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You report a study by Helen Fisher and others linking air pollution from vehicle exhausts with teenage psychosis ( 6 April, p 25 ). You say that it isn't clear how air pollution might be linked to psychotic experiences. The children studied were born in 1994 and 1995. The fuel additive tetraethyl lead was banned …

Adam Vaughan is right to note that the correlation between exposure to air pollution and teenage psychosis isn't proof of causation. One smoking gun, though, is that air pollution is consistently worst in areas where poverty is concentrated, with all the social and psychological stresses it entails. It is extraordinary that the study found that …

Harvey Whitehouse reviews evidence on religion's role in human civilisation ( 6 April, p 36 ). But he makes no attempt to distinguish between the differing social needs of women and men. Formal religions are staffed by a ruling elite of men who, I believe, have a fundamental goal of regulating women's sexuality.

Gilead Amit reports plans to send gram-scale craft to Proxima Centauri ( 13 April, p 32 ). Expecting that these could get a signal back to us is fantasy. The amount of power a 1-gram payload could generate can't be more than a few watts. For comparison, the New Horizons spacecraft uses a 15-watt transmitter …

A study investigated what people are willing to do voluntarily to reduce their carbon footprints, and concluded "not enough" ( 6 April, p 8 ). I think people would be happy to do far more if everyone had to do so. It is our leaders who need to be forced to make the necessary laws.

Adam Vaughan notes that the European Academies' Science Advisory Council urges the European Union to change its stance on transport, which is that curbing mobility is not an option ( 30 March, p 23 ). Social engineering has given us the transport situation that we have now: they built it, and we use it. But …

Vaughan suggests caps on personal travel to reduce carbon emissions. But if capped travel could be traded, a rich person could buy travel from poorer people who were happy to accept a market price for it. This would be equivalent to a fuel tax that raised the cost to that price and whose proceeds were …

Sam Edge suggests fitting street lights with motion sensors to save energy ( Letters, 16 March ). I would go further and provide a rolling corridor of light in rural areas. It would move along ahead of a moving vehicle. This might have the added benefit of "nudging" compliance with the speed limit if the …

Your article on chimpanzees losing culture brought back memories ( 16 March, p 16 ). I took an elective course in anthropology as a freshman at the University of Illinois in early 1961, but I had no real interest in the field. One day, our professor came in with a burly gentleman, who he introduced …

• The sculpture of human figures in the intertidal zone is by Antony Gormley ( 20 April, p 34 ). • Rhoetosaurus brownie may sound delicious, but the name of the giant dinosaur is Rhoetosaurus brownei ( 27 April, p 9 ). • Galactic brain: Breakthrough Starshot plans to go no further than our closest …