Human limitations should not constrain mathematics
From Alistair Fraser, Whanganui, New Zealand
Terence Tao makes a persuasive case that mathematics is about more than just producing answers: discoveries must be understood, explained and incorporated into a wider body of knowledge. But I wonder whether his concern that AI may produce mathematics faster than mathematicians can absorb it contains an assumption worth questioning (19 September, p 7).
Why should the future rate of mathematical discovery be limited by the rate at which humans have traditionally been able to process it? If AI becomes capable not only of discovering mathematics, but also of verifying, organising, connecting and explaining it, then human comprehension needn’t disappear 鈥� but it may cease to be the bottleneck.
Consequently, rather than diminishing, the role of mathematicians could instead shift towards deciding which questions matter, interrogating machine-generated knowledge, recognising significance and determining where discoveries should lead. The greater danger may not be that AI produces mathematics too quickly, but that we try to accommodate a fundamentally new capability within structures developed for an age when human intellectual labour was scarce.
New muscle-boosting drugs may be misused
From Jon Arch, Welwyn Garden City, Hertfordshire, UK
Michael Le Page’s article about drugs that prevent muscle loss reminds me of the medication clenbuterol. It is used to treat asthma, but also causes a rapid, remarkable increase in skeletal muscle mass in rats and mice (5 September, p 20).
Unsurprisingly, some years after this was first discovered, several weightlifters suddenly found that they needed clenbuterol to treat their asthma. It is now banned for International Olympic Committee-tested athletes. Will the same fate await myostatin and activin antagonists?
Our carbon-dating efforts are safe from solar storms
From Eric Kvaalen, Les Essarts-le-Roi, France
Bryn Glover is concerned that carbon-14 dating may be inaccurate because the amount of this isotope in the air varies, particularly after intense solar storms. He needn’t worry: it has long been known that the amount varies, and old wood is exactly the way we get out of this problem (Letters, 19 September).
Over the past several decades, researchers have created a calibration curve for carbon-14 dating by looking at the pattern of thick and thin tree rings in old wood and thereby identifying when the tree lived. Then, by measuring the carbon-14, the calibration is achieved and can be used for other organic material.
Psilocybin could be a boon for chemotherapy patients
From Jane Giffould, Halstead, Essex, UK
I was delighted to read that psilocybin, the psychedelic compound in magic mushrooms, may one day alleviate the numbness and tingling experienced in peripheral neuropathy, which I have had for the past nine years as a result of chemotherapy. This side effect has been growing for me, while the drugs that are meant to help clear it have had zero effect. If psilocybin works, then bring it on. I just hope it doesn’t interact with the countless other chemo-related drugs to generate even more side effects (12 September, p 10).
Immune system’s role in labour may be even greater
From Ahmad Aljesirawi, Amman, Jordan
The finding that immune cells may kick-start contractions in childbirth is fascinating. I wonder whether there could be another connection worth investigating (19 September, p 12).
Research on human attraction has suggested that body odour may sometimes influence mate preference, including possible preferences related to differences in certain immune system genes. In simple terms, we may sometimes be attracted to partners whose immune-genetic profile differs from our own.
Could these immune differences between the mother and father 鈥� and therefore between the mother and fetus 鈥� have any relationship to the immune signalling described in this new research? For example, could recognition of fetal or paternal antigens contribute, directly or indirectly, to the activation or recruitment of maternal immune cells in the uterus near the end of pregnancy? Could this influence cytokine or chemokine signalling, macrophage activity or the mitochondrial transfer to uterine muscle cells described in the study?
I am not suggesting that this is the established mechanism, but I think it raises an interesting question: could the immune system differences that may play a role in mate attraction also have a later biological role in pregnancy and the initiation of labour?
Oral flea treatments for pets may be damaging, too
From Greg Nuttgens, Porthcawl, Bridgend, UK
Discussing the effects of flea treatments on the environment, Jens Christian Jensenius suggests that oral methods may not pass through the animal. But some of the chemicals used in worming treatments for sheep and cattle, which are similar to flea treatments, do pass through the gut. They can have a serious effect on dung beetles and other insects, which feed on and break down dung, reducing biodiversity and slowing down the incorporation of dung nutrients into the soil. These chemicals should be banned for both farm and domestic use (Letters, 12 September).
Dark matter is still elusive despite potential sighting
From Ulrich Seydel, Melbourne, Australia
In the search for dark matter, aren’t researchers putting the cart before the horse? We know dark matter has gravitational effects, but the rest is, to my knowledge at least, conjecture (12 September, p 4). Building hypotheses about dark matter and designing experiments based on those hasn’t been very effective over the past few decades. Wouldn’t it be more productive to stop guessing and continue observing with a wide-open mind?
For the record
Albert Einstein鈥檚 general theory of relativity explains gravitational time dilation (12 September, p 22).
2.5 million animals were used in scientific research in the UK in 2025 (19 September, p 32).