It used to be thought that the lungs couldn’t regenerate,” says Dr Charlotte Dean, head of the lung development and disease group at Imperial College London. “But we know now that’s not the case. Broadly speaking, they can repair when you quit smoking.”

Smoking is in effect damaging your lungs, Dean says, and the lungs have a substantial capacity to heal themselves. They have evolved to cope with pollution or getting infected by bacteria or viruses. “Because they’re so vital – you can’t survive without your lungs – they needed to have this capacity,” she says.

Dean says this shouldn’t be used as an excuse to smoke, though; smoking and vaping expose your lungs to more toxic particles than they can cope with. Importantly, everyone is different and some people’s lungs will not be able to regenerate as well as others and so will be much more susceptible to permanent tissue damage from smoking.

“While it’s broadly true that if you stop smoking you can revert to having much better lung health, it doesn’t mean you’re completely out of the woods. You may well have triggered mutations or genetic changes or tissue damage, and those things can affect your overall lung health, meaning that the decline as you age will come quicker or could lead to cancer.”

She would encourage smokers to quit as early as possible as – similarly to how your bones don’t mend as well as you age – your lung tissue gets less effective at repairing itself as you get older. A healthy lifestyle can help. “Exercise is really important,” says Dean. “Just like how when you exercise you keep your muscles healthy, in a way the lungs are the same. You build up the capacity for gas exchange to happen more effectively, to provide oxygen around the body.”

The Guardian

On a spring evening along the banks of the River Thames, thousands of mayflies can be seen engaging in what may be one of the world’s oldest dances. In the fading light, the males make a steep vertical climb, flip over and float back to Earth – wings and tail outstretched in a skydiving posture so as to drop slowly through the sky.

Mayflies are among the world’s oldest winged insects, emerging roughly 300m years ago – long before dinosaurs walked the Earth. Even the Mesopotamian poem the Epic of Gilgamesh, one of the oldest pieces of literature, makes reference to the short-lived mayfly. Over the epochs, the insect’s basic design has changed very little compared with the fossils of their ancestors.

“They have retained these odd characteristics and we can probably assume that they’ve been doing this [dance] for hundreds of millions of years, and yet we don’t really know why,” says Samuel Fabian, a research fellow at the University of Oxford who studies the aerial behaviours of insects.

Now, Fabian and his colleagues at Imperial College London think they finally have an answer. In new research published in the Journal of Experimental Biology, the scientists reconstructed the flight behaviour of the common mayfly, filming large swarms in the London borough of Richmond in 3D and analysing the insects’ flight paths.

In further simulations, the scientists found that male mayflies would stop their pursuit of any target that dropped beneath the horizon

“The problem is that the males have almost no filter,” Fabian says. “You can give them a beach ball – which, as far as I’m concerned, looks quite different from a female mayfly – and males will go right up to that much larger object and try to mate with it.”

Things get even trickier in low-light conditions, as females look almost identical to males even at close range. By staying below the females, males ensure their romantic energy is well spent. This is especially critical because mayflies do not have much time, only living from a few hours to a few days, during which they must pass on their genes.

Acing such reproductive goals is crucial to the species’ long-term survival. There are more than 3,000 mayfly species living in the world’s freshwater creeks, rivers, ponds and lakes. But many of Britain’s 51 species are now in a state of decline – another victim of what scientists call the “insect apocalypse”.

A 2019 global review estimated that 40% of the world’s insects were declining, while another study suggests more than 1 in 10 species could be lost by the end of the century.

From 2015 to 2021, the nonprofit conservation group WildFish carried out a riverfly census of Britain’s chalk streams. These streams are some of the cleanest waterways, fed by cool springs that flow from aquifers through chalk, a form of limestone. The species that live here are often very sensitive to pollution.

The census found that Britain’s chalk streams had lost 41% of their mayfly species on average compared with 1998. “In many lowland catchments, the spectacular hatches that once defined early summer have diminished dramatically, reflecting decades of mounting pressure on freshwater ecosystems,” says Janina Gray, head of science and policy at WildFish. “Pollution, sediment runoff, reduced river flows and rising water temperatures are all eroding the conditions these insects depend on.”

Other research suggests that even modest pollution in many English rivers may be enough to kill up to 80% of mayfly eggs, laid in riverbeds.

For now, Fabian encourages Britons to relish the ancient spectacle while they still can.

“This behaviour is something that pretty much everyone, at certain times of the year, should be able to see,” he says.

“These are quite urban places with lots of traffic, but they’re still hanging on and they’re still doing this dance that they have probably been doing since before Britain was separated from mainland Europe.”

The Guardian

It’s an increasingly popular idea: “boosting” testosterone with diet tweaks – increasing foods rich in zinc and magnesium – hoping to build muscle faster. But the reality is more nuanced.

Testosterone is an androgen hormone that plays a key role in development, particularly in boys during puberty. Its effect on muscle isn’t simply about how much of it you have, but how your body responds to it.

“There are two key factors,” says Prof Leigh Breen, a muscle physiology specialist from the University of Leicester. “The amount of testosterone in your system, and the number of androgen receptors in your muscles.” These act like docking sites, allowing the hormone to exert its effects on muscle mass. The number you have is largely determined by genetics, but how well they work can be influenced by lifestyle factors such as exercise.

For most people, natural variations in testosterone don’t make much difference to muscle mass. “For most of our adult life, natural fluctuations, or changes we see with exercise and diet, are subtle,” Breen says.

Testosterone does have a clear impact at the extremes. The most obvious example is anabolic steroid use. These drugs flood the body with testosterone at levels far beyond what would occur naturally. “The effect on muscle mass is significant,” says Breen. “People have been reported to gain muscle even without training.”

At the other end of the spectrum are medical conditions that drastically reduce testosterone, such as hypogonadism in older men. Severely low levels are associated with muscle loss and weakness, which is why some people are prescribed testosterone replacement therapy (TRT).

But, for most of us, testosterone operates within a relatively narrow range. Building muscle still comes down to the fundamentals: consistent training, adequate nutrition and time.

The Guardian