Letters : Lost lambs
Temuka, New Zealand
I am writing in response to Les Ward’s comments about the trialling of
Woolover lamb covers (Letters, 9 August, p 50).
The trial mentioned in the article did not deliberately set out to expose
newborn lambs to uncharacteristic and unnecessarily harsh weather conditions,
but highlighted the weather conditions that can and do occur in this region. If
none of the animals had been covered, the lamb losses would have been
considerably higher.
New Zealand farmers lamb in spring, when feed is plentiful and weather
conditions generally favourable.
However, the Canterbury Plains are flat and very exposed to southerly weather
fronts and in this area during spring, a southerly storm can hit very quickly.
The temperature can then drop 15 degrees in minutes. If this happens farmers can
lose many lambs through hypothermia.
Ward suggests bringing sheep down to the lowlands to protect the animals from
the weather but as Canterbury is a flat plain at low altitude that is obviously
not an option. Ward also mentions housing indoors. That option is not possible
in New Zealand, as a typical farm may have 2000 to 3000 ewes.
Before developing the Woolover lamb cover, I was a farmer in the south
Canterbury region and am only too aware of the devastation that bad weather can
bring to young lambs. My intention is to minimise lamb losses in New Zealand. I
do not condone any unnecessary cruelty to animals.
Letters : Lake was wet
Windermere, Cumbria
As George Turner says in his interesting article, the cichlid fishes of the
Great Lakes of Africa have indeed undergone rapid speciation, but that the
entire flock of 500 or more species found in Lake Victoria evolved within the
last 12 500 years is less well established than is suggested
(“Small fry go big time”, 2 August, p 36).
On the basis of coring data, Tom Johnson and his colleagues believe that the
lake was dry for some 5000 years before about 12 400 years ago and that no
refuges remained in the basin. Their evidence, while apparently convincing, is
not in agreement with earlier coring data. Moreover, the biological implications
of such events extend far beyond those affecting the cichlid fishes and are
difficult to reconcile with the situation that prevails today.
If Lake Victoria did indeed dry out so recently, not only its cichlid fishes
but all its other endemic animals must have evolved in this short period of
time. The latter include fishes of several families. Some of these are well
differentiated. Thus two catfishes belong to an endemic genus
Xenoclarias, and are adapted for life in deep water for which they have
acquired striking structural and physiological specialisations of the
respiratory system. Such specialisations generally take much time to
evolve鈥攎uch more than is sometimes required for speciation, though
Xenoclarias has also split into two species since it evolved in the
lake.
Rapid evolution by several families of fishes is not usual in a lake. And
where, if not in the Lake Victoria basin, did the ancestors of the present-day
endemic fishes, molluscs and crustaceans survive the drought? If Lake Victoria
became reduced in size, the animals present would not depart for refuges
elsewhere but would follow the retreating water. The last refuge to remain would
be in the Lake Victoria basin.
Letters : Nuclear trap
Teddington, Middlesex
May I suggest a couple of technical difficulties with the proposal to store
nuclear waste in exhausted oilfields
(Letters, 16 August, p 47).
Past performance being no guarantee of future results, we would need some way
of calculating the impact of erosion until the waste decayed to inert levels.
Just because an oilfield has been leakproof for millions of years doesn’t mean
it will be for the next few hundred thousand, especially since the very
extraction of this oil has disrupted the strata and may cause subsidence.
Oilfields trap light molecules such as water and hydrocarbons. Many
radioactive elements are heavy and might sink out of the trap and away, so only
oilfields that are sealed in every direction could be used.
Liquefied waste pumped into oilfield strata would be subject to separation by
both gravity and rock filtration, which could lead to a critical mass of fissile
material being concentrated in one part of the strata with unfortunate
results.
Today’s exhausted oilfields still contain large quantities of oil鈥攖he
technology for extracting oil has improved greatly this century. In future, we
might regret the radioactive contamination of this oil. Worse still, in a
thousand or a hundred thousand years’ time people might extract irradiated oil
without knowing the dangers of radiation.
Even if we close the whole nuclear industry tomorrow we still need to find a
way of ensuring that the nuclear waste we have already created is kept separate
from the biosphere until it’s safe. Pumping waste into oilfields is better than
pouring it into our seas and rivers, but it is still not acceptable.
Letters : Vote for dubbing
Ottawa, Canada
Previous comments on presenting foreign language films to English speaking
(hearing?) audiences favour subtitles over dubbing
(Letters, 23 August, p 48).
The reasons are logical, but there is still a sound reason for dubbing. My wife
has cataracts. While surgery may yet repair her eyes, she is unable to read text
more than 25 centimetres away. Nearly all the foreign language films that we
wish to see, either at the theatre or on videotape, use subtitles. For the time
being, therefore, and perhaps indefinitely, many great films are
unwatchable.
There must be many people who have partial sight, who can enjoy movies if the
screen is big enough, but cannot read credits or subtitles. So our vote goes for
dubbing. Better still would be dubbing plus closed-captioned subtitles for the
hard of hearing, as is common now on many TV shows. The artistic and
language-learning merits of keeping the original dialogue on separate channels
will have to wait for new technologies to mature and reach the marketplace.
