Local ecology
Garry Hamilton’s argument that invasive species could be beneficial to ecosystems pertains more to continents than to islands (15 January, p 34).
The continuing damage to many island ecosystems by human-mediated invaders is enormous. However, effective biosecurity measures can prevent invasions, and this is being successfully achieved all over the world 鈥� even in blocks of mainland habitat such as New Zealand’s forested Maungatautari mountain.
A decade ago, only 12 native forest bird species survived there. But since the mountain has been surrounded by a 47-kilometre pest-proof fence, a dozen alien mammal species have been eradicated and the native bird population has been rebuilt to over 30 species. Sadly, several species once present are now totally extinct, but it is hoped that lizards, tuatara, frogs, bats and fish will be reintroduced.
The long-term sustainability of such management seems irrelevant to me: it would be an abdication of human responsibility not to save and restore unique species and ecosystems that would otherwise be lost. On continental scales we might have to remain interested observers, but on smaller scales we may be able to intervene positively.
Credible theories
I must object to the idea put forward in your feature on climate models that “it is the differences between [climate] models that help to ensure predictions are in the right ball park” (15 January, p 38). Splitting the difference cannot be relied on to give you the right answer.
Theories must stand or fall on whether they can produce credible predictions. There is a book in my local library, published several years ago, which is full of equations concerning US stock prices. Its overall prediction was that the Dow Jones index would rise to 60,000 points. In the same library there is also a book called The Crash of 2010.
We could have avoided a lot of financial pain if we had listened to someone with unconventional ideas that did not suit the establishment.
Economic evolution
There are many interesting parallels between the global financial system and natural ecosystems (22 January, p 6). It is not entirely surprising, given that financial institutions are able to pass on the information which encodes their operations, are subject to mutation and exist in a milieu which imposes selection pressures 鈥� all characteristics required for natural selection to occur.
It seems to me that the activities of financial institutions may even be determined more by Darwinian selection processes than by the people who are nominally in charge of them 鈥� though perhaps a degree of Lamarckism could be conceded.
However, as these institutions can exchange information in many directions, rather than simply from one generation to the next, perhaps the world of microbial ecosystems would prove a better comparison. The opportunity to compare bankers to bacteria obviously has nothing to do with the appeal of this idea.
Ape versus dog
You say that Chaser the border collie knows the names of 1022 items, more than any other animal (25 December 2010, p 8). Koko, a gorilla first studied at the University of Stanford, California, reportedly understands twice as many, and can actually use over 1000. Some humans can use even more.
Faecal phages
Given that “poo is a zoo”, it seems surprising that the report on the use of faecal transplantation to combat Clostridium difficile infections left out one of the most abundant members of intestinal fauna: the viruses known as bacteriophages (18 December 2010, p 36).
These viruses infect bacteria, and were in fact first identified in stool samples. It seems at least plausible that part of any beneficial effect of faecal transplants may come from phages in the transplanted stool destroying C. difficile, rather than from direct competition by colonising bacteria. Of course, after C. difficile has been eradicated by the phages, colonising bacteria could contribute to restoring normal intestinal fauna.
Seeing is believing
We should not be surprised by the strength of the anti-immunisation lobby (15 January, p 46). In rich nations, the majority of the population has never seen the diseases that we recommend parents vaccinate their children against. Immunisation has been so effective that diseases such as diphtheria and polio have all but disappeared.
To overcome the misinformation and resistance, we should use outlets such as YouTube and Facebook to show photos and films of children suffering from all the diseases which we immunise against. The anti-immunisation lobby uses shock tactics and social media to fight their cause. So should we.
Fat on the brain
You suggest that having a fat tummy may shrivel your brain (8 January, p 14). But an alternative explanation could flip this theory on its head: perhaps the brain changes in obese individuals are the cause of obesity, rather than the result.
The editor writes:
鈥� The study we reported showed a correlation between brain changes and obesity, but it is not known which comes first. A prospective, longitudinal study would be required to establish a causal relationship.
Middle-planet spread
In “Tales from an alternate Earth”, Hazel Muir suggests that if our planet stopped rotating, the oceans would settle in bands around the poles because of the equatorial bulge of the Earth (22 January, p 38). However, as she correctly points out, the bulge is caused by the Earth’s rotation 鈥� so with time it would disappear.
The Earth would then become more spherical and water would move once again. A look at the map 鈥� which shows by how much the Earth’s surface deviates from that of a perfect ellipsoid 鈥� suggests that central Asia and large parts of North America might then find themselves under water.
This said, I suspect that the tectonic upheaval caused as the Earth lost its equatorial bulge would cause much greater changes in the form of massive earthquakes and increased volcanic activity 鈥� so it may be best if we don’t perform the experiment.
Hazel Muir writes:
鈥� The bulge in the Earth would not disappear immediately if the planet stopped spinning: it would eventually become more spherical, but over a likely timescale of tens of thousands of years. The water, on the other hand, would shift over days or weeks, so oceans would be created at the poles, at least for a few thousand years.
Bitter beer
The drinking of “extreme” beers, as discussed by Lizzie Buchen, has interesting historical precedents (25 December 2010, p 60). Analysis of historic recipes indicates that beers strong in alcohol were also high in bitterness. For instance, the 1903 beer portfolio of Hammond’s Brewery in Bradford, UK, covered seven beers ranging from a basic bitter at 4.1 per cent alcohol by volume (abv) to a barley wine of 9.5 per cent abv. There was a linear relationship between bitterness and alcohol content (The Brewer International, 2001, 1, p 29).
It might be that bitterness levels regulate intake, so that high-alcohol beer would be drunk more slowly than lighter bitter, though other factors undoubtedly contribute. It is also interesting that some of the UK’s superstrength lagers do not follow this historic relationship, and are much less bitter than their alcohol content might suggest.
A sticky end
Kevin Scott asks if anybody can tell him which is the wrong end of a stick (22 January, p 27). On a trip to Trim Castle in Ireland, a museum guide informed me that the term “wrong end of the stick” derives from the practice of stirring a dung heap.
I don’t know if this story is true, but clearly sticks used for stirring would have a right end and a wrong one.
From Carol Primrose
As the granddaughter of a typesetter who worked before the advent of computers, I can assure Scott that the wrong end of the stick is the left-hand end.
As part of the printing process, lines of text used to be built up by adding metal blocks, embossed with letters and characters, to a metal frame called a “composing stick”. These were then inked, before being pressed against paper in the printing press. As this gave a reversed image of what was on the stick, the stick had to be set from right to left for the printed page to read from left to right.
Bishopbriggs, East Dunbartonshire, UK
Christmas P's
I looked into the “P versus NP problem” on Christmas Day (25 December 2010, p 24), and am happy to confirm that Presents (P) most definitely do not equal No Presents (NP). I claim my $1 million prize.
For the record
鈥� We incorrectly stated that Charles Derby was affiliated to the University of Georgia (22 January, p 14). He is actually based at Georgia State University in Atlanta.
鈥� In our feature about pain, we gave David Borsook the wrong job title (22 January, p 34). He is a neurologist, not a psychiatrist.
鈥� In Feedback (22 January) we said that the popular UK radio soap opera The Archers is set in the west of England. As many loyal fans of the programme were eager to point out, it is actually set in a fictional county called Borsetshire. According to dialogue in the show, Borsetshire seems to lie in the West Midlands, close to the non-fictional counties of Warwickshire and Worcestershire.