What the scientists are saying…
No water on Mars after all In 2015 Nasa declared that it had found “unambiguous” evidence for the existence of liquid water on Mars, raising hopes of finding life on the Red Planet. But alas it was wrong. The original announcement came after high-resolution images from the agency’s Mars Reconnaissance Orbiter revealed dark streaks on the planet’s surface, known as recurring slope lineae. With these appearing to vary over time and containing hydrated salts – often a sign of water – scientists assumed they were caused by underground water rising to the surface. But a new analysis, undertaken by the US Geological Survey and other institutions, has concluded that the markings were probably produced by nothing more than sand and dust slipping downhill. The report, published in Nature Geoscience, doesn’t rule out Mars having liquid water on its surface, but suggests this is limited to traces of dissolved moisture from the atmosphere. Such “water-restricted conditions”, the researchers found, “would make it difficult for Earth-like life to exist near the surface”.
The promise of better vision Roughly 600,000 people in the UK are afflicted with age-related macular degeneration (AMD), a leading form of blindness. It affects about one in ten over-65s and, owing to our rapidly ageing population, the NHS estimates that the number of people afflicted could reach 700,000 by 2020. However, rates of new cases could soon start falling. When scientists at the University of WisconsinMadison looked at the incidence of AMD across successive generations in one town, they found that rates are falling fast: for people born between 1901 and 1924, the rate was 8.8%, but in the 1925-45 generation, it was only 3%; and for baby boomers (born between 1946 to 1964), it was only 1%. The researchers speculate that improvements to sanitation and medical care over the past century could be factors in the decline. “We’re excited by this because it’s a good news story, and we don’t get very many of those in research,” says study leader Karen Cruickshanks.
To live longer, get a dog Next time your dog chews your slippers or tears up the furniture, bear this in mind: Fido is probably adding years to your life. In the largest study of its kind, researchers in Sweden tracked 3.4 million over-40s for 12 years, and found that dog owners had a 20% lower risk of early death than non-dog owners (a link that persisted even after factors such as smoking, body mass index and socio-economic status were taken into account). The effect was starkest among people who live alone: here, having a dog was associated with 33% lower mortality. Professor Tove Fall, one of the leaders of the study at Uppsala University, in Sweden, said it was likely that this was largely down to the companionship conferred by dogs mitigating the well-documented negative impact of loneliness on human health. But it’s not just a question of having a dog: you need the right kind. Pedigree dogs originally bred for hunting – terriers, retrievers and the like – seemed to confer the greatest benefits. Possibly people who buy these highly active dogs are themselves quite active; even if they are not, their dogs ensure they become so. Professor Fall also speculates that dogs bring an array of microbes into the home that boosts their owners’ immune systems.
Dolly was not a victim of cloning Dolly – the poster ewe for cloned mammals – did not age prematurely, scientists have found. Born in Edinburgh in 1996, Dolly was the first mammal to be cloned from an adult cell, and there were always fears that as a result of being cloned, she’d have genetic problems that would lead to premature ageing. Aged five, she began to limp, apparently the result of early-onset arthritis – suggesting these fears had been well founded. When she died, aged six, some took this as further confirmation of those fears. Yet the virus that led to Dolly’s death also killed other sheep in her barn, and her cloned “sisters” lived to be nine years old, a pretty good age for sheep. Now a team from Nottingham and Glasgow Universities has re-examined Dolly’s bones, and concluded that the extent of her osteoarthritis was normal for an animal of her age.