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Patricia Churchland's account of how our moral behaviour evolved to promote the well-being of human communities appears plausible, but she leaves two major issues out of her reckoning ( 28 September, p 44 ). The first is that these community-building behaviours apply only to our own community or nation. In relation to other communities, we …

Dean Burnett says "far from being a constant annoyance, teenagers may be the reason humanity is as smart and successful as it is" ( 14 September, p 56 ). Can't they be both?

You review Trevor Paglen's exhibition that seeks to highlight how prejudice is tainting AI ( 12 October, p 30 ), and Ramon Lopez de Mantaras predicts that bad algorithms will lead to injustice (Letters, 12 October, p 30 ). We want AIs to be superhumanly smart: to do things that we might never be able …

Adam Vaughan says that climate activists should be "embraced, rather than condemned" ( 19 October, p 23 ). I agree that Earth's resources need to be managed with regard to climate change. But Extinction Rebellion activists cannot achieve their aims because these are just not realistic, though they do move the centre of gravity of …

I have campaigned for greater awareness of the social and political implications of climate change for at least three decades. I recall reading environmental writer Rachel Carson as a very young man. I greatly welcome the activities of Extinction Rebellion, and was pleased to read Vaughan's viewpoint . Throughout those decades, there has never been …

Your report on vanishing glaciers in the European Alps is alarming, but there is worse news ( 21 September, p 8 ). Glaciers in the Hindu Kush and Himalayas are melting at a similar rate to those of the Alps. Most large rivers in Asia – the Indus, Ganges, Brahmaputra, Mekong, Yangtze and Yellow – …

BP makes a clear call for decisive and immediate action. Its group chief executive says: "The world needs to take urgent action... it is critical that everyone plays their part." Apart from the assertion that our growing world really needs ever more energy, the rest of the statement would, taken at face value, be worthy …

Camille Ferdenzi has discovered that each person's scent is unique ( 12 October, p 42 ). My dog tells me that her dog could have told her that, if she had asked.

For Elon Musk to give the name Starship to a rocket intended to go to Mars might be considered something of an exaggeration ( 5 October, p 5 ). It is, though, nothing compared with the hype of suborbital hops promised by Virgin Galactic.

• Couldn't see the trillions for the billions: the estimated number of trees in boreal conifer forests is 0.74 trillion ( 5 October, p 34 ). • Check, mate: a game of chess is won when one player's king is in check and they have no way to remove the threat (Feedback, 7 September ). …