No-go gravitons
A successful quantum theory of gravity must match those predictions of the current theory, general relativity, which have been confirmed by scientific observation (18 March, p 32). This means that it must predict the irregularities in Mercury’s orbit, time dilation approaching a massive object, the decay in the orbits of binary pulsars due to gravitational waves and the bending of light by a gravitational field (lensing).
As general relativity is founded on the principal of equivalence, that gravitational mass and inertial mass are equivalent, quantum gravity must include an interaction between gravitons and the Higgs boson, the “god” particle postulated to give other particles their mass. It is not obvious how a theory based on gravitons will do any of this.
We have named gravitational waves correctly
Likeable memes
Mary Midgley, in criticising Daniel Dennett’s work on religions, is wrong to suggest that memeticists only apply their methods to doctrines they dislike and that this is irrational and unscientific (25 March, p 24). One only has to look at the online Journal of Memetics () to see that a wide range of topics are studied, including such diverse topics as the evolution of language, financial markets, and yes…memetics itself.
Research often starts from a familiarity or liking for a particular subject as much as from a concern about it 鈥� my own PhD thesis was on the memes to be found within the new ideas and techniques that have reduced post-surgical pain and nausea in recent years. Religions, viewed through a memetic lens, are yet another form of human cultural evolution, and it is important they be explored and commented upon from a variety of perspectives.
Puny men welcome
Your recent article on the continuing evolution of humans alludes to research attributing the disproportionately high IQ of Ashkenazi Jews to their adaptation to restrictions on the trades they were allowed to practice to earn a living (11 March, p 30).
True as that may be, let’s not forget the importance of sexual selection: I come from this lineage and can attest to the preference of Ashkenazi Jewish women, in this culture of The Book, for brainy men suited for Talmudic interpretation, however puny, over men with greater physical prowess. As I supposed that I had stepped out of this tradition, I’m astonished to realise that I have carried this preference through to my own children 鈥� extremely verbally gifted products of my selection of their brilliant though supremely impractical Irish-American father. In our information-oriented culture, this heritage, skewed as it is, works very well for them.
April Fool?
I noticed that the publication date of the issue of New 杏吧原创 I was reading was 1 April, so I looked for the inevitable spoof article.
It was the one about Microsoft keeping our online transactions safe (p 28). Right?
For the record
鈥� Part of the illustration in our story about Tiktaalik, the intermediate between fish and land vertebrates, was inaccurate (8 April, p 14). The bones coloured yellow and green in the diagram of the land-living vertebrate limb should be the other way round.
Tragic Piraha past?
Is it not possible that the article on the Piraha people of the Amazon overlooks the possibility of historical explanations for the current state of this particular group’s language and culture (18 March, p 44)?
The Madeira river region is hardly pristine wilderness. On the contrary, this area has witnessed centuries of interaction between indigenous groups and agents of the Portuguese Crown, Catholic and Protestant religious bodies, rubber trappers, foresters, road builders and settlers.
All these changes and their often catastrophic impacts have been analysed in any number of excellent historical works. Moreover, recent archaeological work has tended to emphasise the richness and complexity of the pre-Columbian cultures of Amazonia, and, if anything, to minimise the former distinctions drawn between these peoples and the civilisations of the Andean regions and Central America.
Assume then for the sake of argument that Everett’s ethnographic analysis is correct, and that the Piraha have, for example, an extremely simplified kinship system. That may in fact reflect purely historical transformations, such as death of elders in epidemics or in frontier violence, rather than any kind of innate or permanent characteristics of this group.
For this reason attempts to generalise “fundamental lessons in what it means to be human” from the present-day circumstances of this unfortunate people may be misconceived. Languages can be lost, conceptual worlds can be destroyed. At any rate any further research should at least include a strong ethnohistorical element to eliminate these possibilities before we all get too excited.
