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Sandy Henderson, arguing for meat production, says that this is the only practical way to farm much of the north and west of the UK and Ireland (Letters, 1 February ). He omits the original and best land use for much of that region: forest. We shouldn't plant short-lived industrial conifer plantations – though there …

In the past, forests were considered part of the farming economy . Their resources could still be used to cut down carbon pollution in other ways. If we fed pigs on the dropped nuts and undergrowth, maybe we could have occasional pork chops, as pigs are very good at turning food waste into crackling.

The UK's Committee on Climate Change proposes that airlines and oil companies should pay for a colossal tree-planting drive ( 1 February, p 15 ). How much would this reduce the area of land dedicated to producing food in the UK? I wonder whether this is a good idea in a world that has a …

Readers discuss making towns more pedestrian-friendly (Letters, 25 January ). One thing that my 40 years of highway engineering work has taught me is that some drivers believe themselves to be expert highway design engineers. I agree with Rob Wheway that play space should be part of development, including on-street play space that allows shared …

Wheway rightly points out the importance of children being able to play safely in our streets. But cul-de-sacs are socially isolating and make direct pedestrian movement difficult, encouraging higher vehicle use. The solution is to build and rebuild roads on the shared space principle, with constant priority given to pedestrians and vehicles able to move …

You report that Neanderthals may have climbed an active volcano soon after it erupted ( 1 February, p 14 ). I suspect that there were Neanderthals who were protoscientists. They would, by observation, experiment and deduction, make startling discoveries. One might have been that a person who walked up a live volcano with a dry …

Donna Lu says face recognition needs to be regulated ( 1 February, p 23 ). It may already be. The EU General Data Protection Regulation , which wears a Union Jack hat as the UK Data Protection Act 2018 , covers cases in which it is possible to identify an individual directly from processed data.

Your article about recycling electric car batteries was necessary but depressing ( 16 November 2019, p 12 ). I remember the car industry being very keen 10 years ago to tell us that it was designing cars for the whole life cycle, including recycling. It is ironic that the greenest cars now seem to have …

Michael Vandeman, asking whether we can draw a line between life and death, questions whether frozen Canadian frogs are dead or alive (Letters, 11 January ). They are very definitely alive, as they aren't entirely frozen. For example, Rana sylvatica , the North American wood frog, has biochemical adaptations that prevent more than about 75 …

• Research into adding human genes to pigs to try to prevent donor organs being rejected could solve the problem of the shortage of human donor organs, as organs from normal pigs trigger a very strong attack from the immune system ( 1 February, p 10 ). • It was December 2019 that was the …