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If advanced ETs do exist in our galaxy, we have the technology to find them: 1000 radio receivers of the same size as the Arecibo telescope may be able to detect an Earth-like civilisation up to 13,000 light years away. The real challenge for us – and perhaps for ETs – may be to persuade …

After reading the rather worrying story "US science coverage is biased against people with names not of British origin", I found myself doing exactly what the article predicted: the only name I could remember was that of the Birmingham City University expert, Marcus Ryder ( 26 September, p 14 ). I had to re-read the …

James Wong makes the oft-repeated claim that monocultures give greater crop yields from a given plot of land ( 3 October, p 24 ). As I understand it, and as past research indicated, monocultures enable the highest yield of a single crop from a given plot, but polyculture can generate a higher overall yield, spread …

• A picture in our exposé on the plight of giant river fish was mislabelled ( 3 October, p 41 ). Both fish on page 43 were actually American paddlefish.

Caroline Williams highlighted the complex mechanisms involved in staying upright ( 10 October, p 34 ). As an ear, nose and throat doctor with experience in treating balance disorders, I do feel this subject is underappreciated. In particular, I am aware of the link between balance and mental health Williams described, especially anxiety. I recall …

I cured my problem with loss of balance by accident. Williams is correct on at least two counts: movement is the key and swimming doesn't help. During a period when I couldn't swim, I went back to jogging. Almost straight away, I experienced a feeling of euphoria when I stopped running and walked for a …

In 1947, as a boy aged 6 on a slow voyage in a tiny cargo boat, moving our home from Cyprus to Aden, I was taught to go down stairs "navy fashion". Now a frail 80-year-old, as my balancing powers deteriorate, I would suggest that this advice significantly reduces my workload risk to the health …

It has been realised that the main technique for balancing a bicycle consists of many micro adjustments of the steering. This is much easier when travelling quickly and almost impossible when going very slowly. Might the equivalent process for correcting gait while on our feet be easier while running? If so, I think that humans …

Geoff Harding suggests that plummeting wildlife populations may mean humans having to deliberately take on some of their functions, like artificial fertilisation of plant species (Letters, 10 October). This brought to mind Maja Lunde's book The History of Bees , which is set against a fictional past, near present and future for bees and humans. …

You report work showing improvement in greenhouse gas emissions in countries embracing renewables, but not nuclear-powered nations ( 10 October, p 14 ). However, it could simply be that in the latter, the improvement had already taken place. Renewables are fairly new. Nuclear, by contrast, is a fair bit older. Countries with it have mostly …