What the scientists are saying…

How to save the planet If we’re going to reduce carbon emissions enough to stop climate change reaching dangerous levels, using energy-saving light bulbs and drying clothes on a line aren’t going to cut it. Such measures, often promoted in government advice, are worth taking, but to make a real impact we should have fewer children, according to a new study. Failing that, we should sell our cars, avoid long-haul flights and adopt a plant-based diet. The researchers say that in the UK, CO2 emissions are equivalent to seven tons per person per year (low relative to the US, at 16 tons), but that to avoid severe global warming, they must fall to just two tons by 2050. Having analysed dozens of research papers, the team, from Lund University, in Sweden, calculates that ditching the car for a year would save 2.4 tons per person; giving up meat 0.8 tons; and avoiding transatlantic flights 1.6 tons per round trip. By contrast, using a washing line, rather than a tumble dryer, saves just 200kg per year, while switching to low-energy bulbs saves about 100kg.

Coffee linked to longer life People who drink coffee regularly have a lower risk of dying from stroke, diabetes, cancer and heart, respiratory and kidney diseases, according to a new study. It’s not clear if it’s an ingredient in the brew that is boosting people’s health, but the team behind the study said they thought coffee must be having some kind of direct impact. In the long-term cohort study, which involved almost 186,000 people of various ethnicities in America, drinking two or three cups of coffee – caffeinated or otherwise – a day was associated with an 18% reduced risk of dying from any cause over the 16-year research period, compared with people who drank no coffee at all. A separate European study, involving more than 450,000 people, found that coffee drinking was associated with a 12% reduced risk of death in men and, overall, a 7% reduced risk in women – but women who drank coffee seemed to have a higher risk of dying of cancer. Cohort studies cannot establish cause and effect, and though they tried to account for other “lifestyle” factors, the researchers acknowledge it could be that people who drink coffee take better care of their health.

Dementia risk is shrinking Around 800,000 people in Britain are living with dementia – a figure that is likely to top 1.2 million by 2040, say researchers at University College London. However, that rise is mainly due to a growing and ageing population: the risk of getting dementia is actually diminishing, thanks to medical advances and people taking better care of their health. Seven years ago, 14.3 men per 1,000 were being diagnosed with dementia; among women, the rate was 17 per 1,000. Now the rate is 12.3 per 1,000 men, and 14.2 per 1,000 women. Had this decline not occurred, there would be 1.9 million people with dementia by 2040.

Did we evolve to sleep fitfully? We think there is something wrong if we sleep fitfully, or have trouble getting to sleep. But it could be an evolutionary throwback – a pattern our ancestors developed to keep themselves safe at night, reports The Guardian. US researchers used wrist devices to monitor the sleep of 33 members of a hunter-gatherer tribe in northern Tanzania, and found that they slept pretty badly by modern Western standards: they woke often in the night, and the young and the old had different sleep schedules, with the old tending to fall asleep earlier, and wake up earlier. The result of this was that during the night, there was always at least one member of the tribe who was either awake or dozing – and therefore attuned to any threat in the environment. Over a three-week period, there were only 18 minutes when all the participants were fully asleep. The researchers also found that despite their wakefulness, the Hadza tribespeople had no anxiety about insomnia. “A lot of older people go to doctors complaining that they wake up early and can’t get back to sleep,” said Charlie Nunn, a professor of evolutionary anthropology at Duke University, in North Carolina. “But maybe there’s nothing wrong with them. Maybe some of the medial issues we have today could be explained not as disorders, but as a relic of an evolutionary past in which they were beneficial.”