What the scientists are saying…

No sex please, we’re American Americans of all ages are having significantly less sex than they were two decades ago, scientists have reported – a finding that echoes recent research into sexual habits in the UK. The study, published in Archives of Sexual Behaviour, was based on data from the annual General Social Survey. This asks people across America a range of questions about their opinions and behaviour, but the researchers focused on just one: “About how often did you have sex during the last 12 months?” From the responses, they concluded that the average adult had sex 53 times in 2014, down from between 60 and 62 times a year in the 1990s. The fall – which was broadly consistent across ages, races, regions and income brackets – is believed to be partly down to the declining proportion of adults in relationships (who tend to have sex more than singletons); but it also seems that those in relationships are having considerably less sex than in the past. (For singletons, by contrast, there has been hardly any falling-off.) Couples may be giving up sex for a number of reasons, the scientists said: increased access to entertainment and social media could be a factor; as could a decline in reported happiness levels in people over the age of 30, and increased use of antidepressants associated with sexual dysfunction.

Mediterranean diet and cancer Women who eat a Mediterranean diet – rich in fruit, vegetables, nuts and whole grain, and low in salt and saturated fat – are less likely to develop one of the most dangerous forms of breast cancer, scientists have found. For the Dutch study, researchers looked at more than 2,000 post-menopausal women with breast cancer, and compared their dietary histories with those of a similar, cancerfree, group. They found that a Mediterranean diet was associated with a 40% reduced risk for one type of breast cancer, known as oestrogen-receptornegative (or Er-negative). It accounts for about a fifth of all cases, and is more lethal than most because it does not respond to hormone treatments. The diet might not be the cause of the risk reduction: women who eat that kind of diet tend to lead healthier lives overall; however, the team said that the reduction in risk was so great, the link warranted further research.

The oldest fossils? Scientists claim to have discovered the oldest physical evidence of life on Earth – microscopic fossils formed between 3.77 billion and 4.28 billion years ago. The tiny tubes and filaments, etched into a rock in Quebec, are thought to be the remnants of iron-metabolising bacteria that lived near underwater hydrothermal vents – cracks that gush hot mineral-rich water into the oceans. If confirmed, the discovery would, at the very least, make them the oldest known fossils – older than the stromatolites found in Greenland last year, which are believed to be 3.7 billion years old. And if they are as much as 4.2 billion years old, it would change our understanding of Earth’s evolution, suggesting it became hospitable to life earlier than previously thought – soon after the oceans formed. However, the findings, published in Nature, are already being contested, with some questioning whether the etchings are even fossils at all.

Baldness linked to shortness Men who lose their hair prematurely don’t only have their baldness to fret about. The largest genetic study into Male Pattern Baldness (MPB) has indicated that it is not an isolated characteristic, but is related to a host of other traits, some negative. It was already established that men with premature hair loss are slightly more likely than others to suffer from heart disease and prostate cancer. The new research, which involved comparing genetic data from 11,000 men with MPB with that from a similar sized control group, confirmed the prostate link, and found other connections, too. The team, from the University of Bonn, identified 63 genetic variants associated with baldness; the other traits these were associated with included small body size, higher bone density, light skin colour, early puberty – and increased risk of some forms of cancer. (The pattern for heart disease was more complicated.) The researchers stressed that the increased cancer risk, while of academic interest, was too small for individuals to worry about.