How do we know COVID isn't a bioweapon?

It’s a virus that has infected more than 12 million people and caused more than half a million deaths worldwide. If you have listened to US President Donald Trump and several of his colleagues, the leader of Iran, and official sources in China at various points, this threat came not from nature but was intentional. The conspiracy theory that SARS-CoV-2 actually came from a laboratory has gained traction in recent months, with many accounts blaming the pandemic on a leak (or malicious release).

Will Sydney's bushfire smoke pollution have long-term health effects?

Smoke from the bushfires raging near Sydney in Australia has been blanketing the city in recent weeks, reaching a crisis point on Tuesday when air pollution in parts of the city rose to over 10 times the level deemed hazardous. Health authorities are warning the public to be careful. Children have been forced to stay indoors during lunchtime at school, ferries were cancelled and office workers were evacuated from buildings as the smoke triggered fire alarms.

Extraordinary fossils show how mammals rose from the dinosaurs’ ashes

The discovery of thousands of exquisitely preserved plant and animal fossils in Colorado gives an unprecedented look at life after the asteroid crash that wiped out the dinosaurs. We know that an asteroid slammed into what is now Mexico’s Yucatan peninsula about 66 million years ago, killing three-quarters of living organisms, including all dinosaurs except for birds. But the first million-year period after this mass extinction has a notoriously poor fossil record

Climate change may see one in four US steel bridges collapse by 2040

Global warming could contribute to the failure of one in four steel bridges in the US over the next two decades. Bridges in the US and other high-income countries are ageing and deteriorating. Last year, a large portion of an Italian bridge built in the 1960s collapsed, killing more than 40 people. One of the most common problems involves expansion joints. These allow sections of a bridge to swell and shrink in warmer weather without weakening the structure.

Gut microbes help mice overcome their fears by changing brain activity

Mice with a disrupted gut microbiota may be unable to shake off fearful memories – a finding that suggests our gut bacteria may play an important role in the way we learn. Over the past decade, there has been increasing interest in the role bacteria play in keeping us healthy, especially those living in our gut, mouth and on our skin. Emerging research has linked disruption of these bacterial communities to problems in the immune system and even changes in behaviour.

Australia's anti-encryption law is hurting press and personal privacy

Many politicians are calling for anti-encryption laws. Australia has already implemented one, and it is damaging tech firms, user privacy and freedom of speech POLITICIANS around the world are calling for so-called back doors to let them read messages on encrypted chat apps. But the surprising fall-out from Australia’s sweeping new encryption regulations reveals that such breaches of privacy can have unexpected consequences.

Giving koalas faecal transplants could help them adapt to a new diet

Koalas may need faecal transplants to be able to change diet. The finding could be used to help the animals adapt to habitat loss. While working at Western Sydney University, Michaela Blyton noticed something unusual while studying a koala population that had suffered a dramatic drop in numbers. In 2013, their population had grown so large that they had stripped leaves off their preferred food tree, manna gums (Eucalyptus viminalis), to such an extent that trees died.

Cities are using walls of moss to tackle air pollution from traffic

Walls covered in moss are popping up in major cities, along with promises that they can help reduce air pollution – but can a few square metres of plant matter really tackle the smog? Berlin-based firm Green City Solutions believes so. Its moss walls, called CityTrees, are roughly 4 square metres in size. It says they can filter up to 80 per cent of pollution particles out of the air, including the tiny ones linked to respiratory and cardiovascular diseases.

Neanderthals spent a surprising amount of time underwater

Bony growths found in Neanderthals’ ears suggest that aquatic foraging was a big part of their lifestyle. This adds to evidence that Neanderthals adapted to life in several landscapes, including those near water. Erik Trinkaus at Washington University in St Louis, Missouri, and his colleagues investigated the well-preserved ear remains of 77 ancient humans that lived in western Eurasia in the mid-to-late Pleistocene period.

World’s largest parrot was a metre tall and lived 19 million years ago

Palaeontologists working in New Zealand have discovered the first evidence of giant parrots, which they believe lived 19 million years ago. An analysis of two “drumstick” bones, or tibiotarsi, found at a site on the South Island indicate the bird, named Heracles inexpectatus, grew to around one metre tall and weighed seven kilograms. “It’s a new example of the propensity of islands to generate weird and wacky animals,” says Trevor Worthy of Flinders University, Australia.

Macaques really can use logical reasoning to solve puzzles

Macaques can use logical reasoning to think through tasks, a finding that adds to the growing evidence that animals don’t just make choices purely to maximise the reward they get. Greg Jensen at Columbia University, US, and his colleagues tested the way macaques made what are known as transitive inferences. An example of a transitive inference is the understanding that if A comes before B, and B comes before C, then A must come before C.

Gigantic, mysterious radiation leak traced to facility in Russia

The source of a gigantic, mysterious leak of radioactive material that swept across Europe in 2017 has been traced to a Russian nuclear facility, which appears to have been preparing materials for experiments in Italy. The leak released up to 100 times the amount of radiation into the atmosphere that the Fukushima disaster did. Italian scientists were the first to raise the alarm on 2 October, when they noticed a burst of the radioactive ruthenium-106 in the atmosphere.

Tree stumps that should be dead can be kept alive by nearby trees

A tree stump that should have died is being kept alive by neighbouring trees that are funnelling water and nutrients to it through an interconnected root system. The finding adds to a growing understanding that trees and other organisms can work together for the benefit of a forest. Sebastian Leuzinger at the Auckland University of Technology, New Zealand, and a colleague were hiking through a forest track west of Auckland when they noticed a single tree stump with living tissue growing from it
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