Useful old age
You have recycled the old flawed reasoning why natural selection should not permit genes for longevity to exist (19 April, p 26). According to this dogma, the pressures of natural selection should weed out genes for longevity because they confer no reproductive advantage after an organism has become too old to reproduce. Therefore (the argument goes), the ageing process is not controlled by genes.
This argument makes sense if you are a shark or a shellfish, or any other organism that is left to fend for itself as soon as it is born. However, if it were true for mammals, evolutionary pressures would have selected for women who dropped dead the day after menopause.
A human child, unlike a newborn shark or shellfish, has virtually no chance of surviving till sexual maturity and propagating its genes unless there are older people around to provide food, shelter and protection. The presence of nurturing parents and possibly even grandparents increases the probability of a child’s survival and eventual reproduction.
Because young mammals depend upon older mammals for their survival, there is a logical basis for the emergence and propagation of genes for longevity.
Garry Hamilton writes:
鈥� If having healthy grandparents around provides reproductive fitness to a species, then of course evolution would select for genes that would delay the ageing process. But this would fall under the period of successful reproduction when everybody agrees that selection is still working. The key is the period after this time and the issue is not whether genes extend this period, but whether they shorten it in order to supply an indirect benefit to one’s offspring by eliminating competition for limited resources.
Plasmonic telescopes
I read with considerable interest the article on plasmonics (26 April, p 30). Am I right in understanding that a telescope could work on the same principle 鈥� that is, the concentrating of light falling on a large area and having it pass through an aperture smaller than the wavelength of starlight, for instance? If this worked, the manufacture of telescopes would be considerably simplified, as well as making them cheaper.
Renal rights
The fundamental biology in Archie Julien’s letter about kidney damage is flawed (3 May, p 24). Kidneys do not have to “filter out” additional substances such as phosphoric acid and sulphites. They merely filter in substances that are needed such as water, minerals and glucose. So people drinking soda pop are not in fact putting any extra strain on their kidneys at all.
The fact that Julien knew someone who drank lots of soda pop and died of kidney failure seems to have little or no relevance to the argument in hand. There has been no causal link proven between the two factors of kidney failure and soda pop drinking.
Anecdotal evidence is no evidence at all.
Spaying works best
Several large pharmaceutical companies have been working on a contraceptive vaccine for dogs (19 April, p 19), but to my knowledge they all abandoned it. Whichever technique you use to stimulate the response of the T-cells, you never reach 100 per cent. And while in a clinical trial a result of 98 per cent efficacy is very significant, it’s a disaster for marketing if the competition (spaying) provides a guaranteed 100 per cent result.
Thrill of throwing
The appeal down the ages of throwing stuff in water as “votive offerings” may well be hard-wired, but I am uncertain that it is due to a magpie-like attraction to brilliance and shine (5 April, p 47).
My one-and-a-half-year-old twin sons have already discovered the thrill of throwing stones and other objects into water. They will collect a good throwing stone where there is no water in sight and clutch it in their fists until an opportunity arises to cast it into the water 鈥� whether the sea, a lake, a puddle, the bathtub or the toilet.
This behaviour elicits peals of laughter and satisfied looks upon hearing the sploosh and watching the splash. Throwing stones or coins over the edge of a cliff or into a deep well elicits a similar response.
It’s impossible to know if their delight at throwing things into water is immersed in toddlerish visions of luck, love or wish-granting. But perhaps adult votive offerings are merely an excuse for the urge to hear the ploink and watch the rings expand.
More spam, please
New 杏吧原创 readers are concerned about their email boxes being bombarded with spam, and the need for better filters (3 May, p 24). However, they seem to have overlooked the benefits to be gained from all these spam messages. For instance, I have been accepting all offers made to me by email since the beginning of this year, and my penis is now 43 metres long.
For the record
鈥� In Comment & Analysis (3 May, p 23) we stated that 46 million people die each year from noncommunicable diseases. The correct figure is 33 million.
Letter
Surely if an asteroid is a porous pile of rubble (and hence not easily deflected by a nuclear explosion) it is likely to burn up and disintegrate as it enters the Earth’s upper atmosphere. In such an event the Earth’s environment will surely be affected, but not in the way of a direct impact. Earth might suffer a “nuclear winter” but not the firestorm scenario.
