Letters

Article excerpt

Pushing Capacity

In his article "Collapse" [4/05], Jared Diamond chooses the population that inhabits the highlands of New Guinea as an example of a society that has solved its environmental problems. Unfortunately, the pioneering work of James B. Watson, an anthropologist at the University of Washington in Seattle, has shown that the favorable picture of New Guinea described by early explorers was not a longestablished one, but rather just a snapshot taken during a period of rapid change.

For much of New Guinea's prehistory, populations in the highlands depended on hunting and gathering, supplemented by agriculture. Around 350 years ago, sweet-potato vines arrived from Indonesia, making it possible for the first time to store surplus food in the form of livestock: pigs. Our studies of precolonial traditions among the Enga in New Guinea show that once they could produce a surplus, change was rapid. On the eve of first contact, according to Enga elders, the population was growing rapidly, its growth was accompanied by runaway competition, demands on land and production were ever accelerating, and warfare was rampant. It is likely that highland societies were headed for collapse.

Polly Wicssncr

University of Utah

Salt Lake City, Utah

AkU Tumu

Enga Cultural Centre

Wabag, Enga Province,

Papua New Guinea

Jared Diamond states that one of the causes of collapse at Copan "was a failure of the Mayan kings and nobles to address problems within their control." But the archaeological evidence indicates to me that the Mayan rulers were well aware of many of the environmental problems they faced in the second half of the eighth century A.D., and that they took a number of steps in response. For example, they undertook massive building and sculptural programs to glorify the gods (and themselves), which displaced farmers into nonfood-producing labor in the cities. That put added stresses on their cities. Where Mr. Diamond sees no action, I see definite actions that in hindsight probably were not the best.

Jeremy A. Sabloff

University of Pennsylvania Museum

Philadelphia, Pennsylvania

Pick of the Crop

The book Mendel in the Kitchen: A Scientist's View of Genetically Modified Foods, reviewed by Laurence A. Marschall ["Bookshelf," 3/05], suggests that if only people understood the science behind genetically modified (GM) food crops, they would embrace the new technology. As a molecular biologist, I understand the science, and I am very much opposed to GM crops in their present form.

Nina Fedoroffand Nancy Marie Brown are incorrect to imply that GM technology is the same as standard plant breeding. Introducing foreign material into plant DNA is neither "predictable" nor "precise." The procedures of cell culture and transformation used in producing GM crops cause many random mutations and chromosomal rearrangements. Mutations that cause subtle but significant changes in plant metabolism need not be lethal to the plant; but consuming such a plant could lead to serious health problems.

If GM technology is as safe as Ms. Fedoroffand Ms. Brown claim it is, why are the biotechnology producers so opposed to mandatory safety testing and labeling?

Pamela Maker

LaJolla, California :

NINA FEDOROFF REPLIES:

In our book Nancy Marie Brown and I address all of the issues Pamela Maher raises. Most gene insertions have little or no effect on the plant, but the cell-culture procedures used in transforming some plants are indeed mutagenic. Cell-culture procedures, chemical mutagens, and radiation all have been applied in what people now refer to as traditional, or conventional, plant breeding for the better part of a century. …