Letters : Spam blocks
richardm@atrium1.advance. com.au
I enjoyed your comments about Switzer’s e-mail list
(Feedback, 19 July and
9 August).
It appears these lists are compiled by “spambots” who scan Web pages
and Usenet newsgroups for addresses. One would hope that these unqualified
addresses would be recognised as useless by other marketers, but it appears
not.
The initial ploy to foil these spambots involved changing one’s return
address in messages to a bogus address, such as nobody@nowhere.com, and
placing the real address in the text of the message with instructions for
legitimate correspondents to use that, rather than rely on the one in the
message header.
The spambots moved one step ahead, extracting addresses from the text of the
message itself. The latest is for spam haters to include in their messages
addresses of the sender’s service provider to automate the complaint process,
without flooding the Net with bounced messages.
The addresses typically used are: root@localhost,
postmaster@localhost and abuse@localhost.
I suppose it’s only a matter of time before
the spambots learn to filter out “abuse” and “localhost” from their mail lists . . .
Letters : Galactic spider
nc566@gre.ac.uk
I have theoretically managed to break the speed of light, c, without
gaining any noticeable mass. It’s quite simple. If you scale down the whole
Universe to the size of my bedroom, you can run from one wall to another
(effectively billions and billions of light years) in the space of 3.142
seconds.
Scaling this back up to the Universal scale, I have covered the entire
Universe in a matter of seconds, breaking the speed of light several
millionfold. Why are all these scientists making such a big fuss about this
faster-than-light travel business?
Incidentally, I did not encounter any alien races out there apart from a big
spider on my lampshade, which when scaled back up to Universal standards took up
the space of five whole galaxies.
Letters : Goodbye, France
douglas.graham@mcmail.com
Your article about Q-balls reveals that physicists at CERN in Geneva wish to
use large (1 gram) particles to induce proton decay and release large amounts of
energy (This Week, 30 August, p 18).
This does then seem to be a real supply of “limitless” energy. However, as
all of the particles in the Q-ball will be in the same quantum state (they have
no spin), the ball can be thought of as one particle and so will be about 10 000
times the Planck mass, meaning that it will instantly collapse into a small
black hole. This could lead to the sucking in of Switzerland and, hopefully,
France.
Letter
rochonda@em.agr.ca
Your article states that transgenic plants expressing viral genes can serve
as sources of genetic information for the formation of new viruses in plants. As
the scientist quoted in parts of this article, I would note, as I did at the
meeting, that the recombination experiments described were not conducted using
transgenic plants. Nor, incidentally, were they conducted with cucumber mosaic
virus. The findings from these as yet unpublished experiments cannot easily be
applied to what can happen in a “field of genes”.
Letters : Sensitive lobsters
Baulkham Hill, New South Wales
You are right to be concerned that the standard way of cooking lobsters is to
boil them alive
(Feedback, 16 August, p 84).
Contrary to your advice from the
director of the Maine/New Hampshire Sea Grant Lobster Institute, lobsters almost
certainly feel pain as do all sentient creatures. They do not have a single
brain but a chain of nerve centres running along the dorsal midline.
The Animal Welfare Advisory Council in New South Wales addressed this issue
in 1989. The council is appointed by the New South Wales government minister
responsible for administering the Prevention of Cruelty to Animals Act and
advises the minister on animal welfare.
With the assistance of the Restaurant and Catering Association of NSW, the
council produced a brochure describing how to kill crustaceans humanely before
cooking them or preparing sashimi. It is available from NSW Agriculture, PMP 10,
Rydalmere, NSW 2116, Australia.
Letters : Nets work
Basel, Switzerland
A recent article picks on the holes of a potentially life-saving health
intervention: insecticide-treated nets (ITNs) in Africa
(This Week, 16 August, p16).
Much space was devoted to the work of a group, led by Bob Snow, which is
working in Kenya. Despite the fact that Snow and his colleagues claim scientific
neutrality in this argument, it is clear that they recommend withholding this
intervention in certain areas of Africa that are badly hit by malaria. Donor
agencies are bound to consider this argument.
We agree that we know little about the long-term impact of ITNs as compared
to the large amount of information we have now on their short-term impact.
However, the current scientific evidence does not justify halting an
intervention with such large potential benefits.
The data from Snow’s work that your article is based on are not without
problems. First, they fail to address the crucial issue of malaria as a cofactor
for other causes of severe disease and death.
Secondly, the comparison is entirely based on hospital data, which are well
known to be susceptible to many sources of bias.
There are many shadows in our knowledge of malaria as a disease, but we
should not let one ray of light lead us down the wrong way. Our argument is best
summed up by S. K. Sharif, the provincial medical officer for the Coast Province
of Kenya: “My personal opinion is use the nets. The reduction in mortality in
children under two will be more than the complications after three years of
life.”
Letters : Standard bearers
by e-mail
Can I remind Barry Fox that Microsoft’s plans to port Internet Explorer to
the Mac does not make it a world standard
(Forum, 30 August, p 46). There are
many people who look at Web pages using Unix or other mainframe systems for
which Microsoft solutions are unavailable.
