Tax Dollars at Work
Despite Barack Obama appointing scientists to top posts, I hardly think this qualifies him personally to be named in the “Scientific American 10.” His inclusion pales beside the favor bestowed to the others on the list who have actually done some real work for science and humanity.
Catherine McBride-Bergum
Virginia, Minn.

Although your infatuation with Obama is most likely impervious to facts, I would like to point out that federal R&D spending increased 41 percent in inflation-adjusted dollars over the course of the Bush administration. Also, Bush’s spending on embryonic stem cell research, though more restricted than you may have liked, represented a rather substantial increase over the Clinton administration, during which embryo-destructive federal research funds were essentially zero. Scientific American’s praise should be reserved for those who actually perform the hard work of advancing scientific knowledge, not those who merely allocate money they did not earn to researchers they will never meet.
Greg Pitner
Austin, Tex.

Soil Welfare
David A. Vaccari’s “Phosphorus: A Looming Crisis” usefully called attention to the critical role of phosphorus as a plant and crop nutrient and to possible future scarcities and constraints. But his focus on it as a fertilizer neglected its abundance in most soils. There is usually 10, 20, sometimes even 30 times more phosphorus in the soil than the amount in “available” forms that plants can readily utilize. The large amount of unavailable phosphorus is continuously, though relatively slowly, converted into available forms through the activity of soil microorganisms, many of which are known as phosphobacteria.

Without these microorganisms, plants could not have been growing in the earth’s soils for more than 400 million years. Ironically, the use of inorganic fertilizers can suppress roots’ and microorganisms’ production of the phosphatase enzymes that are essential for making phosphorus available for plant use. This inhibition is similar to the way that adding inorganic nitrogen to the soil diminishes the production of nitrogenase by plants and microorganisms to sustain their fixation of atmospheric nitrogen, which becomes available for plant nutrition.
Heavy machinery also compacts the soil and degrades its structure, disturbing the balance of water and air in the soil that supports root growth and soil organisms; further, using mineral fertilizers as a substitute for restoration of soil organic matter diminishes the abundance and diversity of soil microorganism populations.

It is true that under a variety of conditions, applications of phosphorus fertilizer and rock phosphate in particular can be beneficial and cost-effective. But from a sustainable agriculture perspective, more attention should be paid to managing the soil biota along with crops so as to get the most benefit from the latter.
Norman T. Uphoff
Professor of Government and International Agriculture
Cornell University

Gregarious Cats
The Taming of the Cat,” by Carlos A. Driscoll, Juliet Clutton-Brock, Andrew C. Kitchener and Stephen J. O’Brien, is largely unsubstantiated and erroneous with regard to the social behavior of domestic cats. Cats do live in groups if the opportunity is available, and each group has a female matriarch and an alpha male. Feral cats always form groups, which are referred to as colonies, and people who care for numerous cats all report this type of hierarchy. As for the cats being of no particular benefit, the authors should consider what species controls the more than 40 eggs laid by many species of snakes, not to mention rodents, whose only other predators are birds of prey and opossums.
“Gary in Tampa”

DRISCOLL REPLIES: A particular sentence seems to have caused confusion, one where we write: “Cats, in contrast, are solitary hunters.” What should have appeared in print is the more specific: “Wildcats, in contrast, are solitary hunters.” The social structure of feral cats is heavily influenced by resource availability. Unless they are feeding from a point source (perhaps a kind person or a garbage dump), feral cats sourcing their own food are solitary. Yet even well-socialized cats do not achieve the level of sociality seen in lions, which hunt cooperatively.

As for their benefits, cats have never been bred for any “behavior” in the sense of a utilitarian task such as shepherding, retrieving, guarding or even pulling, as some domestic dogs were.

It has been suggested that the plagues afflicting Europe during the Middle Ages are a consequence of a reduction in cat numbers during that time and a supposed rise in rat numbers. But humans’ susceptibility at the time had more to do with the Little Ice Age and the Great Famine—with resulting changes in socioeconomic structure, living patterns and hygiene—and also with the prevalence of the black rat, Rattus rattus. The plagues ended after the climate improved, promoting a restoration of agricultural productivity and more dispersed living quarters. Perhaps most important, the black rat was displaced by the brown rat (R. norvegicus), which is not as sus­ceptible to infection. The inability of cats to control plague is anecdotally highlighted by noting that the plague also struck places where cats were always
in high density.

Note: This article was originally printed with the title, "Letters."