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I was interested in your piece on Leonardo da Vinci's "aerial screw" design for a helicopter. The story focused on theoretical modelling showing it could have flown with modern materials and motors. Readers might be interested to learn that in 2022, Austin Prete at the University of Maryland developed a quadcopter in which each rotor …

The fate of small, isolated bands of ancient Homo sapiens who died out during harsh conditions as they tried to establish a presence in Europe millennia ago reminded me of proposals for colonies on Mars. It seems any foothold there would need a continuous resupply of people, as well as essential supplies, to keep the …

So new research finds Denisovans had very impressive physiques( 28 June, p 10 ). Isn't this proof that sightings of abominable snowpeople and the like are, in fact, remnants of Denisovan communities living happy, untroubled lives away from so-called civilisation?

Lori Marino at New York University featured in our story on orca gifts ( 12 July, p 19 ).

Your headline "The enemy within" echoes the phrase that UK prime minister Margaret Thatcher used to demonise striking miners in 1984/85. The ruling class planned to crush the National Union of Mineworkers to pave the way for deregulation and privatisation. There was no "invisible rivalry", just open and often brutal class war. Cooperation and solidarity …

The discovery of wallaby and bandicoot bones on islands near New Guinea and in Indonesia is fascinating. The fact that ancient humans took them there alive implies that seeds of the animals' food plants could have survived in their guts and been deposited on arrival to colonise new land. The presence of disconnected populations of …

The story on human habitations on Mars that could be built from bioplastics filled me with horror. We have already polluted our own planet with plastics to such an extent that they are found everywhere and in every species. We are now proposing to pollute another world. Not only that, but the algae we end …

From 28 June, p 35

Geoengineering projects are nothing new: mining, coal, oil, etc. have impacts beyond borders and create mounting environmental problems. In the main, these industries are for profit and answer to shareholders. Because of the environmental damage they cause, we may need to consider geoengineering solutions that could have wider impacts too – possibly good, possibly bad. …

Amid debate about the capabilities of artificial intelligence, I asked one about socks going missing in the washing machine. It gave me a reasonable and rational reply. I then asked if the issue could be related to an interaction of relativistic effects of the spinning and electromagnetic oddities of the washing machine. To my surprise, …