Leaving aside the technical merits of the Internet Explorer versus Netscape
war, at least the latter writes software for a true cross section of world
computing environments.
Letters : Viral hysteria
Ames, Iowa
Kurt Kleiner’s article could generate hysterical fear of transgenic potatoes
that are immune to potato leaf roll virus because their DNA has been altered to
include the virus’s replicase genes
(This Week, 16 August, p 4). He fails to
mention that these potatoes should greatly reduce the occurrence of this
damaging virus, and as a result, reduce the use of chemical pesticides.
In potatoes grown commercially, the virus causes net necrosis (blackening) in
the tuber, making the potato unmarketable. Potato growers try to limit the
spread of the virus by applying large quantities of chemical insecticides to
kill the aphids that transmit the virus from plant to plant.
I made it clear in an article I coauthored (“Are there risks
associated with transgenic resistance to luteoviruses?”, Plant Disease,
vol 81, p 700), and in a document written for the meeting Kleiner covered, that
it is hard to imagine, in this case, how recombination could occur to produce a
viable virus. It is even more unlikely that it could result in a more dangerous
situation than that which we live with now: regular outbreaks of a serious
virus, and widespread pesticide use to control it.
The author should stop crying wolf and focus on applications of technologies
that actually pose significant risks. With the alarmist attitude expressed in
his article, would we ever have approved such far riskier projects as the
feeding of the live Sabin polio virus vaccine to our children?
Letters : Fat matters
London
In Robert Pool’s report on new drugs for combating the epidemic of obesity in
the Western world
(“Things can only get thinner”, 23 August, p 22) there is a
box entitled “Can you be too skinny?” Here it states that for body mass indexes
(BMIs) up to 27 or 28, weight is not closely related to mortality, but that
above BMIs of 28 or 30, “extra fat increases blood pressure and cholesterol
levels, makes a heart attack more likely and, by triggering diabetes, can lead
to kidney failure”.
While this may be very comforting to the population at large, which has an
average BMI of about 26, several studies have shown that mortality is an
inadequate measure of the consequences of being overweight or obese. Instead,
research shows that healthy body weights may be better determined by using
criteria based on risk factors and morbidity (illness).
The British Regional Health Study followed almost 8000 middle-aged men drawn
from general practices in 24 British towns. It shows that men with BMIs between
22 and 24 have the lowest risk of experiencing heart attack, stroke, diabetes or
death from any cause. Levels of a wide range of risk factors for cardiovascular
disease, including blood pressure and blood cholesterol, rose progressively from
BMIs below 20.
The study has previously explored the J-shaped relationship between BMI and
mortality and shown that the excess deaths in the very lean men is largely due
to cancer and other smoking-related diseases. In men who had never smoked the
lowest mortality was observed in those with a BMI of 20 to 22.
Clearly, even within the “normal” range of BMI (20 to 28) it is better to be
leaner, and the optimal healthy body mass index for adults appears to be about
22. As the proportion of the population with BMIs over 30 has doubled in the
past decade, the implications of these findings for public health are
considerable.
Letters : Death cloud
Epping, Essex
I read “What really killed the dinosaurs?”
(16 August, p 22) with great
interest, particularly Allen and Yabushita’s proposition of an encounter with a
giant molecular cloud (GMC). I came to a similar conclusion in a paper entitled
“On the origin of change”, submitted 17 years ago to the Journal of the
British Astronomical Association.
In it I showed that by isolating major changes of evolutionary fortune (good
and bad), six predominant periods of development can be derived for the last
half billion years. Of these, three, covering periods from 535 to 500, 310 to
275 and 75 to 60 million years ago, are each separated by approximately 225
million years. Of the remainder, one spanning 390 to 360 million years ago and
one of about 150 million years ago do likewise. Since the Solar System’s
galactic “year” is of this order, the Sun will have been in the same region of
space for each of the two sets of correlations.
Most occasions of marked change in the Earth’s environment could therefore be
explained by its passage through just two GMCs. A third GMC encounter would be
required for the remaining period, occurring between 195 and 240 million years
ago, but either there was no previous encounter (about 442 million years ago)
with this particular GMC, or fossil evidence for a change at that time is
minimal. Intriguingly, by continuing with the 225 million years’ periodicity, we
would be within this third cloud right now鈥攁nd one wonders if humanity’s
effect on the extinction rate is masking a “natural” one.
Though opinions may differ regarding the exact timing of specific events,
there can be no doubt that on the large scale they do coincide spatially. Of
course, by knowing the Sun’s galactic orbital rate, together with the
approximate timings of evolutionary events, it is possible to estimate the
extent and position of these GMCs. I calculate that one cloud should lie between
galactic longitudes 20掳 and 50掳. Perhaps someone may care to look.
Of course, the weakness in trying this sort of geo-astronomical correlation
is the error margins involved in attempting to date evolutionary events (whose
resolution is measured by palaeontologists in sediments, rather than millions of
years). Until better techniques are developed, the error bars can be modified to
fit many theories, especially in a problem crossing two disciplines.