, experts say the risk of a conflict between the two is the greatest it has been since they both tested nuclear weapons in 1998. Heated political rhetoric from both sides, combined with India’s announcement that it might revoke its ‘no first use’ policy with regard to nuclear weapons, has generated a strong reaction in Pakistan. Both countries are now likely to have changed their nuclear weapons’ readiness from ‘peacetime’ to ‘crisis’, which effectively means preparing the components of a nuclear missile for launch. An actual nuclear strike is still highly unlikely.

Nature | 5 min read

A 10-year excavation at a site in Idaho has dug up artefacts that suggest ancient humans reached the western United States more than 16,000 years ago. The finds make the site, Cooper’s Ferry, one of the oldest-known human settlements in North America. It’s the latest in a growing list of archaeological sites that suggest the region’s first inhabitants travelled from Asia along the Pacific Coast more than 16,000 years ago — and not through an inland ‘ice-free corridor’ in central Canada several thousand years later.

Nature | 3 min read

Reference: Science paper

Soft, thread-like robots less than 1 millimetre wide can be directed around the body using a remote magnet that acts on microscopic magnetic particles in the wire. Researchers showed that the devices can glide through twisting passageways simulating blood vessels in a life-sized replica of the human brain.

Nature Research Highlights | 1 min read

Reference: Science Robotics paper

Get more of Nature’s Research Highlights: short picks from the latest papers.

Guided by a magnetic field, a wiry robot wends through a replica of the blood vessels in the human brain. Credit: Kim et al., Sci. Robot. 4, eaax7329 (2019).

FEATURES & OPINION

The right mentors can have a massive impact on your career and the path you take, but working out who those people are can be a daunting task. Carsten Lund Pedersen created the Mentorship Matrix to guide early-career researchers making these important calls — something he wishes he’d had when he was starting out.

Nature Index | 4 min read

A growing number of journals are accepting Registered Reports, whereby study plans and predictions are peer reviewed before the research is even done. But how exactly do you go about it? Anastasia Kiyonaga and Jason Scimeca turned their experience of the process into a handy how-to guide for researchers looking for practical advice on how to handle this new format.

Trends in Neurosciences | 8 min read

In the first half of 2019, scientists sequenced more ancient genomes than in all previous years combined. But this huge growth in genetic insights comes at a price: the partial destruction of the samples from which the DNA is taken. With no checks or balances in place, Keolu Fox warns of a ‘bone rush’ that lacks the safeguards necessary to protect cultural remains in the long term.

Nature Podcast | 26 min listen

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INFOGRAPHIC OF THE WEEK

BOOKS & ARTS

Emelie Jonsson plays Aniara protagonist the Mimarobe.Credit: Magnolia Pictures

Swedish film Aniara is drenched in existential angst, realism and trippy soundtracks. Based on a 1956 epic poem of the same name, it charts a devastating course for passengers aboard a ship fleeing a scorched, uninhabitable Earth, and becomes an exploration of human adaptability, endurance and despair.

Nature | 3 min read

Barbara Kiser’s pick of the top five science books to read this week includes what makes a dictator, a guide to the apocalypse, and demythologizing language.

Nature | 3 min read

IMAGE OF THE WEEK

Credit: Morgan Bennett-Smith, KAUST Reef Ecology Lab

Just like coral, sea anemones can be bleached by excess exposure to heat and light. This anemone in the Red Sea has lost the algae it once hosted — which provided it with oxygen and food — and has become colourless. Bleaching events are becoming more common with the warming climate. This image by Morgan Bennett-Smith won the ‘Human Impact’ category in Ocean Conservancy’s 2019 photo contest.

See more of the most spectacular images of the month, as selected by Nature’s photo team.