Mediterranean is just one of many great diets
Michael Marshall’s look at the Mediterranean diet made one key observation I wish he had expanded on. He described how one scientist said different regions of the world may have their own optimum diet. This is what longevity researcher Dan Buettner found in his study of so-called blue zones, where there are high levels of centenarians. One is in Sardinia, in the Mediterranean, but the other zones are far from it (13 January, p 32).
From one side of the planet to the other, blue zone inhabitants share some striking similarities that can be adapted to suit anyone. Their diets are plant-based and moderate, most have a drink in the evening and they move about a lot by gardening, cooking, playing games or exercising. They find ways to reduce stress, find a purpose in life, offer and receive support and, perhaps most importantly, find their tribe. We could learn a lot from them.
It really does take a village to raise a child
As a psychologist and a mother who struggled in the early months of my babies’ lives in the isolation of suburban Australia, I found Tina Knezevic’s article on postnatal anxiety very interesting (6 January, p 40).
While research into the biological causes of this will continue to make progress, I agree that the condition is “a function of biological, psychological and social factors”. Having travelled and worked in lower-income countries, I suspect that this anxiety is less prevalent in more collectivist societies. It has been said that “it takes a village to raise a child”and a new mother in a nuclear family will typically have had little experience with infants before she gives birth to her own.
The huge responsibility of caring for this vulnerable infant, while typically lacking physical and emotional support from other mothers who may also be struggling with isolation, means anxiety is likely to be high. I look forward to cross-cultural studies on this important topic.
Electric cars may hold the solution to grid shortages
You point out that electricity shortages will probably develop during peak periods in areas of North America, in part due to the lack of new transmission lines to connect new sources of renewable power to population centres. There are similar concerns in Australia (6 January, p 13).
However, little has been written about the hidden power of electric vehicles to help. Surprisingly, EV batteries typically have more than four times the energy capacity of the largest home battery systems. Most EV owners only use a small fraction of that capacity each day, other than on the rare occasions when they need to make a long journey. Newer EVs are now able to export power to the home.
Increasing numbers of EV owners could charge their cars using renewable energy or off-peak energy and then use their car to power the house during peak periods. This could substantially reduce demand for new power lines and improve grid reliability.
Reflections on the idea of mirror matter
I was interested to read about some potential consequences should dark matter consist of “mirror matter”. However, if this exists as a mirror duplicate of all particles and the electromagnetic, weak and strong forces, I question why gravity would be the same for mirror matter as for conventional matter, which it would have to be if mirror matter is dark matter (6 January, p 18).
Dark matter is usually postulated as material that interacts normally in terms of mass and gravity, but very weakly in terms of the other forces. A simpler answer would be that it is conventional matter of a form not covered by the standard model of particle physics, rather than a whole mirror copy of everything we already have except gravity.
Is the Anthropocene far older than we thought?
The beginning of a new epoch has often been defined as when, in a continually deposited sequence of sedimentary rock, an assemblage of animals largely disappears, allowing a new assemblage to evolve, usually evidenced by fossils. The implication is that some catastrophic event wiped out much of the older group (30 December 2023, p 15).
Using that definition, the Anthropocene began in Australia some 50,000 years ago with the demise of . Likewise, it started in the Americas some 11,000 or 12,000 years ago and in New Zealand about 700 years ago, in both cases with the wiping out of megafauna and many smaller animals. If, on the other hand, we use the definition of a change in the climate, looking at the previous handful of glacial-interglacial cycles, we should now be having ice accumulating on the highlands of Baffin Island and beginning to spread southwards. In this case, the .
For every silver lining, there is a cloud
Hannah Ritchie highlights the progress made in developing and deploying new energy sources and more efficient machines, but while such headway is welcome, every silver lining has a cloud (30 December 2023, p 34).
Most of the graphs published with the story are of carbon dioxide per person, but what matters is total emissions, as population growth reduces gains made.
When every thousandth of a degree counts
I suggest we start stating global average temperature rises in millikelvin instead of degrees Celsius, in which case we would refer to our strictest global warming target as a 1500 mK rise. This sounds more serious than 1.5掳C, so might persuade far more people to take serious notice of, and act more quickly on, the crisis (Letters, 6 January).
Reverse causation for this covid-19 link?
You report that people with a severe covid-19 infection are more likely to be diagnosed with schizophrenia, suggesting that covid-19 heightens the risk of this condition (13 January, p 16). Alternatively, could people with undiagnosed early schizophrenia be more likely to catch covid-19, perhaps due to some characteristic behaviours?