Myco-coco
Colin Barras credits the leaf shape of the coco de mer tree for the high level of nitrogen and phosphorus in the soil around the tree, as it funnels rainwater and the nutrients it picks up down the trunk, but there is another explanation (14 February, p 13).
The dense, fibrous root zone of this palm plays host to a community of mycorrhizal fungi that ferry otherwise unavailable phosphorus to the tree. The fungi also provide carbohydrate energy to the nitrogen-fixing bacteria in the soil.
Rainwashed nutrients may well play a role, but unless the researchers measured the microbial levels in the root zone the contribution of these organisms should not be ignored.
Hastings, East Sussex, UK
For the record
鈥� An error landed in our story on meteors (21 February, p 13): Manuel Moreno-Ib脿帽ez is affiliated to the Institute of Space Studies (CSIC-IEEC) in Barcelona, Spain.
Baby boom and bust
Health minister Beatrice Lorenzin needn’t worry about Italy’s falling birth rate (21 February, p 8).
If each woman has 1.39 children, it will take about 49 generations for the population to fall to 1 (at which point Italians will presumably go extinct).
There’s nothing to fear from a lower population. Historically, Italy has always had a lower population than now.
Les Essarts-le-Roi, France
Dangerous dance
I was upset by the bad press given to Scottish country dancing by Roger Malton (14 February, p 55).
This type of dancing should certainly not be high impact, nor cause any twisting if done in proper light shoes on a suitable floor. It is in fact very healthy exercise for both mind and body with a large “feel-good” factor, and very few resultant injuries.
I started Scottish country dancing nearly 60 years ago and recently held a ball to celebrate my 80th birthday. Most of the dancers were not young, but they were certainly all fit and energetic.
Coton, Cambridgeshire, UK
Megaflood folly
In his article on megaprojects, Michael Marshall discusses flooding the Qattara depression in Egypt (3 January, p 34). This is an old idea that will lead to the creation of another Dead Sea.
Evaporation will gradually increase the salinity of the water until a supersaturated salt lake is created. The salt water will seep under the desert sand and contaminate the underground freshwater reservoirs that supply the nearby oases of Siwa and Qara. Finally, the salt water will cause the groundwater level to rise and flood the oases in the desert.
Please proceed with damming the Atlantic or the Mediterranean instead.
Toronto, Canada
No proving god
Theists and atheists can at least agree on one important statement: “There is no such thing as god” (21 February, p 54).
For the theist, this isn’t because god isn’t real, but because god isn’t a thing. God by definition is the author and sustainer of creation; not an item within it.
Faced with creation, a theist draws the conclusion that a creator is responsible. Trying to pin god down using the scientific method is like attempting to experience the creative powers of Beethoven through chemical analysis of the ink on his manuscripts. We can do it, but it doesn’t get us very far.
London, UK
Cancer coaster
Peter Borrows asks if roller coasters could be used to treat brain cancer (14 February, p 55). The answer is no.
The brain produces cerebrospinal fluid. Most of this fluid passes out to bathe the outer surface of the brain and spinal cord, from where it is reabsorbed. Anything blocking this flow, such as a tumour, will lead to a life-threatening increase in pressure within the brain.
A sudden change in the position or motion of the head, such as on a roller coaster, may move a tumour away from the drainage channel, unblocking it and temporarily relieving the pressure. But this is only a temporary measure and surgery is still required to remove the tumour.
Maidenhead, Berkshire, UK
Microbial gold
I don’t think it is disputed that there was some biological contribution to the formation of the gold deposit in the Witwatersrand basin (7 February, p 11). Since its discovery, various theories have been put forward as to how the deposit formed, including sedimentation, hydrothermal processes and precipitation by microbes.
That gold can form under anaerobic conditions is well known and by the late 1960s photomicrographs clearly showed the close association of some of these minerals with microbes, but this is relatively rare. It is generally believed that the Witwatersrand gold originated in the Archean greenstone belts to the north, south and west. The current exposures of these rocks all contain gold and most have been or are being exploited.
Much of the gold now lies in conglomerates believed to have been laid down in fluvial fans. I understand that only in the distal parts of the fans in the Witwatersrand is there a biological association with minerals, mainly gold and uraninite.
Barton on Sea, Hampshire, UK
Myco-coco
This is a very good point, and the researchers are looking into options to study the potential relationship between coco de mer and mycorrhizal fungi.
Is anyone out there?
John Bailey’s pessimistic view that a lack of alien visitors indicates there are no aliens out there (21 February, p 54) carries with it two hidden assumptions: an advanced civilisation will aspire to interstellar travel, and they will develop the means to do so.