From Andrew Tucker
At first, your article on the Piraha people, who neither count nor write, seemed an exotic curiosity. But as I read on, everything seemed increasingly familiar. Being told that certain skills are essential, when you have done perfectly well without them until now; resenting arbitrary rules, and being told “there is only one correct way of doing things”; going to classes mainly to socialise, understanding the concepts taught, but forgetting them as soon as you get home…I am sure I’m not the only person who feels that way about their computer.
London, UK
Farms and world water
In your articles and letters about failing water supplies, I have not seen much mention that improvements in agricultural practice, apart from dams and rainwater harvesting structures, can play a significant role in improving the situation (25 March, p 24).
Plants grow, streams flow, and groundwater may be recharged if enough rainwater gets into the soil profile. When a proportion runs off it contributes to soil erosion and increased severity of flooding, as well as leaving soils of croplands and pasturelands suffering drought in the root zone. A range of unwise forms of land use and management can cause serious loss of porosity in the soil, which reduces its permeability and unnecessarily wastes water.
The development and spread of zero-tillage farming systems 鈥� those rich in organic matter from residues of crops and of cover-crops grown in rotation 鈥� have now covered millions of hectares in subtropical and tropical Brazil and other countries since the 1970s. These systems show that dire land damage and water loss can be reversed and almost eliminated when soils regain their porosity, as mediated by organisms in the soil. The permeable cover of plant residues also protects the soil from erosion by rainfall.
These improvements have minimised runoff and erosion. Greater farm output/input ratios show that rainwater, farm energy and applied inputs are being used with greater efficiency. Flood severity is much reduced and base flows of streams and rivers have improved.
These and other agro-ecologic and socio-economic benefits follow primarily from improvements in land husbandry and the associated restoration of short-circuited parts of the hydrologic cycle. Mechanical solutions and managing demand are not the only answers to water problems.
Community TB watch
I would like to correct a point in your report of our study on families and TB (25 March, p 6). We compared two types of treatment observers: (a) family members and (b) community volunteers, not, as your report stated, family members and health workers. The point of the study was that in the sites we looked at in Nepal health workers weren’t suitable as treatment observers, as most patients live too far away from health workers to make this feasible.
We concluded that both family members and community volunteers can make good observers and are thus appropriate for these areas where patients’ access to health services is poor, and probably other areas as well.
Also, it’s not really right to say there is no stigma attached to TB. The stigma remains, but its impact is reduced, because patients don’t have to take their medication so publicly.
Sahara then and now
The interview with Spencer Wells is extremely interesting, but I am bewildered by Wells’s remark: “… humans originated around sub-Saharan Africa. But how could they have crossed the Sahara to populate the rest of the world? I was riding through it a couple of months ago. It is unbelievable. It’s a sea of sand with no water in sight, stretching for thousands of miles” (25 March, p 48).
Humans crossed the Sahara of 60,000 years ago, not the modern desert. Surely it is common knowledge that the climate of the area was vastly different then. All sorts of fossils and artefacts from ancient times have been discovered in the Sahara, including ancient rock carvings.
For art's sake
While expressing his doubts about new DVD copy protection schemes, Edward Felten asks why the public should support digital rights management software (11 March, p 42). As a recording artist who has watched the collapse of the music business at first hand, I think I am in a position to answer this.
If sharing movies becomes as common as sharing music, DVD sales will inevitably drop. The film industry will have less money overall, a wave of consolidations and layoffs will follow, and studios and production companies will stop financing projects that they think are in any way risky.
Instead they’ll concentrate on the lowest common denominator: star power, sex, violence 鈥� obvious and recycled stories. This is exactly what has happened in the music business in the last 10 years: promotion budgets directed primarily at “pop” artists (good looking performers of questionable artistic merit) or at music concerned primarily with violence or sex.
The public should support all “digital rights management software” because, in the end, it means that more movies will be produced, and they will be of better quality. Copy protection is fair and it’s right and it’s good for art, for artists and for anyone who enjoys art.