What the scientists are saying…
Mars’s lakes are “just a mirage”
There was much excitement in 2018 when scientists said they’d found promising signs of liquid water on Mars. The presence of the “lake” in question, deep beneath the planet’s south polar ice cap, was inferred from radar reflections that seemed bright enough to indicate water. Now, however, a study has concluded that the lake was probably just a “dusty mirage”. US researchers created a simulation of the entire surface of Mars to see how it would look if, like the south pole, it were buried beneath 1.4km of ice. They found that bright patches similar to the one detected in 2018 then popped up all over the planet, covering as much as 2% of its surface, and often corresponding with the locations of volcanic plains. “Mars is known to have these terrains all over the planet, so it’s far more likely to have this terrain under the ice than liquid water,” said lead author Cyril Grima. “We aren’t ruling out this water, but it’s lowering by far the likelihood that it’s there.”
Body fat linked to smoking
Women and girls whose grandfathers or great-grandfathers took up smoking young tend to have more body fat, a study has shown. The link was found by researchers analysing data from the University of Bristol’s Children of the 90s project, which enlisted 14,500 pregnant women in 1991 and 1992, and has tracked them and their families ever since. This revealed that at 17, girls whose maternal greatgrandfathers had smoked before the age of 13 had, on average, 5.35kg more body fat than those whose ancestors had started smoking later; at 24, they had 6.1kg more. Girls whose paternal grandfathers smoked young were 3.54kg heavier at 17, and 5.49kg heavier at 24. No effect was observed in male descendants, though an earlier study had found that boys whose fathers had started to smoke young tended to be heavier. If the findings are confirmed, it would suggest that smoking causes changes to the body that can be passed down the generations. The researchers weren’t able to measure the effect of grandmothers and great-grandmothers’ tobacco use because not enough of them smoked; a further limitation of the study was that it relied on people’s memories of their ancestors’ smoking habits.
The toll of antibiotic resistance
Around the world, more than one million people are dying a year from antibioticresistant bacterial infections, a major new study has found – more than either malaria or HIV/Aids. Researchers analysed data on more than 470 million subjects from 204 countries and used statistical modelling to estimate that antimicrobial resistance (AMR) had been the direct cause of 1.27 million deaths in 2019, and that it played a part in a further 3.68 million deaths. By comparison, Aids and malaria were estimated to have caused 860,000 and 640,000 deaths respectively. Deaths directly caused by AMR were highest in sub-Saharan Africa and South Asia (at 24 per 100,000 people), and lowest in highincome countries (6.5 per 100,000). The findings underline “the true scale of antimicrobial resistance worldwide, and are a clear signal that we must act now to combat the threat”, said study co-author Professor Chris Murray, of the University of Washington.
“Forever chemicals” in our rivers
Toxic chemicals of the kind used in non-stick pans, food packaging and fire retardants have been found in the bodies of otters living in English and Welsh rivers. Known as “forever chemicals” because of the time they take to break down, PFAS have been linked to cancer, liver disease and other illnesses, and there has long been concern about their ability to leach out into waterways. To gauge the scale of the problem, researchers at Cardiff University tested 50 otters found dead between 2007 and 2009 – and detected PFAS in every one of their livers. Otters living in rivers near arable farms and wastewater treatment works had the highest levels. It’s not clear what harm the chemicals had done the otters: most had been killed on roads. But Emily O’Rourke, who led the research, said the findings did suggest that our waterways are widely polluted with them. “This is concerning for the otter, but it is also concerning for us,” she said, “because those rivers feed our reservoirs, we drink that water... so we are getting a dose of PFAS through our food chain.”