It may be that interstellar travel cannot be achieved on timescales that are meaningful to living organisms. Voyager I, humanity’s most distant space probe, won’t actually leave the influence of the sun’s gravity for another 17,000 years, let alone reach another star.
Anything we are likely to build in the foreseeable future won’t do more than shave a few thousand years off that, and what civilisation is going to sit around for 10,000 years awaiting an answer from a probe it’s unlikely to even remember it sent?
It is now over 40 years since we even sent anyone to the moon, and a combination of economics and politics has stifled our ability to get out of Earth orbit since then, let alone reach for the stars.
Similarly, alien civilisations may be out there, but have never managed to visit us simply due to budget cuts.
Monkseaton, Tyne and Wear, UK
No need to frack
You are correct. We meant to say that importing more gas to the UK could increase demand for Russian gas in other countries.
No need to frack
In examining whether the UK should press ahead with fracking for gas, you write that a lot of imported gas originates in Russia (14 February, p 10).
But according to government figures, the gas we import comes primarily from Norway, Qatar and the Netherlands. The prevalent misconception that we need to frack to keep the lights on, and that we get our gas from Russia, makes it hard to have a sensible debate on energy security, and whether we should risk going “all out” for shale gas in this country.
As a resident of the north of England, I’d much prefer to see investment in energy sources that start us on the path to displacing fossil fuels.
York, UK
Predicting trouble
Hal Hodson draws our attention to the increasing prevalence of automated systems that tend to be driven by predictive equations (7 February, p 30).
These equations often have one thing in common: they rely on incomplete and proxy information to make their predictions. It is sobering to consider how accurate similar predictive equations are in fields like medicine or epidemiology.
Although valuable insights are gained from epidemiological studies, say, the predictive equations derived from them may not be good enough to predict individual choice, behaviour or risk. This can be put down to the use of incomplete, inappropriate or inaccurate indicators.
The public should be given assurance that the predictive equations used in banking or national intelligence meet exceptionally high standards.
Ottawa, Canada
The fine germ line
I agree with Michael Le Page’s argument for genetic alteration of embryos to treat those with major abnormalities (14 February, p 26), but where do you draw the line?
Congenital deafness? A genetic predisposition to cancer? A predisposition to stammering? I stammer, and am pleased I was not interfered with at conception.
I think that as technology improves and such interventions become routine there is the risk of laudable intentions towards perfection taking the whole thing too far. Some genetic disorders have benefits. Sickle cell disease, for example, confers a level of protection against malaria.
There will be other benefits attached to less-severe diseases that we are not aware of. We can never accurately foretell the future, so reducing our genetic diversity is not without peril. There may well be a value to nature’s lottery.
So yes, let’s have germ-line alterations, but these should only be for a very limited range of defined conditions, and never done without counselling and informed consent.
Bacup, Lancashire, UK
Some crap questions
Jessica Hamzelou describes the enormous influence intestinal bacteria have on the behaviour of the human body (14 February, p 8).
I wonder if this casts doubt on the validity of epidemiological studies on the diet. Could the benefit of a Mediterranean diet be dependent on a Mediterranean faecal biota?
To my knowledge, standardisation of faecal biota isn’t a feature of dietary surveys. Surely the effect of diet can only be meaningful if this factor is taken into account 鈥� especially if a faecal transplant can trigger obesity, as Hamzelou describes.
As a final thought, when one is choosing a faecal donor, it may not pay to choose someone with an active sporting lifestyle. The physical fitness might be compensating for deficiencies in the microbiome. Would it not be better to choose a healthy couch potato whose biota are keeping them fit, despite their inactive lifestyle?
Teddington, Middlesex, UK
Is anyone out there?
We ought not to fear attracting advanced aliens through interstellar signals (21 February, p 8). Considering the chances of any sentient life having the technology to detect, recognise and understand our signals, and the distances involved to travel to its source, we will be a very advanced race ourselves by the time they arrive.
Barnsley, South Yorkshire, UK
Is anyone out there?
John Bailey concludes that since we haven’t been bombarded with self-replicating alien space probes or spotted heat signatures in space, there probably aren’t any advanced civilisations living in our galaxy.
He seems to think that advanced races will have a “more is better” philosophy, but climate change is showing us that the opposite is the only intelligent long-term strategy.
If this is correct, then the more advanced an alien race is, the less visible they will be. It’s the quiet ones that are clever, not the shouters.
Hampton, Middlesex, UK