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Veganism isn't about human health, it is about animal health: if you don't breed, enslave, slaughter, skin and eat animals, they tend to stay healthier ( 30 October, p 38 ). Your article never mentions that veganism isn't just about food, but also clothes, make-up, hair products, pharmaceuticals, ceramics, weapons and pretty much everything else. …

Your article on vegan substitutes draws on flaws in dietary science that were pointed out in an article you published two years ago ( 13 July 2019 ). This showed how most dietary advice is based on observational studies rather than randomised, controlled studies, a state of affairs that leads to contradictory guidance on things …

Coupled with insulation and draughtproofing, heat pumps are very good for warming buildings sustainably, but they cost more than boilers and are more complicated ( 23 October, p 9 ). While reliability is excellent, repairs by skilled technicians (if needed) are costly. And knowing how to run a heat pump optimally is difficult when some …

Your article on the possible origin of domesticated horses has some important wider implications ( 30 October, p 18 ). These relate to the realisation that languages as diverse as modern Welsh and classical Sanskrit have a common root, which has led to a search for the origins of a Proto-Indo-European language . There are …

Regarding Annalee Newitz's look at the truth behind land used to fund some universities in the US – that is to say, the fact that it was taken from Indigenous people ( 2 October, p 26 ). My understanding is that pretty much all land in the US was stolen from these people, either by …

You quote Saleemul Huq saying that the $100 billion a year of "climate finance" meant to be pledged to support low-income countries is a "trivial" amount ( 23 October, p 36 ). He is right. To indicate how trivial, note that the UK government has budgeted half that for its covid-19 test and trace system …

Your article on quantum reality mentions a "superposition" of states, which means a particle can exist in all possible states at once before it is measured or observed ( 6 November, p 38 ). Researchers hope to do an experiment on a crystal 100,000 times more massive than used before to demonstrate quantum behaviour to …

"The vegan health illusion" doesn't discuss vegan diets in general, only highly processed vegan "junk" food, mainly plant-based meat alternatives ( 30 October, p 38 ). No health-conscious vegan will live on a diet of these products. Possibly the main consumers are people who have swapped meat-based junk food for vegan junk food. The simple …

Your picture of offshore wind turbines shows an interesting phenomenon ( 16 October, p 12 ). At the time the image was taken, the tide must have been running from right to left, as verified by the turbulent wake at the base of each turbine. Has anyone thought of retrofitting water turbines to the base …

Graham Lawton suggests the time may be ripe to introduce tradeable "personal carbon allowances" to ration greenhouse gas emissions incurred by our spending ( 23 October, p 26 ). It is also ripe for broadening this concept. Besides climate change, other global environmental onslaughts are beyond the reach of market forces alone to address: toxic …