Letters archive

I was fascinated and somewhat relieved to read of the possibility that the Incas' knotted khipu express a language ( 29 September, p 33 ). In Bolivia in 1988, a fellow backpacker taught me the craft of making bracelets from colourful knotted threads, called pulsera . I had never seen them before, and neither had …

You criticise Alessandro Strumia's unacceptable and biologically false comments on the abilities of female physicists ( Leader, 6 October ). His views highlight an appalling, continuing basal sexism that dogs the physical sciences as it does other fields. But to compare Emmy Noether's difficulty in getting a university position with Albert Einstein's life is perhaps …

As long as they don't have to deal with humans Ann Morgan reacts with grim realism to news that orangutans are exceptionally good at keeping their infants alive ( 3 November, p 8 )

Sofia Deleniv discusses challenges to the notion that self-awareness is a higher form of consciousness ( 8 September, p 28 ). It seems to me that it is merely a result of having a multicellular body. Consider an early animal with chemical, optical and mechanical sensor cells spread around its simple body. It already needs …

Roy Harrison is correct when he states that an electric car has a similar carbon dioxide impact to a petrol-powered hybrid car if the batteries are charged from a gas-fired power station with a carbon footprint of 400 grams per kilowatt-hour (Letters, 6 October ). But this is almost never the case. The UK generation …

The idea of regular fasting to make you healthier ( 20 October, p 30 ) seems to be based on the idea that humans evolved on what is now called a Paleo diet, periodically going without food for days at a time. But humans have adapted within a few centuries to be more tolerant of …

Faced with the problem of greater brittleness being associated with increased strength, nature tackles it by rearranging internal microstructures, as Liz Kalaugher points out ( 29 September, p 40 ). We see the same phenomenon in ceramics – and in that ubiquitous material, concrete. Also emulating nature, we often reinforce material with bundles of fibres. …

At its recent conference in Incheon, South Korea, the Intergovernmental Panel on Climate Change called for a reduction in meat-eating to help reduce global warming. In turn, William Nordhaus, the freshly elevated Nobel laureate in economics, recommended that households should pay a price on their carbon emissions, some of which indirectly result from eating meat …

So one in five want immortality ( 22 September, p 8 ). Perhaps they need to study the Greek myth of Tithonus. His goddess lover Dawn persuaded Zeus to grant him immortality, but forgot about the eternal youth bit . Loathsome old age pressed full upon him, he could not move nor lift his limbs, …

• Cholesterol is a lipid that animals use to build cell membranes ( 29 September, p 12 ). • On a long fuse: satellites with manipulators could be used to defuse an opponent's orbiting bomb ( 24 October 1968, p 176 ). • Sponges' spicules are made of silica ( 20 October, p 8 ).