What the scientists are saying…

A ray of hope for the planet The threat of climate change may not be quite as grave as predicted, scientists have found. While the world is still heating up, it has not been warming quite as rapidly as computer models forecast, which means – say scientists in the journal Nature Geoscience – that if we act fast to cut global carbon emissions, its most catastrophic effects can still be avoided. At the 2015 UN Paris Climate Change Conference, one of the study’s authors, Professor Michael Grubb, warned that the summit’s goal – of limiting warming to 1.5ºc above pre-industrial levels – was “incompatible with democracy”. But he now thinks that owing to a less rapid than expected rise in global temperatures in the 15 years up to 2014, there is a chance of achieving it. It had been assumed we could only emit another 70 billion tonnes of carbon before reaching crisis point: now it seems we can emit another 240 billion – about 20 years worth of emissions, instead of only three to five. “It’s the difference between being not doable and just doable,” said Professor Grubb.

Spiders are not like Spider-man Does a spider squeeze its thread out, or pull it out? The former would require its body to withstand pressures normally found in a diesel engine – and so scientists have concluded that the latter must be the case. “It is intuitive to think spiders squeeze out silk like toothpaste,” Chris Holland, of Sheffield University, told The Times. But that is “hard”: it would involve “squeezing something a hundred times thicker than honey through a hole the diameter of a human hair”. Indeed, according to his team’s calculations, not just hard, but impossible: previous research on silkworms has revealed that the pressure required would be 100 times greater than that required to splatter the creatures. Instead, he says, spiders pull their thread out with a leg, while silkworms stick their silk onto a surface and then move on. “[Most] spiders are abseilers,” said Dr Holland. “Not like Spider-man firing silk out of his body.”

Teenagers in mental health crisis Fears about a growing mental health crisis among British teenagers have been exacerbated by a new report suggesting that one in four teenage girls is suffering from clinical depression. The governmentfunded study, based on more than 10,000 young people born in 2000-01, found that 24% of 14-year-old girls, and 9% of boys, have symptoms of depression, including feeling inadequate, lonely and unloved, and hating themselves. Researchers from University College London, and Liverpool University, surveyed the children and their parents. They found that about 10% of parents of boys and girls aged three to ten reported that their children suffered from emotional problems. Based on parental observation, among boys, that level remained constant from 11 to 14, whereas among girls, after the age of 12, it rose to 18%. And when, aged 14, the children were asked about their feelings, 24% of girls described themselves as depressed. By contrast, only 9% of boys did – slightly lower than parental estimates. Depression levels were higher among girls from mixed race and white backgrounds (28.6% and 25.2%, respectively) than among those from black African and Bangladeshi families (9.7% and 15.4%). The findings were based on a questionnaire in which children were asked whether any of 13 statements – such as “I felt lonely”, “I cried a lot”, and “I thought I could never be as good as other kids” – had applied to them in the past fortnight.

Scientists identify a fertility gene A gene editing technique has been used to pinpoint a gene that seems to play a vital role in ensuring a successful pregnancy. The technique, Crispr/cas9, was used to remove from 41 human embryos (donated by IVF patients) a gene that activates the release of a protein, Oct4, in the first few days of embryonic development. Without this gene, 80% of embryos failed properly to develop into a blastocyst – a ball of cells that forms after conception – suggesting it is crucial to a viable pregnancy. The research, conducted at the Francis Crick Institute under a licence from the Human Fertilisation and Embryology Authority, was the first to make use of gene editing to shed light on embryonic development, and could lead to better IVF treatments.