What the scientists are saying…
The threat to the Gulf Stream
The Atlantic current system that underpins the Gulf Stream – and ensures Europe’s mild climate – is weaker now than it has been for 1,000 years, a study has found, and climate change is likely to be the cause. Further weakening of the Atlantic Meridional Overturning Circulation (AMOC), a “conveyor belt” which brings warm water from the Gulf of Mexico to the north Atlantic, could lead to more storms battering the UK, heatwaves across Europe, and rising sea levels on the east coast of the US. The AMOC has been measured directly since 2004; researchers studied sediments and Greenland ice cores to estimate historic patterns. They believe the current has already slowed 15% since 1950, and that if the planet continues to warm, it could be 45% weaker by the end of this century, bringing it dangerously close to a tipping point, where it becomes irrevocably unstable and at risk of collapse. “The consequences of this are so massive that even a 10% chance of triggering a breakdown would be an unacceptable risk,” study co-author Stefan Rahmstorf, of the Potsdam Institute for Climate Impact Research, told The Guardian.
Your cat would betray you
Even their most devoted owners admit that cats are not the most loyal of pets; now a study has proved their treacherous natures. This showed that whereas dogs will avoid a person who behaves negatively towards their owner, cats will happily take a treat from them. The experiment involved 36 cat owners, who were asked to take part in two scenarios (while their cats watched) in which they struggled to open a container, and asked a stranger (an actor) for help. In one scenario, the actor obliged, in the other, she refused. In both, a third, neutral person was present, who did nothing. Then the actor and the neutral person both offered the cat a treat. The results showed that the cats were just as willing to take food from the actor and the neutral person, regardless of how the actor had behaved. “We found no evidence that cats evaluate humans in third-party interaction,” said the Japanese study, in the journal Animal Behaviour and Cognition.
The approaching “spermageddon”
Some people worry that an asteroid will wipe out the human race; others are more concerned about the impact of climate change. But according to a leading epidemiologist, the gravest threat to human survival may be falling sperm counts. In 2017, Prof Shanna Swan, of the Icahn School of Medicine at Mount Sinai in New York, co-authored a study which found that sperm counts in the West had fallen by 59.3% between 1973 and 2011.
In a new book she warns that if that curve is projected forward, it suggests sperm counts will reach zero by 2045. Of course, it is not certain that they will continue to fall at the same rate. Even so, she says, “That’s a little concerning, to say the least.” Between 1964 and 2018 the global fertility rate fell from 5.06 births per woman to 2.4. Now, half the countries in the world have rates below 2.1, the replacement level. There are socioeconomic reasons for that, including the wider availability of contraception. But Swan thinks there are biological ones too. She points to impaired fecundity even among young women, a rise in boys with genital abnormalities, and the earlier appearance of puberty in girls as evidence of wider hormonal changes. These, she told Axios, are probably being caused by “everywhere chemicals”, as well as obesity and smoking; and the result, she writes, is “various degrees of reproductive havoc”.
How lyrebirds gaslight their mates
The lyrebird is nature’s great mimic, able to reproduce the sounds of other birds – as well as human sounds it hears in the forests of Australia, from chainsaws to car alarms. The male is known to use this skill to impress females; now, it seems it also uses it to scare them into submission. Ornithologists from Cornell University discovered that male superb lyrebirds don’t just imitate the noise of one bird, but the sound of an entire “mobbing flock” – the cacophony that birds use to warn of a predator attack. That was surprising in itself; but they also noted that the lyrebirds mainly did this when a seduction routine seemed to be failing, or during copulation itself. The team speculate that the aim is to persuade the female that she is at risk – and is therefore safest with him.