Letters archive

After reading the discussion of the traditionally accepted 8 hours of sleep a night versus a possible 6.5 hours as optimal for maximum brain volume, I wonder if the difference may be linked to our measurements. Before we had smart devices with sleep trackers, we would generally assume that the time we went to bed …

When considering the origin of life on Earth, note that it all runs on the same power system of ion gradients across a membrane. As this is universal, it must date back to a universal common ancestor ( 4 November, p 36 ). How could such a system have developed on early Earth with only …

There was no mention of the admittedly unfashionable panspermia proposal, the idea that life came from beyond Earth. While it doesn't explain the origin of life, it could, if true, mean that the first organisms didn't come into being here, but in a different environment. In this hypothesis, life on Earth began not when the …

The concept of quantised space-time may be the key to understanding the multiverse – and the requirement that the plethora of universes must display a wide range of properties that fortuitously result in a limited number being relatively stable and life-friendly ( 28 October, p 30 ). If the fundamental constituents of space-time were to …

Your article about chimpanzees seeking higher ground for tactical reasons reminds me of one of our cats. He would run upstairs for a better look if he saw something interesting in the back garden. What was curious was that not only did he have the nous to do this, he also had the orientation sense …

John Kitchen pushes the idea that Victorian homes (broadly) aren't suitable for heat pumps, suggesting they may have to be bulldozed. Heat pumps simply output heat, and physically can heat any building, full stop. It is true that cost, unsightliness and regulations may be obstacles, but these are artificial constraints. Equally, all buildings are far …

You published a timely article about preserving us from the possibility of being wiped out by Martian microbes brought back to Earth in study samples. I hope sufficient steps are being taken to prevent Earth microbes from contaminating Mars and elsewhere that we visit ( 4 November, p 21 ). It would be a tragedy …

I appreciate the more realistic approach to so-called ultra-processed foods in your recent article, but would like to make a couple of comments ( 28 October, p 40 ). Emulsifiers aren't all potentially harmful "additives" as implied. Many occur naturally in food we eat, such as lecithin (E322), found in egg and soya beans, and …

Further to Bryn Glover's call for names for the opening chapter of the proposed next geological epoch – the human-induced Anthropocene – I would suggest that an appropriate title for its first age might be "The End" ( Letters, 4 November ).