Eugenie Samuel writes:
鈥� According to Erik Asphaug, associate professor of earth sciences at the University of California, Santa Cruz, a more porous asteroid will burn up more quickly in Earth’s atmosphere. However, a killer asteroid several hundred metres across will enter the atmosphere at 20 kilometres per second. At this speed, it will spend about 1 second in the atmosphere before reaching the ground and making a crater. This is not nearly enough time for the asteroid to burn up, even if it is very porous.
Letter
Women have a wider field of vision than men. I can see quite well out of the corner of my eye, whereas my husband needs to turn his head to see objects at such wide angles. This is quite noticeable when he’s driving and, take it from me, can be dangerous at times.
This may even be associated with men’s inability to handle several tasks at once. They are great at concentrating entirely on one job, but ask them to remember to hang the washing out when the cycle is complete and their brain is overloaded.
Satirical patent
You publish details of my patent application for a TV “reality game show” format, where contestants compete to win a baby, without offering any hint of the truth behind the application (Feedback, 26 April).
Two years ago I published a novel on the Internet, called Nobody’s Child, about just such a reality show. I was so concerned that an unscrupulous TV station would take my satirical concept and make a real show of it that I used every legal means available to safeguard the idea. This included the patent application which, belatedly, your reporter has discovered.
Avoiding Armageddon
Your article about avoiding asteroid impacts seems to largely ignore timescales (19 April, p 36). The time between discovery of even a fairly big new asteroid and an impact could be as little as a few years. From that one would have to subtract both preparation and intercept times, leaving precious little time for any “soft” technology to work. Only a nuke would stand a chance.
Wide-angled vision
I was irritated by the article on girls needing wider computer screens to navigate in virtual environments (19 April, p 16). While I think it is entirely likely that women do perform better with wider screens, it is highly unlikely that this has the evolutionary origins you describe.
The notion that “Male hunter-gatherers roamed far afield, creating and following mental maps to do so. Women鈥ad more piecemeal maps centred on landmarks such as a homestead” is based on a long-debunked anthropological idea that the men went out on long-distance hunts all the time, while women stayed home and tended the fires.
Actually, studies of modern hunter-gatherers and forensic evidence suggest that the women ranged far afield gathering edibles each day, while men stayed largely at home, only occasionally hunting.
It seems more likely that the effectiveness of women in virtual environments is hampered because they are more peripherally conscious, with less attention focused in a narrow field in front of them. Studies have shown that women are more conscious of their lateral personal space, feeling uncomfortable when intruded on from the side, whereas men are more conscious, and defensive, of their frontal personal space.
Women have been forced evolutionarily to become more dependent on their peripheral senses, not only in order to complete their tasks while still minding what is happening with their children, both in defence of them and in defending them from themselves, but also because successful gathering requires a particular type of unfocused pattern recognition.
DU alarmists
The Royal Society is accused of not being firm enough when it argues that the risks to health from internal exposures to depleted uranium are uncertain. According to Sean Foley (3 May, p 24), we should simply accept the recent report from a new group calling itself the European Committee on Radiation Risk (ECRR), which claims that radiation risks are massively underestimated by the approach of the International Commission on Radiological Protection (ICRP), and should declare that inhalation of even small amounts of depleted uranium is likely to lead to large numbers of cancers.
There are undoubtedly uncertainties in estimates of the risks to health from the inhalation of radioactive particles, as discussed in the two Royal Society reports on depleted uranium, but a considerable body of evidence from human exposures, animal exposures and in vitro experiments suggests that the risk estimates derived from ICRP models are not very wrong. Indeed, a recent review suggests that the ICRP approach may overestimate rather than underestimate the risk from “hot particles” (Journal of Radiological Protection, vol 5, p 28).
Depleted uranium is only weakly radioactive and there is no convincing epidemiological evidence that there is any substantial excess of cancers among workers in the uranium industry. Similarly, ICRP models suggest that large intakes would be required to produce any substantial increased risk of cancer.
The very high risk estimates in the ECRR report are based very indirectly on several small, highly contentious epidemiological studies, most of which have not been published in peer-reviewed journals and have been carried out by the authors of the ECRR report, who have a clear anti-nuclear agenda. Sadly, there is little science in this report, as the political agenda of the authors has prevented them from coming to a balanced and independent assessment of the literature on radiation risks.
Soldiers and civilians involved in the conflict in Iraq need the best possible estimates of the risks of exposure to depleted uranium. It is irresponsible for anti-nuclear groups to use them as pawns in their attempts to massively over-inflate the estimated risks from exposure to internal radiation.