Letters archive

While I remain in awe of the detective work that has gone into suggesting a Scottish origin for the altar stone at Stonehenge's centre, I remain dumbfounded by the belief that it was human agency that brought it there ( 24 August, p 16 ). Surely a far more believable story is that the stone …

Acquiring objects from abroad, particularly if they have cultural significance, is something humans like to do. Stones, whether gems or edifices, are particularly popular. Might the altar stone have been acquired in the same way? We now know that it must have come from an area of north-east Scotland. Orkney is at the centre of …

The altar stone isn't the only Scottish connection to Stonehenge. Isotopic analysis of pig teeth near Stonehenge found they had been brought from the Orkney islands for feasting.

In engineering, cynicism is a very practical way to approach big challenges. You must assume that anything that can go wrong will go wrong and proceed accordingly. Only after everything that can go wrong has gone wrong and you have cleaned up the mess can you get on with making things go right ( 17 …

I was delighted to find that moderate consumption of caffeine is good for Homo sapiens . It may not be for some other species: I was once told of experiments on the use of waste pulp from coffee berry processing as cattle feed in Mexico in the 1970s. Although this was full of apparently useful …

From 27 July, p 28

In your review of Anil Ananthaswamy's book Why Machines Learn , I was astonished to read his statement that the mathematics behind AI is simple, "the kind one learns in high school or early college". This may be true of a basic model, but not for ChatGPT, Claude and other neural network-based models, which involve …

You report the growing impact of emissions from food production on the climate. The only way to avoid this kind of damage is for every person to limit their meat intake to less than 200 grams per week. This is a fraction of what many people now eat. We do need dietary vitamin B 12 …

The more I learn in New Scientist about the physical, mental and emotional abilities of animals, the more it strikes me that the only thing that makes us distinctly human is our almost limitless capacity for self-delusion ( 3 August, p 32 )

Many possible factors are outlined that might lie behind a seemingly unstoppable rise in poor mental health among young people. Issues around climate change, lockdowns, smartphones and social media are all suggested as possible causes. Greater awareness and openness around mental health could also contribute ( 24 August, p 14 ). Worryingly, there is no …